88 results on '"Dennis P. Phillips"'
Search Results
2. Propofol administration during catheter-directed interventions for intermediate-risk pulmonary embolism is associated with major adverse events
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Theodore H. Yuo, Efthymios D. Avgerinos, Patrick Cherfan, Mohamed S. Zaghloul, Rabih A. Chaer, Adham N. Abou Ali, and Dennis P. Phillips
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Adult ,Male ,Time Factors ,Sedation ,medicine.medical_treatment ,Perforation (oil well) ,030204 cardiovascular system & hematology ,Risk Assessment ,03 medical and health sciences ,0302 clinical medicine ,Risk Factors ,medicine ,Humans ,Thrombolytic Therapy ,030212 general & internal medicine ,Adverse effect ,Propofol ,Stroke ,Aged ,Retrospective Studies ,Thrombectomy ,Intracerebral hemorrhage ,business.industry ,Thrombolysis ,Middle Aged ,medicine.disease ,Pulmonary embolism ,Treatment Outcome ,Anesthesia ,Female ,Surgery ,medicine.symptom ,Pulmonary Embolism ,Cardiology and Cardiovascular Medicine ,business ,Anesthetics, Intravenous ,medicine.drug - Abstract
Objective Catheter-directed interventions (CDIs) have been increasingly used for selected patients with acute intermediate-risk (submassive) pulmonary embolism (sPE) to prevent decompensation, mortality, and potentially long-term sequelae. The purpose of the present study was to determine whether the choice of anesthetic during these interventions has an effect on the postprocedural outcomes. Methods Patients who had undergone CDI for acute sPE from 2009 to 2019 were identified and grouped according to the intraprocedural use of propofol. The primary outcome was in-hospital intra- or postprocedural major adverse events, defined as the need for intubation, progression to massive pulmonary embolism, and in-hospital death. Major bleeding events (ie, intracerebral hemorrhage, transfusion of ≥2 U, the need for reintervention) were also assessed. Multivariate logistic regression analysis was used to evaluate the predictors of the studied outcomes. Results During the study period, 340 patients (age, 58.74 ± 15.22 years; 51.2% men) had undergone CDI for sPE (85 standard thrombolysis, 229 ultrasound-assisted thrombolysis, 26 suction thrombectomy). Propofol had been used for 36 patients (10.6%); the remaining 304 patients (89.4%) had received midazolam plus fentanyl, morphine, or hydromorphone for anesthesia. The baseline characteristics of both groups were similar, except for age, hypertension, American Society of Anesthesiologists class, and procedure type, with ultrasound-assisted thrombolysis the predominant procedure for the no-propofol group (74%). Overall, 18 patients had experienced ≥1 events of the composite outcome (ie, 10 intubations, 11 decompensations, 2 surgical conversions, 3 deaths). The propofol group had a significantly greater adverse event rate (13.8%; n = 5) compared with the no-propofol group (4.2%; n = 13; P = .015). On multivariate analysis, propofol was still a predictive factor for adverse events (odds ratio, 3.79; 95% confidence interval, 1.11-12.93; P = .03). A total of 16 patients had experienced major bleeding or other procedure-related events, including stroke in 4 (1.17%), coronary sinus perforation in 1, tricuspid valve rupture in 1, and the need for transfusion in 10 patients. The type of intervention (ie, standard thrombolysis, ultrasound-assisted thrombolysis, suction thrombectomy) was not a predictive factor for any studied outcome. Conclusions CDIs are low-risk procedures with minimal postoperative morbidity and mortality in the setting of acute sPE. However, the use of propofol for intraprocedural sedation should be avoided because it can have detrimental effects.
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- 2021
3. The perioperative application of High Flow Nasal Cannula: a single center experience
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Ezeldeen Abuelkasem, Dennis P. Phillips, Ibtesam A. Hilmi, and Philip C. Carullo
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medicine.medical_specialty ,business.industry ,Sedation ,medicine.medical_treatment ,Perioperative ,Single Center ,medicine.disease_cause ,Patient care ,Intensive care ,Oxygen therapy ,medicine ,medicine.symptom ,business ,High flow ,Intensive care medicine ,Nasal cannula - Abstract
The physiologic benefits of high-flow nasal cannula (HFNC) therapy are well documented in the intensive care literature, yet only a handful of case reports describe its perioperative use. Our single center experience explored comprehensive applications of HFNC in the perioperative setting. Over a ten-month period, HFNC was used in the care of 85 medically complex patients either as an adjuvant or main oxygen therapy during induction of general anesthesia, maintenance of deep intraoperative sedation, and during early postoperative care. Here, we illustrate clinical scenarios in which HFNC therapy made patient care safer and describe a framework for integrating this technology into the anesthesia practice at our institution.
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- 2020
4. Comparison of Anticoagulation Strategies in Patients Requiring Venovenous Extracorporeal Membrane Oxygenation
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Christopher M. Sciortino, John P. Ryan, Dennis P. Phillips, Hernando Gomez, Holt Murray, Pablo G. Sanchez, Rajagopala Padmanabhan, Ryan M. Rivosecchi, Danielle Freeman, Peter Arlia, Aris R.L. Arakelians, and Penny L. Sappington
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Adult ,Male ,medicine.drug_class ,medicine.medical_treatment ,Hemorrhage ,Platelet Transfusion ,Critical Care and Intensive Care Medicine ,Antithrombins ,Plasma ,Extracorporeal Membrane Oxygenation ,medicine ,Extracorporeal membrane oxygenation ,Humans ,Bivalirudin ,Retrospective Studies ,Heparin ,business.industry ,Anticoagulant ,Anticoagulants ,Thrombosis ,Hirudins ,Middle Aged ,medicine.disease ,Peptide Fragments ,Recombinant Proteins ,Platelet transfusion ,Respiratory failure ,Anesthesia ,Female ,Fresh frozen plasma ,Erythrocyte Transfusion ,business ,medicine.drug - Abstract
OBJECTIVES Extracorporeal membrane oxygenation is a life-sustaining therapy for severe respiratory failure. Extracorporeal membrane oxygenation circuits require systemic anticoagulation that creates a delicate balance between circuit-related thrombosis and bleeding-related complications. Although unfractionated heparin is most widely used anticoagulant, alternative agents such as bivalirudin have been used. We sought to compare extracorporeal membrane oxygenation circuit thrombosis and bleeding-related outcomes in respiratory failure patients receiving either unfractionated heparin or bivalirudin for anticoagulation on venovenous extracorporeal membrane oxygenation support. DESIGN Retrospective cohort study. SETTING Single-center, cardiothoracic ICU. PATIENTS Consecutive patients requiring venovenous extracorporeal membrane oxygenation who were maintained on anticoagulation between 2013 and 2020. INTERNVENTIONS IV bivalirudin or IV unfractionated heparin. MEASUREMENTS AND MAIN RESULTS Primary outcomes were the presence of extracorporeal membrane oxygenation in-circuit-related thrombotic complications and volume of blood products administered during extracorporeal membrane oxygenation duration. One hundred sixty-two patients receiving unfractionated heparin were compared with 133 patients receiving bivalirudin for anticoagulation on venovenous extracorporeal membrane oxygenation. In patients receiving bivalirudin, there was an overall decrease in the number of extracorporeal membrane oxygenation circuit thrombotic complications (p < 0.005) and a significant increase in time to circuit thrombosis (p = 0.007). Multivariable Cox regression found that heparin was associated with a significant increase in risk of clots (Exp[B] = 2.31, p = 0.001). Patients who received bivalirudin received significantly less volume of packed RBCs, fresh frozen plasma, and platelet transfusion (p < 0.001 for each). There was a significant decrease in the number major bleeding events in patients receiving bivalirudin, 40.7% versus 11.7%, p < 0.001. CONCLUSIONS Patients receiving bivalirudin for systemic anticoagulation on venovenous extracorporeal membrane oxygenation experienced a decrease in the number of extracorporeal membrane oxygenation circuit-related thrombotic events as well as a significant decrease in volume of blood products administered.
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- 2021
5. The Difficult Airway after Endoscopic Endonasal Skull Base Surgery: A Case Series and Management Algorithm
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Carl H. Snyderman, Dennis P. Phillips, Joseph M. Darby, and Courtney Chou
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Male ,medicine.medical_specialty ,Endoscopic endonasal surgery ,medicine.medical_treatment ,Risk Assessment ,Skull Base Neoplasms ,Cohort Studies ,03 medical and health sciences ,Postoperative Complications ,Sex Factors ,0302 clinical medicine ,030202 anesthesiology ,medicine ,Humans ,Registries ,Airway Management ,Difficult airway ,Aged ,Retrospective Studies ,business.industry ,Age Factors ,Endoscopy ,Middle Aged ,Prognosis ,Management algorithm ,Surgery ,Airway Obstruction ,Skull ,Treatment Outcome ,medicine.anatomical_structure ,Otorhinolaryngology ,Skull base surgery ,Female ,Airway management ,business ,Algorithms ,030217 neurology & neurosurgery - Abstract
To analyze difficult airway situations affecting patients after endoscopic endonasal surgery (EES) for skull base tumors and to develop an airway management algorithm.Case series with chart review.Single tertiary care center.Eleven difficult airway events occurred among patients after EES for skull base tumors, as identified through a retrospective review of our institutional Difficult Airway Management Team registry from January 2008 to March 2016. Data from these events included patient demographics, event characteristics, airway management techniques, and outcomes. Results were used to design a difficult airway protocol.The majority of patients were obese (63.6%) and had a dural defect (90.9%), each of which was repaired with a vascularized flap. The most common reasons for the difficult airway call were concern for using mask ventilation in a patient with a dural defect (27.3%) and difficult airway anatomy (27.3%). Two patients did not require airway intervention; 8 were intubated; and 1 underwent cricothyroidotomy. Videolaryngoscopy was the most common first-attempt intubation technique, followed by conventional direct laryngoscopy. Effective adjunctive techniques included intubation through a laryngeal mask airway and bougie-guided intubation. As compared with simple mask ventilation, laryngeal mask airway-assisted ventilation was associated with a decreased incidence of postevent cerebrospinal fluid leak. There were no incidences of postevent pneumocephalus, cardiopulmonary arrest, or mortality.We propose a difficult airway algorithm for patients following EES of the skull base, with sequential recommendations for airway management methods and commentary on adjunctive techniques.
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- 2018
6. Severe Dizziness and Syncope After HeartMate 3 Implantation Requiring Pump Exchange
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Gavin Hickey, Robert L. Kormos, Hiroshi Kagawa, Dennis P. Phillips, Arman Kilic, Garrett N. Coyan, Christopher M. Sciortino, Michael A. Mathier, and Katherine J Davis
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Cardiomyopathy, Dilated ,Male ,Reoperation ,Pulmonary and Respiratory Medicine ,medicine.medical_specialty ,Computed Tomography Angiography ,medicine.medical_treatment ,Cardiac Output, Low ,Cardiomyopathy ,030204 cardiovascular system & hematology ,Dizziness ,Severity of Illness Index ,Syncope ,Prosthesis Implantation ,Ventricular Dysfunction, Left ,03 medical and health sciences ,Imaging, Three-Dimensional ,Postoperative Complications ,0302 clinical medicine ,Internal medicine ,Severity of illness ,medicine ,Humans ,Device Removal ,Computed tomography angiography ,Framingham Risk Score ,biology ,medicine.diagnostic_test ,business.industry ,Syncope (genus) ,Middle Aged ,medicine.disease ,biology.organism_classification ,Clinical trial ,Treatment Outcome ,030228 respiratory system ,Echocardiography ,Ventricular assist device ,Cardiology ,Equipment Failure ,Surgery ,Heart-Assist Devices ,Cardiology and Cardiovascular Medicine ,Complication ,business ,Follow-Up Studies - Abstract
Implantation of the HeartMate 3 (HM3) left ventricular assist device (Abbott Laboratories, Lake Bluff, IL) continues to increase as the results of European and U.S. clinical trials become available. Although the large trials adequately capture the more common and expected outcomes, rare and unexpected clinical complications will continue to appear with higher volumes of implantation. This report describes a rare complication of severe refractory postural dizziness and syncope after successful implantation of an HM3 in a patient who ultimately required pump exchange to a HeartWare HVAD (HeartWare, Framingham, MA) for resolution of symptoms.
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- 2019
7. Paradoxical Tumor Embolism and Recurrent Intracardiac Mass From Uterine Intravenous Leiomyomatosis
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Joshua Knight, Herbert J. Zeh, Kathirvel Subramaniam, Vinay Badhwar, Stephen A. Esper, and Dennis P. Phillips
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Adult ,medicine.medical_specialty ,Vena Cava, Inferior ,030204 cardiovascular system & hematology ,Inferior vena cava ,Intracardiac injection ,law.invention ,Heart Neoplasms ,03 medical and health sciences ,0302 clinical medicine ,Leiomyomatosis ,law ,Cardiopulmonary bypass ,medicine ,Humans ,Heart Atria ,business.industry ,Tumor Embolism ,Neoplastic Cells, Circulating ,medicine.disease ,Intravenous leiomyomatosis ,Surgery ,Anesthesiology and Pain Medicine ,030228 respiratory system ,medicine.vein ,Uterine Neoplasms ,Patent foramen ovale ,Female ,Neoplasm Recurrence, Local ,Cardiology and Cardiovascular Medicine ,business - Published
- 2017
8. Perioperative Echocardiographic Diagnosis of Regional Wall Motion Abnormalities: Not All of Them are Ischemic!
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Dennis P. Phillips, Michael L. Boisen, Mathew W Caldwell, Stephen M. McHugh, Kathirvel Subramaniam, A Murat Kaynar, Li Meng, and Robert H Boretsky
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03 medical and health sciences ,medicine.medical_specialty ,0302 clinical medicine ,business.industry ,Internal medicine ,Cardiology ,Medicine ,030212 general & internal medicine ,Wall motion ,Perioperative ,Radiology ,030204 cardiovascular system & hematology ,business - Abstract
We present three noncardiac surgical patients with regional left ventricular dysfunction diagnosed by bedside echocardiography: One intraoperative, another immediate postoperative, and a third one with preoperative hemodynamic instability. We review the differential diagnosis and the growing role of perioperative transthoracic echocardiography. How to cite this article Boisen ML, McHugh SM, Boretsky RH, Phillips DP, Meng L, Caldwell MW, Kaynar AM, Subramaniam K. Perioperative Echocardiographic Diagnosis of Regional Wall Motion Abnormalities: Not All of Them are Ischemic! J Perioper Echocardiogr 2016;4(2):70-73.
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- 2016
9. The Difficult Airway (DRAFT)
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Joshua Knight and Dennis P. Phillips
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medicine.medical_specialty ,business.industry ,medicine ,respiratory system ,Intensive care medicine ,business ,Difficult airway ,respiratory tract diseases - Abstract
The difficult airway invariably presents itself to all airway managers and is mostly unpredictable in the context of rapid response team (RRT) calls. A multiprofessional difficult airway team (DAT) that could be called for airway emergencies is likely to reduce complications and death. The DAT is organized with predefined roles for each member so that rapid intervention occurs during the emergency. Priority is given to oxygenation throughout the airway response. The anticipated and unanticipated difficult airways should be approached differently and often require medication adjuncts that should be carefully chosen. Airway devices such as the video laryngoscope and the laryngeal mask airway (LMA) have dramatically improved the ability to secure an airway quickly. Finally, it is important to recognize when a surgical airway is needed in the setting of the RRT calls.
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- 2018
10. Cystic Fibrosis and Lower-Extremity Edema: A Case of Intraoperative Diagnosis of Acute Deep Venous Thrombosis and Pulmonary Embolism in a Double-Lung Transplant Recipient Using Point-of-Care Ultrasound
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Travis Schisler, Kathirvel Subramaniam, Dennis P. Phillips, and Vladyslav Melnyk
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Male ,medicine.medical_specialty ,Double lung transplant ,Cystic Fibrosis ,medicine.medical_treatment ,Cystic fibrosis ,Intraoperative Period ,medicine ,Lung transplantation ,Edema ,Humans ,Lower extremity edema ,Venous Thrombosis ,Acute deep venous thrombosis ,business.industry ,Point of care ultrasound ,Middle Aged ,medicine.disease ,Transplant Recipients ,Pulmonary embolism ,Anesthesiology and Pain Medicine ,Lower Extremity ,Point-of-Care Testing ,Acute Disease ,Radiology ,Cardiology and Cardiovascular Medicine ,business ,Pulmonary Embolism ,Echocardiography, Transesophageal ,Lung Transplantation - Published
- 2017
11. Selective adaptation in sound lateralization is not due to a repulsion effect
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Emma J Mew, Dennis P. Phillips, and Susan E. Hall
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Tone (musical instrument) ,Acoustics and Ultrasonics ,Arts and Humanities (miscellaneous) ,Dichotic listening ,Acoustics ,Perception ,media_common.quotation_subject ,Adaptation (eye) ,Psychology ,Neuroscience ,Lateralization of brain function ,media_common - Abstract
Selective adaptation studies in dichotic sound lateralization have contributed to a three-channel model of lateralization mechanisms. They usually have employed highly-lateralized adaptor stimuli, and the expression of the selective adaptation is the perceptual shift of test tone locations away from that of the adaptor. The present study employed modestly lateralized adaptors so that any repulsion mechanism could be visualized in distorted position judgments for test tones on both sides of the adaptor stimuli. Comparison of position reports for tones lateralized using interaural time differences before and after selective adaptation provided no evidence for a repulsion effect.
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- 2014
12. Acoustic Stapedius Reflex Function in Man Revisited
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Steven J. Aiken, Jessica N. Andrus, Dennis P. Phillips, and Manohar Bance
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Adult ,Male ,medicine.medical_specialty ,Stapes Surgery ,Audiology ,Stimulus (physiology) ,Tendons ,Background noise ,Young Adult ,Speech and Hearing ,Signal-to-noise ratio ,otorhinolaryngologic diseases ,medicine ,Humans ,Acoustic reflex ,medicine.diagnostic_test ,business.industry ,Auditory Threshold ,Stapedius ,Middle Aged ,Reflex, Acoustic ,Noise masking ,Otorhinolaryngology ,Case-Control Studies ,QUIET ,Speech Perception ,Reflex ,Audiometry, Pure-Tone ,Female ,Audiometry ,Noise ,business ,Perceptual Masking - Abstract
Objective: The objective of this study was to examine the role of the acoustic stapedius reflex in the protection of speech recognition from the upward spread of masking arising from low-frequency background noise. Design: Speech recognition scores were measured for nine control participants (19–34 years) and six patients with transected stapedius tendons poststapedotomy (39–57 years) as a function of the amplitude of a low-frequency masker, presented at nominal signal to noise ratios of +5 dB, –5 dB, and –15 dB. All participants had pure-tone hearing thresholds in the normal range. Continuous high-pass noise was present in all conditions to avoid ceiling effects; this reduced performance in quiet to approximately 85% for all participants. Scores were measured for soft and loud nonsense syllables (average third octave band levels of 35 and 65 dB SPL), so that a comparison of the low-frequency noise masking functions at the two levels would provide information about the effects of the reflex on speech intelligibility in noise. A third group of nine control participants (19–22 years) listened in the presence of a low-frequency masker gated to come on 1 sec before stimulus onset, to reduce the likelihood of reflex adaptation. The Speech-Intelligibility Index was used to quantify the amount of speech information available in each condition. Results: Patients with transected tendons performed more poorly than control participants as a function of Speech-Intelligibility Index in all conditions, even at levels that were too soft for reflex activation. This could be because of postsurgical differences in sensitivity, the more advanced age of poststapedotomy group, or differences in medial olivocochlear inhibition. For loud speech, patient performance fell nearly linearly with increases in the low-frequency masker, but control participants’ performance declined little as the signal to noise ratio declined from +5 to –5 dB, and then fell rapidly as the ratio declined to –15 dB. This plateau in the masking function did not occur for the patients. Masking functions obtained with the gated low-frequency masker were either highly similar or poorer to those obtained with a continuous masker, suggesting that the use of a continuous low frequency masker did not result in significant reflex adaptation. Conclusions: The stapedius reflex appears to offer some protection from the upward spread of masking of speech by background low-frequency noise at moderate levels, but not at high levels. (Ear & Hearing 2013:34;e38–e51)
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- 2013
13. The three-channel model of sound localization mechanisms: Interaural time differences
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Susan E. Hall, Rachel N. Dingle, and Dennis P. Phillips
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Adult ,Sound localization ,Analysis of Variance ,Time Factors ,Acoustics and Ultrasonics ,Computer science ,Acoustics ,Auditory Threshold ,Ear ,Adaptation (eye) ,Interaural time difference ,Middle Aged ,Neurophysiology ,Azimuth ,Young Adult ,Acoustic Stimulation ,Arts and Humanities (miscellaneous) ,Frequency domain ,Adaptation, Psychological ,Humans ,Sound Localization ,Psychoacoustics ,Communication channel - Abstract
Previous psychophysical work on sound localization in humans has proposed that a midline channel be added to the current two-channel model of mammalian sound localization mechanisms. Evidence for this third channel has been found in interaural time difference (ITD) studies with low-frequency tones, and interaural level difference (ILD) studies with both high- and low-frequency tones. The latter is interesting because it suggests that, despite the fact that low frequencies do not generate significant ILDs for humans in natural settings, there is a constancy of ILD coding mechanisms across the frequency domain. To complement this finding, the present study sought to determine whether the three-channel model holds for ITDs at high frequencies. In three experiments, a selective adaptation paradigm was used in combination with transposed tones to probe for the existence of three (left, right, and midline) perceptual channels for sound source azimuth. The experiments provided evidence for lateral hemifield ITD channels but little evidence for a midline ITD channel at high frequencies.
- Published
- 2013
14. Dual mechanisms in the perceptual processing of click train temporal regularity
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Moragh Jang, Dennis P. Phillips, Susan E. Hall, and Rachel N. Dingle
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Adult ,Male ,Acoustics and Ultrasonics ,Acoustics ,media_common.quotation_subject ,Speech recognition ,Auditory Threshold ,Middle Aged ,Young Adult ,Noise ,Acoustic Stimulation ,Arts and Humanities (miscellaneous) ,Perception ,Speech Perception ,Humans ,Female ,ComputerSystemsOrganization_SPECIAL-PURPOSEANDAPPLICATION-BASEDSYSTEMS ,Wideband ,Pitch Perception ,Sensitivity (electronics) ,Jitter ,media_common ,Mathematics - Abstract
Two experiments measured human sensitivity to temporal jitter in 25-click trains with inter-click intervals (ICIs) between 5 and 100 ms. In a naturalistic experiment using wideband clicks, jitter thresholds were a nonmonotonic function of ICI, peaking for ICIs near 40-60 ms. In a subsequent experiment, clicks were high-passed and presented against a low-frequency noise masker. Jitter threshold vs ICI functions lost the positive slope over short ICIs but retained the negative slope at long ICIs. The same behavior was seen in click rate discrimination tasks. Different processes mediate regularity analysis for click trains with ICIs above and below 40-60 ms.
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- 2012
15. The three-channel model of sound localization mechanisms: Interaural level differences
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Rachel N, Dingle, Susan E, Hall, and Dennis P, Phillips
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Adult ,Analysis of Variance ,Judgment ,Sound Spectrography ,Acoustic Stimulation ,Acoustics and Ultrasonics ,Arts and Humanities (miscellaneous) ,Humans ,Sound Localization ,Middle Aged ,Pitch Perception ,Models, Biological - Abstract
The current understanding of mammalian sound localization is that azimuthal (horizontal) position assignments are dependent upon the relative activation of two populations of broadly-tuned hemifield neurons with overlapping medial borders. Recent psychophysical work has provided evidence for a third channel of low-frequency interaural time difference (ITD)-sensitive neurons tuned to the azimuthal midline. However, the neurophysiological data on free-field azimuth receptive fields, especially of cortical neurons, has primarily studied high-frequency cells whose receptive fields are more likely to have been shaped by interaural level differences (ILDs) than ITDs. In four experiments, a selective adaptation paradigm was used to probe for the existence of a midline channel in the domain of ILDs. If no midline channel exists, symmetrical adaptation of the lateral channels should not result in a shift in the perceived intracranial location of subsequent test tones away from the adaptors because the relative activation of the two channels will remain unchanged. Instead, results indicate a shift in perceived test tone location away from the adaptors, which supports the existence of a midline channel in the domain of ILDs. Interestingly, this shift occurs not only at high frequencies, traditionally associated with ILDs in natural settings, but at low frequencies as well.
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- 2012
16. Stability of central binaural sound localization mechanisms in mammals, and the Heffner hypothesis
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Dennis P. Phillips, Rachel N. Dingle, and Chelsea K. Quinlan
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Mammals ,Sound localization ,Communication ,business.industry ,Mechanism (biology) ,Cognitive Neuroscience ,Auditory Threshold ,Evolutionary pressure ,Biology ,Neurophysiology ,Stability (probability) ,Functional Laterality ,Behavioral Neuroscience ,Neuropsychology and Physiological Psychology ,Acoustic Stimulation ,Animals ,Humans ,Sound Localization ,Psychological Theory ,business ,Neural coding ,Neuroscience ,Binaural recording ,Coding (social sciences) - Abstract
Heffner (2004) provided an overview of data on the evolutionary pressures on sound localization acuity in mammals. Her most important finding was that sound localization acuity was most strongly correlated with width of field of best vision. This correlation leaves unexplained the mechanism through which evolutionary pressures affect localization acuity in different mammals. A review of the neurophysiology of binaural sound localization cue coding, and the behavioural performance it supports, led us to two hypotheses. First, there is little or no evidence that the neural mechanisms for coding binaural sound location cues, or the dynamic range of the code, vary across mammals. Rather, the neural coding mechanism is remarkably constant both across species, and within species across frequency. Second, there is no need to postulate that evolutionary pressures are exerted on the cue coding mechanism itself. We hypothesize instead that the evolutionary pressure may be on the organism's ability to exploit a ‘lower envelope principle’ (after Barlow, 1972 ).
- Published
- 2012
17. Synchronous auditory nerve activity in the carboplatin-chinchilla model of auditory neuropathy
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Yuqing Guo, Rachel N. Dingle, R. Burkard, Dennis P. Phillips, and C. D. Cowper-Smith
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Chinchilla ,Inferior colliculus ,Auditory Pathways ,Time Factors ,Acoustics and Ultrasonics ,Auditory neuropathy ,Carboplatin ,Arts and Humanities (miscellaneous) ,biology.animal ,Evoked Potentials, Auditory, Brain Stem ,Reaction Time ,otorhinolaryngologic diseases ,Animals ,Humans ,Medicine ,Cochlear Nerve ,Auditory Diseases, Central ,Inferior Colliculi ,biology ,business.industry ,Cochlear nerve ,Neurophysiology ,medicine.disease ,Jasa Express Letters ,Disease Models, Animal ,Auditory brainstem response ,medicine.anatomical_structure ,Hair cell ,business ,Neuroscience - Abstract
Two hallmark features of auditory neuropathy (AN) are normal outer hair cell function in the presence of an absent∕abnormal auditory brainstem response (ABR). Studies of human AN patients are unable to determine whether disruption of the ABR is the result of a reduction of neural input, a loss of auditory nerve fiber (ANF) synchrony, or both. Neurophysiological data from the carboplatin model of AN reveal intact neural synchrony in the auditory nerve and inferior colliculus, despite significant reductions in neural input. These data suggest that (1), intact neural synchrony is available to support an ABR following carboplatin treatment and, (2), impaired spike timing intrinsic to neurons is required for the disruption of the ABR observed in human AN.
- Published
- 2010
18. Auditory Temporal Gap Detection in Children with and without Auditory Processing Disorder
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Jessica N. Andrus, Dennis P. Phillips, and Michel Comeau
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Male ,Auditory perception ,Research design ,medicine.medical_specialty ,Loudness Perception ,media_common.quotation_subject ,Audiology ,Speech and Hearing ,Perception ,medicine ,Humans ,Attention ,Child ,Pitch Perception ,media_common ,Hearing Tests ,Auditory Perceptual Disorders ,Auditory Threshold ,Time perception ,Gap detection ,Auditory processing disorder ,medicine.disease ,Acoustic Stimulation ,Time Perception ,Auditory Perception ,Auditory imagery ,Female ,Silent period ,Psychology - Abstract
Background: Auditory gap detection is a measure of temporal acuity. The paradigm comes in two forms, distinguished by whether the sounds bounding the silent period are the same (within channel [WC]) or different (between channel [BC]). Purpose: The purpose of this study was to test normal children and children referred for auditory processing disorder (APD) assessment, with both gap detection paradigms. Research Design: Best gap durations (i.e., shortest reliably detected gaps) were measured in a two-interval, two-alternative forced-choice design embedded within a modified method of limits, for both WC and BC paradigms, with stimuli presented at 55 dB HL. Study Sample: Sixteen control children and 20 children referred for APD assessment participated in the study. Of the 20 referred children, 9 were diagnostically positive for APD (APD+), and 11 were negative (APD−). The mean age of children in all three groups was 10–11 yr. Data Collection and Analysis: Data collected were best gap durations for each paradigm, for each child. Group differences were assessed using Kruskal-Wallis analyses of variance. Results: WC best gap durations were very similar across the three participant groups. BC best gap durations varied significantly between listener groups, with the greatest difference being between controls and APD+ samples. Conclusions: BC best gap durations differed among the listener groups while WC ones did not. This suggests that the relative timing perceptual operations required by the BC task are more susceptible to the perceptual disturbances in APD than is the simple event detection required by the WC task.
- Published
- 2010
19. Effect of stimulus hemifield on free-field auditory saltation
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Dennis P. Phillips and Yoko Ishigami
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Male ,medicine.medical_specialty ,Auditory Pathways ,Time Factors ,Speech recognition ,media_common.quotation_subject ,Illusion ,Stimulus (physiology) ,Audiology ,Illusions ,Sensory Systems ,Acoustic Stimulation ,Perception ,medicine ,Humans ,Female ,Sound Localization ,Psychology ,Perceptual Masking ,media_common - Abstract
Auditory saltation is the orderly misperception of the spatial location of repetitive click stimuli emitted from two successive locations when the inter-click intervals (ICIs) are sufficiently short. The clicks are perceived as originating not only from the actual source locations, but also from locations between them. In two tasks, the present experiment compared free-field auditory saltation for 90 degrees excursions centered in the frontal, rear, left and right acoustic hemifields, by measuring the ICI at which subjects report 50% illusion strength (subjective task) and the ICI at which subjects could not distinguish real motion from saltation (objective task). A comparison of the saltation illusion for excursions spanning the midline (i.e. for frontal or rear hemifields) with that for stimuli in the lateral hemifields (left or right) revealed that the illusion was weaker for the midline-straddling conditions (i.e. the illusion was restricted to shorter ICIs). This may reflect the contribution of two perceptual channels to the task in the midline conditions (as opposed to one in the lateral hemifield conditions), or the fact that the temporal dynamics of localization differ between the midline and lateral hemifield conditions. A subsidiary comparison of saltation supported in the left and right auditory hemifields, and therefore by the right and left auditory forebrains, revealed no difference.
- Published
- 2008
20. A perceptual architecture for sound lateralization in man
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Dennis P. Phillips
- Subjects
Sound localization ,Auditory Pathways ,media_common.quotation_subject ,Speech recognition ,Models, Neurological ,Population ,Stimulus (physiology) ,Lateralization of brain function ,Perceptual-based 3D sound localization ,Perception ,Psychophysics ,Animals ,Humans ,Sound Localization ,Pitch Perception ,education ,Cochlear Nerve ,media_common ,Auditory Cortex ,education.field_of_study ,Neurophysiology ,Strigiformes ,Adaptation, Physiological ,Sensory Systems ,Acoustic Stimulation ,Evoked Potentials, Auditory ,Cues ,Psychology ,Neuroscience ,Psychoacoustics - Abstract
There are two general neurophysiological models of sound lateralization mechanisms which may be active in man. Both of the models are derived from studies in animals (one in barn owls, and one in mammals), and both have displayed some weakness in generalizability. One model advocates a population of neurons narrowly tuned to different interaural disparity values across the behaviorally relevant range, so that the cue value, and therefore the source azimuth, is represented by which neurons of the array are activated by the stimulus. The second model posits the existence of only two neural channels, each broadly tuned to interaural cue values favoring one acoustic hemifield, so that, especially for sources near the midline, cue value and therefore source azimuth is encoded by the relative activation of the two neural populations. The present article reviews three recent psychophysical studies, each using selective adaptation paradigms to probe sound lateralization mechanisms based on interaural disparities in normal human listeners. These experiments provided evidence on the frequency-specificity of interaural disparity coding and revealed its sensitivity to recent stimulus history. The data from those studies, however, also help distinguish the two lateralization models, and favor a perceptual architecture for sound lateralization in man based on the activity of two, hemifield-tuned azimuthal channels.
- Published
- 2008
21. The effects of lateralized adaptors on lateral position judgements of tones within and across frequency channels
- Author
-
Susan E. Hall, Dennis P. Phillips, and Bronwyn K. Vigneault-MacLean
- Subjects
Adult ,Male ,Adolescent ,Auditory lateralization ,Acoustics ,Interaural time difference ,Adaptation (eye) ,Models, Psychological ,Adaptation, Physiological ,Lateral position ,Sensory Systems ,Pitch Discrimination ,Tone (musical instrument) ,Acoustic Stimulation ,Laterality ,Psychophysics ,Humans ,Female ,Sound Localization ,Psychology ,psychological phenomena and processes ,Psychoacoustics ,Sign (mathematics) - Abstract
Two experiments examined the effect of highly lateralized adaptor tone pulses on the perceived intracranial location of subsequent test tones. In Experiment 1, adaptor tones of each of two frequencies, highly lateralized to opposite sides by a quarter-period interaural time difference (ITD), were found to shift the perceived intracranial location of test tones of each adaptor frequency away from the side of the adaptor. The shift in perceived location was seen for all test tone ITDs with the same sign as the adaptor tone, and sometimes extended to include test tones with small ITDs favoring the opposite ear. The generality of the effect across test tone ITDs of the same sign as the adaptor suggests that the human auditory lateralization system is built of two (left, right) hemifield-tuned azimuthal channels, and that perceived lateral location depends on the relative outputs of those two channels. In Experiment 2, the perceived location of test tones lateralized by ITD was studied in the same listeners at each of the same two frequencies, but after selective adaptation with tone pulses of only one frequency and laterality. The perceived lateral position of test tones with the same frequency as that of the adaptor underwent the same changes as seen in Experiment 1. The perceived lateral position of test tones of the nonadapted frequency usually shifted weakly in the opposite direction, i.e., in the direction expected if the second adaptor from Experiment 1 had actually been present. These data have implications both for the processes mediating selective adaptation using contingent stimuli, and for the azimuthal tuning of auditory spatial channels in man.
- Published
- 2007
22. The relation between auditory temporal interval processing and sequential stream segregation examined with stimulus laterality differences
- Author
-
Dennis P. Phillips and Susan E. Boehnke
- Subjects
Male ,medicine.medical_specialty ,Dichotic listening ,media_common.quotation_subject ,Interval temporal logic ,Experimental and Cognitive Psychology ,Cognition ,Gap detection ,Time perception ,Stimulus (physiology) ,Audiology ,Sensory Systems ,Developmental psychology ,body regions ,Discrimination, Psychological ,Perception ,Time Perception ,Laterality ,Auditory Perception ,medicine ,Humans ,Female ,Psychology ,General Psychology ,media_common - Abstract
In this study, we examine the effects of laterality differences between noise bursts on two objective measures of temporal interval processing (gap detection and temporal asymmetry detection) and one subjective measure of temporal organization (stream segregation). Noise bursts were lateralized by presentation to different ears or dichotic presentation with oppositely signed interaural level (ILD) or time (ITD) differences. Objective thresholds were strongly affected by ear-of-entry differences, were moderately affected by ILD differences, but were unaffected by ITD differences. Subjectively, A and B streams segregated well on the basis of ear-of-entry or ILD differences but segregated poorly on the basis of ITD differences. These results suggest that perceptual segregation may be driven more effectively by differential activation of the two ears (peripheral channeling) than by differences in perceived laterality.
- Published
- 2005
23. Auditory Saltation in the Vertical Midsagittal Plane
- Author
-
Susan E. Boehnke and Dennis P. Phillips
- Subjects
Male ,media_common.quotation_subject ,Acoustics ,Illusion ,Experimental and Cognitive Psychology ,Monaural ,050105 experimental psychology ,03 medical and health sciences ,0302 clinical medicine ,Illusory motion ,Artificial Intelligence ,Perception ,Psychophysics ,medicine ,Humans ,0501 psychology and cognitive sciences ,Sound Localization ,media_common ,05 social sciences ,Auditory Threshold ,Illusions ,Sensory Systems ,Sagittal plane ,Ophthalmology ,medicine.anatomical_structure ,Acoustic Stimulation ,Auditory Perception ,Female ,Percept ,Psychology ,Auditory illusion ,030217 neurology & neurosurgery - Abstract
Auditory saltation is an illusion in which a train of clicks, the first half of which is presented at one location and the other half of which is presented from a second location, is perceived as originating not only from the anchor points, but also from locations between them. That is, intermediate members of the series of clicks have their spatial locations systematically misperceived. In the present study, auditory saltation was examined for the first time in the vertical midsagittal plane. Subjects rated the perceived continuity of motion for 8-click trains systematically varied in inter-click interval (ICI), direction of motion (up, down), and trial type (‘saltation’ versus ‘real’ motion). In all listeners, saltation stimuli supported robust saltation, but only for trials with ICIs less than about 120 ms. Real motion was rated as continuous for all ICIs. These data indicate that the auditory-saltation illusion can exploit monaural stimulus cues for source location in the generation of the illusory motion percept.
- Published
- 2005
24. Acoustic Hemifields in the Spatial Release from Masking of Speech by Noise
- Author
-
Susan E. Hall, Susan E. Boehnke, Dennis P. Phillips, and Vigneault-MacLean Bk
- Subjects
Adult ,Male ,Analysis of Variance ,medicine.medical_specialty ,Speech Reception Threshold Test ,Angular distance ,media_common.quotation_subject ,Speech recognition ,Speech Intelligibility ,Stimulus (physiology) ,Audiology ,Azimuth ,Speech and Hearing ,Hearing ,Perception ,medicine ,Humans ,Female ,Psychoacoustics ,Noise ,Perceptual Masking ,Mathematics ,media_common - Abstract
The Hearing-in-Noise Test (HINT) is able to measure the benefit to speech intelligibility in noise conferred when the noise masker is displaced 90 degrees in eccentricity from a speech source located at zero degrees azimuth. Both psychoacoustic and neurophysiological data suggest that the perceptual benefit of the 90-degree azimuth separation would be greatest if the speech and noise were presented in different acoustic hemifields, and would be smallest if the two sources were in the same acoustic hemifield. The present study tested this hypothesis directly in ten normal-hearing adult listeners. Using the HINT stimuli, we confirmed the hypothesis. Release from masking scores averaged 8.61 dB for "between-hemifield" conditions, 6.05 dB for HINT conditions, and 1.27 dB for "within-hemifield" conditions, even though all stimulus configurations retained a 90-degree angular separation of speech and noise. These data indicate that absolute separation of speech and noise alone is insufficient to guarantee a significant release from masking, and they suggest that what matters is the location of the stimulus elements relative to the left and right spatial perceptual channels. La Prueba de Audición en Ruido (HINT) permite medir los beneficios para la inteligibilidad del lenguaje en ruido que ocurre cuando el enmascarador de ruido es desplazado 90 grados de la fuente de lenguaje localizada a 0 grados azimut. Tanto los datos psicoacústicos como neurofisiológicos sugieren que el beneficio perceptual de la separación de 90 grados azimut sería mayor si el lenguaje y el ruido fueran presentados en diferentes hemicampos acústicos, y sería menor si las dos fuentes estuvieran en el mismo hemicampo. El presente estudio evaluó esta hipótesis directamente en diez sujetos adultos normo-oyentes. Utilizando los estímulos del HINT, confirmamos la hipótesis. Los puntajes de liberación del enmascaramiento promediaron 8.61 dB para las condiciones de "entre-hemicampos". 6.05 dB para las condiciones del HINT, y 1.27 para las condiciones "dentro del hemicampo", a pesar de que la configuración de todos los estímulos retuvo una separación angular de 90 grados entre el lenguaje y el ruido. Estos datos indican que la separación absoluta del ruido y lenguaje solos es insuficiente para garantizar una liberación significativa del enmascaramiento, y sugieren que lo que importa es la localización de los elementos del estímulo con relación a los canales perceptuales espaciales derecho e izquierdo.
- Published
- 2003
25. Auditory temporal gap detection for noise markers with partially overlapping and non-overlapping spectra
- Author
-
Dennis P. Phillips and Susan E. Hall
- Subjects
Adult ,Male ,Detection threshold ,Acoustics ,Bandwidth (signal processing) ,Auditory Threshold ,Gap detection ,Sensory Systems ,Spectral line ,Computer Science::Sound ,Bounding overwatch ,Time Perception ,Auditory Perception ,Humans ,Female ,Wideband ,Adaptive tracking ,Noise ,Perceptual Masking ,Mathematics - Abstract
Temporal gap detection thresholds were obtained from six listeners using an adaptive tracking method and constant spectrum-level noises. In separate blocks of trials, the markers bounding the gap were systematically varied in their spectral overlap or separation (expressed in equivalent rectangular bandwidths, ERBs). In the same listeners, gap thresholds were also obtained for noises of the same bandwidths as those constituting the overlap in the overlap conditions (in the presence of a wideband notched noise masker: 'mask' conditions). For the spectral overlap/separation conditions, gap thresholds were a systematic, linear function of spectral dissimilarity in four of six listeners. In the mask conditions, gap thresholds were inversely related to bandwidth in all listeners. For the three-, four- and five-ERB conditions, gap thresholds in the same listeners for the spectral overlap conditions were higher than those for mask stimuli with the same available within-channel bandwidth and spectrum levels. These data suggest that the spectral dissimilarity between the markers over-rode the availability of within-channel information in the recovery of the temporal gap.
- Published
- 2002
26. Spatial Stimulus Cue Information Supplying Auditory Saltation
- Author
-
Leanna E D Rutherford, Dennis P. Phillips, Susan E. Boehnke, and Susan E. Hall
- Subjects
Adult ,Male ,Sound localization ,medicine.medical_specialty ,Acoustics ,Experimental and Cognitive Psychology ,Interaural time difference ,Audiology ,Monaural ,050105 experimental psychology ,03 medical and health sciences ,0302 clinical medicine ,Illusory motion ,Artificial Intelligence ,Psychophysics ,medicine ,Humans ,0501 psychology and cognitive sciences ,Sound Localization ,Dichotic listening ,05 social sciences ,Illusions ,Sensory Systems ,Ophthalmology ,Female ,Cues ,Psychology ,Binaural recording ,Auditory illusion ,030217 neurology & neurosurgery - Abstract
Auditory saltation is a misperception of the spatial location of repetitive, transient stimuli. It arises when clicks at one location are followed in perfect temporal cadence by identical clicks at a second location. This report describes two psychophysical experiments designed to examine the sensitivity of auditory saltation to different stimulus cues for auditory spatial perception. Experiment 1 was a dichotic study in which six different six-click train stimuli were used to generate the saltation effect. Clicks lateralised by using interaural time differences and clicks lateralised by using interaural level differences produced equivalent saltation effects, confirming an earlier finding. Switching the stimulus cue from an interaural time difference to an interaural level difference (or the reverse) in mid train was inconsequential to the saltation illusion. Experiment 2 was a free-field study in which subjects rated the illusory motion generated by clicks emitted from two sound sources symmetrically disposed around the interaural axis, ie on the same cone of confusion in the auditory hemifield opposite one ear. Stimuli in such positions produce spatial location judgments that are based more heavily on monaural spectral information than on binaural computations. The free-field stimuli produced robust saltation. The data from both experiments are consistent with the view that auditory saltation can emerge from spatial processing, irrespective of the stimulus cue information used to determine click laterality or location.
- Published
- 2002
27. Central auditory onset responses, and temporal asymmetries in auditory perception
- Author
-
Susan E. Boehnke, Susan E. Hall, and Dennis P. Phillips
- Subjects
Auditory Cortex ,Auditory perception ,medicine.medical_specialty ,Auditory Pathways ,Time Factors ,media_common.quotation_subject ,Auditory Threshold ,Stimulation ,Stimulus (physiology) ,Audiology ,Neurophysiology ,Adaptation, Physiological ,Sensory Systems ,Acoustic Stimulation ,Perception ,Laterality ,Auditory Perception ,medicine ,Psychophysics ,Animals ,Humans ,Second-order stimulus ,Psychology ,media_common - Abstract
Historically, central auditory responses have been studied for their sensitivity to various parameters of tone and noise burst stimulation, with response rate plotted as a function of the stimulus variable. The responses themselves are often quite brief, and locked in time to stimulus onset. In the stimulus amplitude domain, it has recently become clear that these responses are actually driven by properties of the stimulus' onset transient, and this has had important implications for how we interpret responses to manipulations of tone (or noise) burst plateau level. That finding was important in its own right, but a more general scrutiny of the available neurophysiological and psychophysical evidence reveals that there is a significant asymmetry in the neurophysiological and perceptual processing of stimulus onsets and offsets: sound onsets have a more elaborate neurophysiological representation, and receive a greater perceptual weighting. Hypotheses about origins of the asymmetries, derived independently from psychophysics and from neurophysiology, have in common a response threshold mechanism which adaptively tracks the ongoing level of stimulation.
- Published
- 2002
28. Central Auditory System and Central Auditory Processing Disorders: Some Conceptual Issues
- Author
-
Dennis P. Phillips
- Subjects
Speech and Hearing ,medicine.medical_specialty ,Auditory scene analysis ,medicine.anatomical_structure ,Neuroplasticity ,medicine ,Auditory system ,Central auditory processing ,Auditory imagery ,Audiology ,Psychology - Published
- 2002
29. Spatial and temporal factors in auditory saltation
- Author
-
S. E. Hall and Dennis P. Phillips
- Subjects
Adult ,Male ,Auditory perception ,medicine.medical_specialty ,Acoustics and Ultrasonics ,media_common.quotation_subject ,Acoustics ,Illusion ,Interaural time difference ,Audiology ,Stimulus (physiology) ,Monaural ,Functional Laterality ,Arts and Humanities (miscellaneous) ,medicine ,Humans ,media_common ,Mathematics ,Dichotic listening ,Illusions ,Acoustic Stimulation ,Space Perception ,QUIET ,Time Perception ,Auditory Perception ,Female - Abstract
This report describes three experiments on auditory saltation, studied with click stimuli presented at interclick intervals (ICIs) from 30 to 240 ms. In experiment 1, subjects rated the strength of the saltation illusion evoked by trains of six monaural clicks (i.e., three presented to one ear followed by three to the other ear), and six dichotic clicks on which were imposed either a 500-micros interaural time difference or a 9-dB interaural level difference (ILD). The interaural disparity of theclicks was reversed at the midpoint of the train. Subjects reported equivalent strengths of saltation for the dichotic clicks, but weaker saltation for the monaural ones. These data indicated that saltation is supported by dichotic clicks, regardless of the stimulus manipulation used to generate the lateralized images. In experiment 2, subjects rated the strength of the saltation evoked by six click trains lateralized, in separate trials, by ILDs ranging from 9 to 30 dB, and by a train of monaural clicks. In all ILD conditions, the level of the clicks at the "quiet" ear was above click-detection threshold when presented monaurally. Saltation weakened with increasing ILD, and approximated that seen with monaural clicks when the ILD was 30 dB. These data indicated that for the range of ICIs used here, saltation weakened as the stimuli became more strongly lateralized. In experiment 3, the number of dichotic clicks preceding the disparity reversal was, in separate trials, varied from 3 to 10, and subjects were asked to detect the presence of spatial stationarity in the click train. By plotting the subjective ratings as a function of the length of the leading click train, it was shown that the temporal window within which the saltation effect operates varies between listeners, but is usually less than about 350-400 ms.
- Published
- 2001
30. Auditory Gap Detection, Perceptual Channels, and Temporal Resolution in Speech Perception
- Author
-
Dennis P. Phillips
- Subjects
Speech and Hearing - Abstract
This article overviews some recent advances in our understanding of temporal processes in auditory perception. It begins with the premise that hearing is the online perceptual elaboration of acoustic events distributed in time. It examines studies of gap detection for two reasons: first, to probe the temporal acuity of auditory perception in its own right and, second, to show how studies of gap detection have provided new insights into the processes involved in speech perception and into the architecture of auditory spatial perceptual mechanisms. The implications of these new data for our comprehension of some central auditory processing disorders are examined. Abbreviations: SLI = specific language impairment, VOT = voice onset time
- Published
- 1999
31. Response magnitude and timing of auditory response initiation in the inferior colliculus of the awake chinchilla
- Author
-
Robert Burkard and Dennis P. Phillips
- Subjects
Male ,Inferior colliculus ,Tone burst ,medicine.medical_specialty ,Time Factors ,genetic structures ,Acoustics and Ultrasonics ,Auditory response ,Acoustics ,Biology ,Stimulus (physiology) ,Audiology ,Arts and Humanities (miscellaneous) ,Chinchilla ,medicine ,Animals ,Wakefulness ,CATS ,Auditory Threshold ,Noise burst ,Inferior Colliculi ,Amplitude ,Rise time ,Time Perception ,Auditory Perception ,Female - Abstract
Recent single-unit studies in anesthetized cats have revealed that the latency and strength of transient responses to tone burst stimuli are determined largely by stimulus events in the first few ms of the signal. The present study sought to extend these findings by studying the inferior colliculus potential (ICP) in unanesthetized chinchillas. The ICP magnitude and latency were studied as a function of the plateau amplitude and rise time of noise burst stimuli. ICP amplitude increased with stimulus amplitude and decreased with stimulus rise time. ICP latency decreased with stimulus amplitude and increased with stimulus rise time. The absolute values of the ICP latencies confirmed that it is only the first few ms of the stimulus which determine the timing of response initiation, and therefore, that it is not the plateau level of the stimulus that directly determines the latent period. These data constitute a direct link between earlier single-unit studies in anesthetized animals and brainstem-evoked potential data in animals and man.
- Published
- 1999
32. Deficits in Auditory Temporals Resolution Revealed by a Comparison of Word Recognition Under Interrupted and Continuous Noise Masking
- Author
-
Dennis P. Phillips and Andrew Stuart
- Subjects
Masking (art) ,Speech and Hearing ,Computer science ,Speech recognition ,Word recognition ,Resolution (electron density) ,Continuous noise - Published
- 1998
33. Sensory Representations, the Auditory Cortex, and Speech Perception
- Author
-
Dennis P. Phillips
- Subjects
medicine.medical_specialty ,Speech perception ,Crossmodal ,media_common.quotation_subject ,Sensory system ,Auditory phonetics ,Audiology ,Auditory cortex ,Speech and Hearing ,Perception ,medicine ,Auditory imagery ,Neurocomputational speech processing ,Psychology ,media_common - Published
- 1998
34. Factors shaping the response latencies of neurons in the cat's auditory cortex
- Author
-
Dennis P. Phillips
- Subjects
Auditory Cortex ,Neurons ,Mean and predicted response ,Auditory Threshold ,Models, Psychological ,Stimulus (physiology) ,Auditory cortex ,Sound intensity ,Electrophysiology ,Behavioral Neuroscience ,Acoustic Stimulation ,Rise time ,Cats ,Animals ,Threshold model ,Psychology ,Neural coding ,Neuroscience - Abstract
This article addresses two issues. Firstly, the hypothesis that response latency might be a neural code for tone frequency was examined in single-neuron data from the primary auditory cortex of anesthetized cats. Minimal response latencies for characteristic frequency (CF) tones were independent of neural CF. Mean response latencies for a constant amplitude CF tone were also independent of CF. These data, and the fact that cortical neurons do not have an obvious independent referent for stimulus onset time, do not support the view that latency is a code for frequency. Secondly, to investigate a simple threshold model of spike initiation time, we describe the prolongations of response latency with increases in stimulus rise time and their dependence on the peak amplitude of the stimulus. These data show that in cortical neurons, it is not the peak stimulus intensity which determines first-spike latency, and second, that the response latencies are systematically not those expected on the basis of a simple threshold model.
- Published
- 1998
35. Detection of silent intervals between noises activating different perceptual channels: Some properties of 'central' auditory gap detection
- Author
-
J. E. Mossop, Susan E. Hall, Dennis P. Phillips, Michele M. Carr, and T. L. Taylor
- Subjects
Adult ,Male ,Sound Spectrography ,Acoustics and Ultrasonics ,Computer science ,Loudness Perception ,Acoustics ,media_common.quotation_subject ,Stimulus (physiology) ,Pitch Discrimination ,Arts and Humanities (miscellaneous) ,Phonetics ,Reference Values ,Perception ,Stop consonant ,Reaction Time ,Humans ,Attention ,media_common ,Voice-onset time ,Auditory Threshold ,Gap detection ,Speech Perception ,Female ,Psychoacoustics ,Communication channel - Abstract
This article describes four experiments on gap detection by normal listeners, with the general goal being to examine the consequences of using noises in different perceptual channels to delimit a silent temporal gap to be detected. In experiment 1, subjects were presented with pairs of narrow-band noise sequences. The leading element in each pair had a center frequency of 2 kHz and the trailing element's center frequency was parametrically varied. Gap detection thresholds became increasingly poor, sometimes by up to an order of magnitude, as the spectral disparity was increased between the noise bursts that marked the gap. These data suggested that gap-detection performance is impoverished when the underlying perceptual timing operation requires a comparison of activity in different perceptual channels rather than a discontinuity detection within a given channel. In experiment 2, we assessed the effect of leading-element duration in within-channel and between-channel gap detection tasks. Gap detection thresholds rose when the duration of the leading element was less than about 30 ms, but only in the between-channel case. In experiment 3, the gap-detection stimulus was redesigned so that we could probe the perceptual mechanisms that might be involved in stop consonant discrimination. The leading element was a wideband noise burst, and the trailing element was a 300-ms bandpassed noise centered on 1.0 kHz. The independent variable was the duration of the leading element, and the dependent variable was the smallest detectable gap between the elements. When the leading element was short in duration (5-10 ms), gap thresholds were close to 30 ms, which is close to the voice onset time that parses some voiced from unvoiced stop consonants. In experiment 4, the generality of the leading-element duration effect in between-channel gap detection was examined. Spectrally identical noises defining the leading and trailing edges of the gap were presented to the same or to different ears. There was a leading-element duration effect only for the between channel case. The mean gap threshold was again close to 30 ms for short leading-element durations. Taken together, the data suggest that gap detection requiring a temporal correlation of activity in different perceptual channels is a fundamentally different task to the discontinuity detection used to execute gap detection performance in the traditional, within-channel paradigm.
- Published
- 1997
36. Stimulus-induced spike bursts in two fields of cat auditory cortex
- Author
-
Susan E. Hall, Malcolm N. Semple, L. M. Kitzes, and Dennis P. Phillips
- Subjects
Electrophysiology ,CATS ,medicine.anatomical_structure ,Central nervous system ,Carnivora ,medicine ,Neuron ,Stimulus (physiology) ,Psychology ,Inhibitory postsynaptic potential ,Auditory cortex ,Neuroscience ,Sensory Systems - Abstract
The sound-evoked responses of extracellularly recorded cat primary auditory cortical neurons usually consist of a single spike or a short-term burst of 2-4 spikes, irrespective of the nature of the acoustic signal. In the cat's auditory cortex, the properties of such responses have to date been described only for cells in the primary field (AI). The purpose of the present study was to describe the properties of stimulus-evoked spike-burst responses seen in neurons of the posterior auditory field (P) and to compare those properties with those of a sample of AI neurons studied under similar conditions. The data come from 80 field P and 31 AI neurons studied with tonal and noise-burst stimuli in barbiturate-anesthetized cats, using calibrated, sealed stimulus delivery systems and conventional extracellular recording techniques. The mean inter-spike intervals (ISI) seen in the transient burst responses of posterior field cells were typically short (2-5 ms) and, where it was possible to test them, independent of the rise time of tonal signals, suggesting that they were also independent of the onset spectrum of the stimulus. The mean ISIs were often independent of the stimulus amplitude, even though the signal level had profound effects on the number of spikes evoked and the latency and regularity with which the responses were initiated. Each neuron was assigned a 'characteristic ISI', i.e., the mean ISI seen in the most vigorous responses. The distribution of characteristic ISIs for AI and P neurons overlapped, but were significantly different, with the characteristic ISIs of field P neurons being longer. In both AI and P populations, characteristic ISI was significantly correlated with minimal first-spike latency. The slopes of the regression lines of characteristic ISI on minimal latency for AI and for P cells were not significantly different from each other. Since the minimal latencies of AI neurons were usually shorter than those of field P neurons, the shorter characteristic ISIs of AI cells may thus be interpreted as secondary to their shorter latent periods. The general properties of stimulus-evoked spike bursts seen in field P neurons were thus very similar those previously described for AI cells. These data are consistent with the view that the majority of extracellular recordings in the cat's auditory cortex come from pyramidal neurons and are appropriate as a specialization for transfer of information to nonpyramidal, inhibitory interneurons.
- Published
- 1996
37. Central Auditory Processing
- Author
-
Dennis P. Phillips, Hugh W. Catts, Rachel E. Stark, Diane Paul-Brown, Judith R. Johnston, Paula Tallal, Chie Higuchi Craig, Nina Kraus, Thomas F. Campbell, Maureen E. Thompson, Christine Sloan, Charles S. Watson, Frank E. Musiek, Gail D. Chermak, Donald A. Robin, Jeanane M. Ferre, Malcolm R. McNeil, and Robert W. Keith
- Subjects
Central Auditory Processing Disorder ,Clinical Practice ,Speech and Hearing ,medicine.medical_specialty ,Task force ,Speech recognition ,Intervention (counseling) ,medicine ,Central auditory processing ,Audiology ,Psychology ,Consensus development ,Cognitive psychology - Published
- 1996
38. Factors shaping the tone level sensitivity of single neurons in posterior field of cat auditory cortex
- Author
-
L. M. Kitzes, Dennis P. Phillips, and Malcolm N. Semple
- Subjects
Auditory Cortex ,Neurons ,Field (physics) ,Physiology ,General Neuroscience ,Action Potentials ,Auditory cortex ,Tone (musical instrument) ,Sound ,Sensory Thresholds ,Auditory Perception ,Cats ,Animals ,Female ,Noise ,Psychology ,Neuroscience ,Sensitivity (electronics) - Abstract
1. The posterior field (field P) of the cat's auditory cortex contains a higher proportion of neurons whose response/level functions for characteristic frequency (CF) tones are nonmonotonic than does the primary field (AI). The general purpose of the present study is to assess whether the response/level functions of field P neurons are generated by the same mechanisms as those of cells in AI. All of the data came from single neurons in the cortices of barbiturate-anesthetized cats, to which we presented tonal stimuli through sealed, calibrated stimulating systems. 2. We obtained quantitative data from 123 neurons, of which 108 were located in field P. Of the 108 field P cells, 70% had nonmonotonic response/level functions for 5-ms rise time tones of CF. For cells of any given CF, both CF thresholds and best SPLs (i.e., SPLs associated with maximal responses) varied widely. A correlation analysis revealed that a linear relation between best SPL and CF threshold accounted for 73% of the data variance in the association between those response variables. An analysis of data from 83 nonmonotonic cells in AI revealed a similar relation. 3. Field P neurons whose response/level functions were non-monotonic for 5-ms rise time CF tones became even more narrowly tuned to SPL when the rise time of the tone bursts was reduced to 1 ms. Lengthening the rise time to 20 ms reduced or eliminated the SPL tuning in almost all of these neurons. The general form of monotonic tone response/level functions was commonly unaffected by variation in signal rise time. In a few instances, cells with monotonic response/level functions for 5- and 20-ms rise time tones developed nonmonotonic functions for 1-ms rise time tones. 4. Field P neurons with nonmonotonic response/level functions for CF tones usually failed to respond to wideband noise pulses, or, less commonly, responded to noise only at low SPLs. In contrast, field P cells with a monotonic response to CF tones usually responded monotonically to noise. 5. The minimal mean first-spike latencies of field P neurons were generally longer than those of AI cells studied under similar conditions. The precision of first-spike timing, measured using the SD of the mean first-spike latency, was commonly poorer than that of AI cells. 6. The properties of field P cells followed the same rules as those seen in AI.(ABSTRACT TRUNCATED AT 400 WORDS)
- Published
- 1995
39. Economics and practice management issues associated with acute pain management
- Author
-
Dennis P. Phillips, Brian A. Williams, and Tara L. Knizner
- Subjects
medicine.medical_specialty ,Cost-Benefit Analysis ,Practice management ,Cancer recurrence ,Pacu ,Anesthesia, Conduction ,Medicine ,Humans ,Pain Management ,Intensive care medicine ,Acute pain ,Ultrasonography, Interventional ,biology ,business.industry ,Postsurgical pain ,General Medicine ,Length of Stay ,biology.organism_classification ,Anesthesiology and Pain Medicine ,Regional anesthesia ,Cost utility ,Acute Disease ,Postoperative Nausea and Vomiting ,Physical therapy ,Cost benefit ,Neoplasm Recurrence, Local ,business - Abstract
The use of regional anesthesia (RA) improves cost benefit (hospital-centered) and cost utility (patient-centered) over general anesthesia with volatile agents (GAVA), based upon research in outpatient populations. To make the cost savings a reality, the authors recommend: (1) avoidance of GAVA or at least volatile agents, (2) adopting published postanesthesia care unit (PACU)-bypass criteria conducive to RA, (3) maximizing PACU-bypass rates, and (4) utilizing a block induction area. Inpatient-based acute pain services are not uniform, which makes cost analyses and comparison between practices unreliable. Additional review and commentary address surgical site infections, cancer recurrence, blood transfusions, and chronic postsurgical pain.
- Published
- 2011
40. The Commissural Auditory System
- Author
-
Troy A. Hackett and Dennis P. Phillips
- Subjects
medicine.anatomical_structure ,Modalities ,Binaural processing ,Perception ,media_common.quotation_subject ,Sensation ,Forebrain ,medicine ,Auditory system ,Commissure ,Psychology ,Neuroscience ,media_common - Abstract
We consider the anatomy and the function of the forebrain auditory callosal system. We begin with an anatomical description of callosal organization, drawing on comparative evidence, present evidence for common principles and area-specific departures from these in audition and other modalities, and consider this system in its own right. We also consider experience-dependent development of commissural connectivity and how it is perturbed by experience and disease. We then explore the functional correlates of this anatomical organization with particular attention to the empirical link between callosal and intrahemispheric connectivity on the one hand, and binaural processing on the other. We conclude by exploring the hypothesis that callosal connectivity supports continuity of sensation across the midline to create perceptual unity.
- Published
- 2010
41. Sensitivity of the human binaural cortical steady state response to interaural level differences
- Author
-
Manohar Bance, Dennis P. Phillips, Aaron J. Newman, Steve Aiken, and Sarah Massoud
- Subjects
Sound localization ,Male ,medicine.medical_specialty ,Steady state (electronics) ,Acoustics ,media_common.quotation_subject ,Stimulus (physiology) ,Audiology ,Asymmetry ,Functional Laterality ,Dichotic Listening Tests ,Speech and Hearing ,symbols.namesake ,Young Adult ,Reference Values ,medicine ,Humans ,media_common ,Auditory Cortex ,medicine.diagnostic_test ,Dichotic listening ,Auditory Threshold ,Audiometry, Evoked Response ,Otorhinolaryngology ,Acoustic Stimulation ,Gaussian noise ,symbols ,Female ,Audiometry ,Psychology ,Binaural recording - Abstract
Objectives Periodic alternations of the interaural correlation of a noise stimulus evoke an auditory steady state response that can be measured at the scalp, providing an objective measure of binaural integration. The purpose of this study was to examine the effect of interaural level differences on this steady state response. Design Auditory steady state responses at 4 and 8 Hz were recorded to 4 Hz cycles of interaural correlation change of a Gaussian noise in normal-hearing listeners. Responses were recorded with symmetric presentation levels of 80, 60, and 40 dB SPL and with interaural asymmetries ranging from 10 to 40 dB, varying in 10-dB steps. Results The 8 Hz response was sensitive to interaural level asymmetry and fell to 50% strength at an asymmetry of 18 dB, although the response was detectable to an asymmetry of 30 dB. A simultaneously present 4 Hz response showed no sensitivity to interaural level difference. Significant responses were recorded in all participants. Conclusions The 8 Hz auditory steady state response to a 4 Hz change in noise interaural correlation might be useful as an objective measure of binaural integration in asymmetric hearing loss. Response amplitude is more negatively affected by small amounts of interaural asymmetry than by large reductions in overall presentation level.
- Published
- 2010
42. A midline azimuthal channel in human spatial hearing
- Author
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Susan E. Hall, Dennis P. Phillips, and Rachel N. Dingle
- Subjects
Sound localization ,Adult ,medicine.medical_specialty ,Auditory Pathways ,Time Factors ,media_common.quotation_subject ,Stimulus (physiology) ,Audiology ,Models, Psychological ,Young Adult ,Audiometry ,Hearing ,Perception ,medicine ,Humans ,Sound Localization ,media_common ,Auditory Threshold ,Neurophysiology ,Middle Aged ,Sensory Systems ,Azimuth ,Acoustic Stimulation ,Auditory localization ,Sound sources ,Psychology ,Communication channel ,Psychoacoustics - Abstract
Neurophysiological and psychophysical evidence has driven the formulation of a hemifield model of mammalian sound localization in which the perceived location of a stimulus is based on the relative activity of two hemifield-tuned azimuthal channels that are broadly responsive to contralateral auditory space and have overlapping medial borders. However, neurophysiological work in mammals has consistently found neurons selective for sound sources at the midline, which may indicate the existence of a third, ‘midline’, perceptual channel. In three experiments, the existence of three (left, right, midline) perceptual channels for azimuth in man was examined using auditory selective adaptation paradigms. If no midline channel exists, exposure to highly lateralized, symmetrical adaptator frequencies should not result in a shift in the perceived intracranial location of subsequent test tones away from the adaptors because the relative activation of the two hemifield channels will remain the same. Rather, our results indicate a shift in perceived test tones towards the azimuthal midline. This result can best be explained by a perceptual/neural channel tuned to sounds located along the midline. The present study gives the first psychophysical evidence of a midline channel serving human auditory localization, adding to the earlier evidence on the same point from animal neurophysiological studies.
- Published
- 2010
43. Effects of Continuous Noise Maskers on Tone-evoked Potentials in Cat Primary Auditory Cortex
- Author
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Dennis P. Phillips and Jack B. Kelly
- Subjects
medicine.medical_specialty ,Cognitive Neuroscience ,Auditory area ,Perceptual Masking ,Stimulus (physiology) ,Audiology ,Auditory cortex ,behavioral disciplines and activities ,Functional Laterality ,Cellular and Molecular Neuroscience ,otorhinolaryngologic diseases ,medicine ,Animals ,Evoked potential ,Mathematics ,Auditory Cortex ,Auditory masking ,Auditory Threshold ,Ear ,Continuous noise ,Acoustic Stimulation ,Cats ,Evoked Potentials, Auditory ,sense organs ,Binaural recording ,psychological phenomena and processes - Abstract
In nine barbiturate-anesthetized cats, cortical evoked potentials for tones presented to the contralateral ear were studied for the effects of continuous wideband noise masking. In five animals, input-output functions for tones were obtained in the presence of continuous noise masking at the same ear. Tone thresholds were raised by the presence of the masker, and they closely tracked the level of the masker, such that increments in masker level brought about tone threshold elevations of the same magnitude. In four animals, we compared the effect on responses to contralateral tones of continuous maskers presented to the same ear as the tone, to the opposite ear, and to both ears simultaneously. The presence of the masker at the ear opposite the tone had a small and variable effect on the response to the stimulus at the ear with the tone, whether or not noise was also present at that ear. Consideration of extant single-neuron evidence provides an interpretation of these findings. Whereas maskers at the ear with the tone are known to reduce signal sensitivity for almost all cortical neurons, the effects of masking at the ear opposite the tone (ipsilateral to the cortex) are likely to be very heterogeneous. It is likely that the perceptual salience of signals that have different binaural configurations to concurrent maskers resides in which neuronal elements are activated, rather than in the total number of cells excited, and it is perhaps for this reason that the evoked potentials show only modest effects of this masking parameter.
- Published
- 1992
44. Food caching in captive coyotes: Stereotypy of action sequence and spatial distribution of cache sites
- Author
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J. Ryon, W. Danilchuk, John C. Fentress, and Dennis P. Phillips
- Subjects
Male ,Appetitive Behavior ,Communication ,business.industry ,Carnivora ,Spatial Behavior ,Zoology ,Captivity ,Body movement ,General Medicine ,Motor Activity ,Social Environment ,Spatial distribution ,Stereotypy (non-human) ,Feeding behavior ,Orientation ,Animals ,Female ,Motor activity ,Cache ,Stereotyped Behavior ,Psychology ,business ,Hoarding (animal behavior) - Abstract
This paper describes some aspects of the food caching behaviour of four captive coyotes. Detailed observations of the actions used by coyotes to cache food revealed them to be strikingly similar to those previously described for timber wolves. The similarities included the identity of the movements used, their temporal sequencing, and their susceptibility to interruption. This suggests that there exists a stereotypy across canids in the action sequences used in caching. Second, an examination of the distribution of cache sites revealed that each coyote scattered cache sites widely within a wooded region of their enclosure and preferentially in terrains close to exposed tree roots.
- Published
- 1991
45. SPECTRAL ANALYSIS OF NEONATAL WOLFCANIS LUPUSVOCALIZATIONS
- Author
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Elizabeth M. Coscia, John C. Fentress, and Dennis P. Phillips
- Subjects
Litter (animal) ,medicine.medical_specialty ,Communication ,Ecology ,biology ,business.industry ,Captivity ,Monitoring system ,Audiology ,biology.organism_classification ,Close range ,Canis ,otorhinolaryngologic diseases ,medicine ,Animal behavior ,Spectral analysis ,Animal communication ,business ,Ecology, Evolution, Behavior and Systematics - Abstract
Timber wolf Canis lupus pups vocalize within hours of birth. In this report we examine aspects of the acoustical structure of these vocalizations. We installed an unobtrusive monitoring system in a den excavated by a group of pack-reared timber wolves at the Dalhousie Animal Behavior Field Station in order to observe and record at close range the activities of a female wolf with her litter of pups. We obtained audio and video recordings from birth through the first six postnatal weeks, after which time the pups emerged from the den. The audio recordings were analyzed spectrographically and the vocalizations were classified according to gross spectral type, duration, presence and rate of frequency modulation, and spectral bandwidth. Joint differences in at least two dimensions were necessary to classify vocalizations. The most common sounds, present as early as day one, were harmonically structured, with fundamental frequencies that decreased with age. Other vocalizations, which were rare and rese...
- Published
- 1991
46. Ear and contralateral masker effects on auditory temporal gap detection thresholds
- Author
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Dennis P. Phillips, Martha E. Carmichael, and Susan E. Hall
- Subjects
Adult ,Male ,medicine.medical_specialty ,Time Factors ,Adolescent ,Speech recognition ,Audiology ,Lateralization of brain function ,Young Adult ,medicine ,Humans ,Mathematics ,Aged ,Aged, 80 and over ,Significant difference ,Contralateral hemisphere ,Auditory Threshold ,Gap detection ,Middle Aged ,Sensory Systems ,Continuous noise ,Bruit ,Acoustic Stimulation ,Temporal resolution ,Cerebral hemisphere ,Female ,medicine.symptom ,Perceptual Masking - Abstract
A temporal processing advantage is thought to underlie the left hemisphere dominance for language. One measure of a temporal processing advantage is temporal acuity or resolution. A standard paradigm for measuring auditory temporal resolution is gap detection in its "within-channel" and "between-channel" forms. Previous experiments investigating a right ear advantage for within-channel gap detection have yielded conflicting results, and between-channel gap detection has not previously been studied for ear differences. In the present study, the two types of gap detection task were employed, under each of three contralateral masking conditions (no noise, continuous noise and interrupted noise). An adaptive tracking procedure was used to measure the minimal detectable gap at each ear (and therefore, the temporal acuity of the contralateral hemisphere). A significant effect of masking noise was observed in both of the gap detection tasks. Within-channel gap threshold durations were longer in the interrupted noise condition for both ears. Between-channel gap threshold durations were shorter in the interrupted noise condition at the left ear, with a trend in the same direction at the right ear. The study found no significant difference between the ears in thresholds in either gap detection task in any of the masking conditions. This suggests that if the left cerebral hemisphere has a temporal processing advantage, then it is not in the form of acuity for temporal gap detection.
- Published
- 2008
47. Acquired word deafness, and the temporal grain of sound representation in the primary auditory cortex
- Author
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Mary E. Farmer and Dennis P. Phillips
- Subjects
medicine.medical_specialty ,Selective auditory attention ,Auditory Pathways ,Speech perception ,media_common.quotation_subject ,Deafness ,Audiology ,Auditory cortex ,Behavioral Neuroscience ,Speech discrimination ,Perception ,medicine ,Animals ,Humans ,Pitch Perception ,media_common ,Auditory Cortex ,Sound (medical instrument) ,Communication ,business.industry ,Auditory Perceptual Disorders ,Representation (systemics) ,Neurophysiology ,Speech Perception ,Brain Damage, Chronic ,Psychology ,business - Abstract
This paper explores the nature of the processing disorder which underlies the speech discrimination deficit in the syndrome of acquired word deafness following from pathology to the primary auditory cortex. A critical examination of the evidence on this disorder revealed the following. First, the most profound forms of the condition are expressed not only in an isolation of the cerebral linguistic processor from auditory input, but in a failure of even the perceptual elaboration of the relevant sounds. Second, in agreement with earlier studies, we conclude that the perceptual dimension disturbed in word deafness is a temporal one. We argue, however, that it is not a generalized disorder of auditory temporal processing, but one which is largely restricted to the processing of sounds with temporal content in the milliseconds to tens-of-milliseconds time frame. The perceptual elaboration of sounds with temporal content outside that range, in either direction, may survive the disorder. Third, we present neurophysiological evidence that the primary auditory cortex has a special role in the representation of auditory events in that time frame, but not in the representation of auditory events with temporal grains outside that range.
- Published
- 1990
48. Response timing constraints on the cortical representation of sound time structure
- Author
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S. E. Hall and Dennis P. Phillips
- Subjects
Auditory Cortex ,Neurons ,medicine.medical_specialty ,Acoustics and Ultrasonics ,Loudness Perception ,Audiology ,Auditory cortex ,Standard deviation ,Cochlear nucleus ,Pitch Discrimination ,Electrophysiology ,medicine.anatomical_structure ,Arts and Humanities (miscellaneous) ,Cerebral cortex ,Cortex (anatomy) ,Cats ,Evoked Potentials, Auditory ,Reaction Time ,medicine ,Animals ,Latency (engineering) ,Tonotopy ,Arousal ,Mathematics - Abstract
The precision of spike response timing of 94 primary auditory cortex neurons was studied using conventional extracellular recording techniques in barbiturate-anesthetized cats to which tone- and/or noise-burst stimuli were presented using sealed sound delivery systems. Precision of spike timing was indexed using the standard deviation of the first-spike latent period in responses evoked by repeated presentation of tonal stimuli systematically varied in frequency, amplitude, and/or repetition rate. Within a neuron, variability of first-spike timing was usually proportional to the mean first-spike latency, in agreement with previous reports. In cases where there was a systematic relation between the precision of response timing and the mean latency, a linear correlation accounted for up to 90% of the data variance. Across the 94 neurons, standard deviations seen in responses of minimum latency were related to minimal mean latencies, and were typically in the range from 0.15-1.5 ms. The data suggest that responses to transients in the cortex show a precision of spike timing which is only slightly worse than that seen in cochlear-nerve fibers. This, however, is in dramatic contrast to previous evidence on the steady-state temporal response of cortical cells, which is at least an order of magnitude poorer than that seen in auditory-nerve fibers and many cochlear nucleus cells. These observations may be directly relevant to the known consequences of auditory cortex pathology in man.
- Published
- 1990
49. Adaptation of central pitch-specific mechanisms
- Author
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Dennis P. Phillips, Susan E. Hall, Susan J Scovil, and Martha E. Carmichael
- Subjects
Adult ,Psychometrics ,Acoustics ,05 social sciences ,Experimental and Cognitive Psychology ,Interaural time difference ,Adaptation (eye) ,Fundamental frequency ,Adaptation, Physiological ,050105 experimental psychology ,Sensory Systems ,Pitch Discrimination ,03 medical and health sciences ,Ophthalmology ,Tone (musical instrument) ,0302 clinical medicine ,Acoustic Stimulation ,Artificial Intelligence ,Lacking energy ,Harmonic ,Humans ,0501 psychology and cognitive sciences ,Psychology ,030217 neurology & neurosurgery ,Psychoacoustics - Abstract
Three previous psychophysical studies have demonstrated that interaural time difference (ITD) coding mechanisms can undergo frequency-specific, selective adaptation. We sought to determine whether this phenomenon extends to the pitch domain, by employing the same psychophysical paradigm as one used previously, but with harmonic tone complexes lacking energy at the fundamental frequency. Ten normal listeners participated in experiment 1. Psychometric functions for ITDs were obtained for harmonic tone complexes with fundamental frequencies of 110 Hz and 185 Hz, before and after selective adaptation with complexes of the same fundamental frequencies lateralised to opposite sides. In experiment 1, each subject was tested twice. On separate days, subjects were tested with 110 Hz and 185 Hz stimuli that were either partially resolvable complexes or unresolvable ones. Both partially resolved and unresolved stimuli supported adaptation, and at both fundamental frequencies. In experiment 2, which employed nine listeners, the adaptor tone complexes were presented in conjunction with a diotic noise background designed to mask difference tones generated by the adaptor stimuli. The use of the masker had little effect on the mean strength of the adaptation effected by the unresolved adaptor stimuli, and only slightly weakened the adaptation effect found with the partially resolved adaptor stimuli. Taken together, these data constitute the first demonstration of selective adaptation exerted on a central mechanism in the pitch domain.
- Published
- 2007
50. Development of perceptual correlates of reading performance
- Author
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Kerry M. M. Walker, Raymond M. Klein, Dennis P. Phillips, and Susan E. Hall
- Subjects
Auditory perception ,Adult ,Male ,Visual perception ,Time Factors ,Adolescent ,media_common.quotation_subject ,Human Development ,Developmental psychology ,Discrimination, Psychological ,Phonological awareness ,Phonetics ,Reading (process) ,Perception ,medicine ,Humans ,Child ,Molecular Biology ,media_common ,General Neuroscience ,Dyslexia ,Age Factors ,Cognition ,Middle Aged ,medicine.disease ,Reading ,Auditory Perception ,Linear Models ,Visual Perception ,Female ,Neurology (clinical) ,Psychology ,Developmental Biology ,Cognitive psychology - Abstract
Performance on perceptual tasks requiring the discrimination of brief, temporally proximate or temporally varying sensory stimuli (temporal processing tasks) is impaired in some individuals with developmental language disorder and/or dyslexia. Little is known about how these temporal processes in perception develop and how they relate to language and reading performance in the normal population. The present study examined performance on 8 temporal processing tasks and 5 language/reading tasks in 120 unselected readers who varied in age over a range in which reading and phonological awareness were developing. Performance on all temporal processing tasks except coherent motion detection improved over ages 7 years to adulthood (p
- Published
- 2006
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