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The extended-wear hearing aid (EWHA) is a hearing assistive device that combines a low-power analog amplification circuit with a soft biocompatible foam plug that allows it to remain in the ear canal for several months at a time without replacement. EWHAs fit snugly in the ear canal and are not vented and so produce insertion losses comparable to a passive earplug when inserted into the ear canal with the active circuitry turned off. However, EWHAs are not marketed as hearing protection devices, and other than a general warning to users that the device will have impaired auditory awareness when the device is inserted in the "off" mode, relatively little has been reported about the attenuation characteristics of EWHAs. In this study, commercially-available EWHAs were evaluated using the ANSI standard procedures for measuring hearing protector attenuation in impulse noise [ANSI (2010). S1242-2010, Methods for the Measurement of Insertion Loss of Hearing Protective Devices in Continuous or Impulsive Noise Using Microphone-In-Real-Ear or Acoustic Text Fixture Procedures (American National Standards Institute, New York)] and in continuous noise [ANSI (2006). S12.6, Methods for Measuring the Real-Ear Attenuation of Hearing Protectors (American National Standards Institute, New York)]. Attenuation values were also measured in double and triple protection conditions that combined EWHAs with traditional earplugs and earmuffs. The results show that properly-fit EWHAs can provide passive attenuation comparable to conventional passive earplugs, which may make it possible to use them to provide persistent protection from intermittent noise sources.

Recent research has focused on measuring neural correlates of metacognitive judgments in decision and post-decision processes during memory retrieval and categorization. However, many tasks (e.g., stimulus detection) may require monitoring of earlier sensory processing. Here, participants indicated which of two intervals contained an 80-ms pure tone embedded in white noise. One frequency (e.g., 1000 Hz) was presented on ∼80% of all trials (i.e., ‘primary’ trials). Another frequency (e.g., 2500 Hz) was presented on ∼20% of trials (i.e., ‘probe’ trials). The event-related potential (ERP) was used to investigate the processing stages related to confidence. Tone-locked N1, P2, and P3 amplitudes were larger for trials rated with high than low confidence. Interestingly, a P3-like late positivity for the tone-absent interval showed high amplitude for low confidence. No ‘primary’ vs. ‘probe’ differences were found. However, confidence rating differences between primary and probe trials were correlated with N1 and tone-present P3 amplitude differences. We suggest that metacognitive judgments can track both sensory- and decision-related processes (indexed by the N1 and P3, respectively). The particular processes on which confidence judgments are based likely depend upon the task an individual is faced with and the information at hand (e.g., presence or absence of a signal).

Failure to detect change in an auditory scene (i.e., change deafness) has been found to occur with alterations to object identities and the location of objects. Event-related potential (ERP) correl...

Affiliation exchanges are inherent phenomena of academia that underlies some of the structural characteristics of academic institutions. Important questions involving the dynamics of institutions’ prestige, the concentration of funding, the spread of scientific ideas, and interdisciplinarity are all related to which institution academics will move upon completion of their training, or when looking for a better environment to pursue their research endeavors. In this work, we investigated the phenomena of affiliation switches in academia and its relationship with research topics in Computer Science. Drawing from publication data spanning over thirty years, we mapped the connections among academic institutions as networks. We report on the stability of network properties over the years in spite of the exponential growth of Computer Science in recent decades. Additionally, we contextualize the structural properties of networks and topic modeling results with the current academic landscape. Altogether, our results help to characterize the phenomena of academic affiliation exchanges through the macro perspective of network science and natural language processing.

Recent studies have related enhancements of theta- (∼4-8 Hz) and alpha-power (∼8-13 Hz) to listening effort based on parallels between enhancement and task difficulty. In contrast, nonauditory works demonstrate that, although increases in difficulty are initially accompanied by increases in effort, effort decreases when a task becomes so difficult as to exceed one's ability. Given the latter, we examined whether theta- and alpha-power enhancements thought to reflect effortful listening show a quadratic trend across levels of listening difficulty from impossible to easy. Listeners (n = 14) performed an auditory delayed match-to-sample task with frequency-modulated tonal sweeps under impossible, difficult (at ∼70.7% correct threshold), and easy (well above threshold) conditions. Frontal midline theta-power and posterior alpha-power enhancements were observed during the retention interval, with greatest enhancement in the difficult condition. Independent component-based analyses of data suggest that theta-power enhancements stemmed from medial frontal sources at or near the anterior cingulate cortex, whereas alpha-power effects stemmed from occipital cortices. Results support the notion that theta- and alpha-power enhancements reflect effortful cognitive processes during listening, related to auditory working memory and the inhibition of task-irrelevant cortical processing regions, respectively. Theta- and alpha-power dynamics can be used to characterize the cognitive processes that make up effortful listening, including qualitatively different types of listening effort.

The Early Literacy Screener (ELS) is a brief screen for emergent literacy delays in 4- and 5-year-olds. Standard developmental screens may also flag these children. What is the value of adding the ELS? Parents of children aged 4 (n = 45) and 5 (n = 26) years completed the Ages and Stages Questionnaire-3 (ASQ-3), the Survey of Well-Being in Young Children (SWYC), and the ELS. Rates of positive agreement (PA), negative agreement (NA), and overall agreement (Cohen's κ) across the various screening tools were calculated. Early literacy delays were detected in 51% of those who passed the ASQ and 38% of those who passed the SWYC. For ELS versus ASQ, κ = 0.18, PA = 0.36 (95% CI = 0.23-0.51), and NA = 0.83 (95% CI = 0.66-0.92). For ELS versus SWYC, κ = 0.42, PA = 0.61 (95% CI = 0.45-0.75), and NA = 0.82 (95% CI = 0.65-0.92). The ELS adds value by flagging early literacy delays in many children who pass either the ASQ-3 or SWYC.

Recent studies show that pre-stimulus band-specific power and phase in the electroencephalogram (EEG) can predict accuracy on tasks involving the detection of near-threshold stimuli. However, results in the auditory modality have been mixed, and few works have examined pre-stimulus features when more complex decisions are made (e.g. identifying supra-threshold sounds). Further, most auditory studies have used background sounds known to induce oscillatory EEG states, leaving it unclear whether phase predicts accuracy without such background sounds. To address this gap in knowledge, the present study examined pre-stimulus EEG as it relates to accuracy in a tone pattern identification task. On each trial, participants heard a triad of 40-ms sinusoidal tones (separated by 40-ms intervals), one of which was at a different frequency than the other two. Participants' task was to indicate the tone pattern (low-low-high, low-high-low, etc.). No background sounds were employed. Using a phase opposition measure based on inter-trial phase consistencies, pre-stimulus 7–10 Hz phase was found to differ between correct and incorrect trials ∼200 to 100 ms prior to tone-pattern onset. After sorting trials into bins based on phase, accuracy was found to be lowest at around π − + relative to individuals’ most accurate phase bin. No significant effects were found for pre-stimulus power. In the context of the literature, findings suggest an important relationship between the complexity of task demands and pre-stimulus activity within the auditory domain. Results also raise interesting questions about the role of induced oscillatory states or rhythmic processing modes in obtaining pre-stimulus effects of phase in auditory tasks.

An important application of cognitive architectures is to provide human performance models that capture psychological mechanisms in a form that can be "programmed" to predict task performance of human-machine system designs. Although many aspects of human performance have been successfully modeled in this approach, accounting for multitalker speech task performance is a novel problem. This article presents a model for performance in a two-talker task that incorporates concepts from psychoacoustics, in particular, masking effects and stream formation.

Auditory detection can improve with practice. These improvements are often assumed to arise from selective attention processes, but longer-term plasticity as a result of training may also play a role. Here, listeners were trained to detect either an 861-Hz or 1058-Hz tone (counterbalanced across participants) presented in noise at SNRs varying from -10 to -24 dB. On the following day, they were tasked with detecting 861-Hz and 1058-Hz tones at an SNR of -21 dB. In between blocks of this active task, EEG was recorded during passive presentation of trained and untrained frequency tones in quiet. Detection accuracy and confidence ratings were higher for trials at listeners’ trained, than untrained-frequency (i.e., learning occurred). During passive exposure to sounds, the P2 component of the auditory evoked potential (∼150 – 200 ms post tone onset) was larger in amplitude for the trained compared to the untrained frequency. An analysis of global field power similarly yielded a stronger response for trained tones in the P2 time window. These effects were obtained during passive exposure, suggesting that training induced improvements in detection are not solely related to changes in selective attention. Rather, there may be an important role for changes in the long-term neural representations of sounds.

When competing speech sounds are spatially separated, listeners can make use of the ear with the better target-to-masker ratio. Recent studies showed that listeners with normal hearing are able to efficiently make use of this “better-ear,” even when it alternates between left and right ears at different times in different frequency bands, which may contribute to the ability to listen in spatialized speech mixtures. In the present study, better-ear glimpsing in listeners with bilateral sensorineural hearing impairment, who perform poorly in spatialized speech mixtures, was investigated. The results suggest that this deficit is not related to better-ear glimpsing.

Recent studies demonstrate that frontal midline theta power (4–8 Hz) enhancements in the electroencephalogram (EEG) relate to effortful listening. It has been proposed that these enhancements reflect working memory demands. Here, the need to retain auditory information in working memory was manipulated in a 2-interval 2-alternative forced-choice delayed pitch discrimination task (“Which interval contained the higher pitch?”). On each trial, two square wave stimuli differing in pitch at an individual's ∼70.7% correct threshold were separated by a 3-second ISI. In a ‘Roving’ condition, the lowest pitch stimulus was randomly selected on each trial (uniform distribution from 840 to 1160 Hz). In a ‘Fixed’ condition, the lowest pitch was always 979 Hz. Critically, the ‘Fixed’ condition allowed one to know the correct response immediately following the first stimulus (e.g., if the first stimulus is 979 Hz, the second must be higher). In contrast, the ‘Roving’ condition required retention of the first tone for comparison to the second. Frontal midline theta enhancements during the ISI were only observed for the ‘Roving’ condition. Alpha (8–13 Hz) enhancements were apparent during the ISI, but did not differ significantly between conditions. Since conditions were matched for accuracy at threshold, results suggest that frontal midline theta enhancements will not always accompany difficult listening. Mixed results in the literature regarding frontal midline theta enhancements may be related to differences between tasks in regards to working memory demands. Alpha enhancements may reflect task general effortful listening processes.

Head-related transfer functions (HRTFs) capture location dependent alterations to a sound caused by a physical interaction with a listener's head, shoulders, and outer ears. Sounds rendered with a listener's own HRTF can be localized with accuracy comparable to real sources; however, because anthropometric features vary across listeners, rendering sounds with non-individualized HRTFs can severely degrade localization of virtual sound source location, especially in elevation. Here, we were interested in identifying event-related potential (ERP) features associated with the benefit of employing individualized HRTFs. Thirty “runs” of 250 ms white-noise bursts (6–12 bursts long) with identical virtual elevations (0°–90°, 10° increments) were presented back-to-back within a block. Listeners were instructed to press a button whenever the elevation changed (i.e., at the start of each run). Elevation change detection was enhanced in an Individualized compared to a non-Individualized HRTF condition. ERPs to first bursts of a run showed larger amplitude P3s in the Individualized HRTF condition. Differences in P3 amplitudes between conditions were positively correlated with behavioral benefits gained from employing an individualized HRTF. That effects occurred for the P3 suggests that at least part of the benefit obtained from using individualized HRTFs reflects post-sensory processes.

Auditory detection can improve with training. Though the majority of theorists posit that such improvements relate to dynamics of selective attention, longer-term sensory plasticity may also play a role (e.g., increased cortical processing for trained sounds). Here, listeners were trained in a single session to detect either an 861-Hz or 1058-Hz tone (counterbalanced across participants) presented in a frozen white noise masker. On the following day, EEG was collected while listeners: 1) attempted to detect 861-Hz and 1058-Hz tones at an SNR of -21 dB, and 2) passively heard the same tones presented in quiet. Listeners were significantly better at detecting tones at their trained frequency. In addition, P3 amplitudes were larger for trained than for untrained tones during the active detection task. During passive exposure to the same tones, P2 amplitudes were similarly larger for trained than for untrained tones. The difference in P3 amplitudes suggests that training leads to more efficient post-sensory p...

An important application of cognitive architectures is to provide human performance models that capture psychological mechanisms in a form that can be “programmed” to predict task performance of human-machine system designs. While many aspects of human performance have been successfully modeled in this approach, accounting for multi-talker speech task performance is a novel problem. This paper presents a model for performance in a two-talker task that incorporates concepts from the psychoacoustic study of speech perception, in particular, masking effects and stream formation.

Prematurity is the biggest contributor to admissions in the neonatal intensive care unit (NICU). The period following hospital discharge is a vital continuum for the very low birth weight (VLBW) infant. The objective of this study was to assess the impact of a unique discharge and follow-up process on the outcomes of VLBW infants leaving the NICU.All outpatient health care usage by VLBW infants born in the study year (cases) was retrospectively tracked through 12 months of age. A cohort of healthy newborn infants were matched by birthdate to each VLBW infant (controls) and similarly tracked.In this study, there were 85 cases and 85 controls. The mean gestational age at birth for the cases was 29.1 ± 2.7 weeks with a mean birth weight of 1079 ± 263 g. That of the controls was 38.9 ± 1.3 weeks and 3202 ± 447 g. Over 90% of both populations had Medicaid coverage. All VLBW infants received care at the Special Care Developmental Follow-Up Clinic. When compared with the controls, VLBW infants discharged from the NICU made fewer acute, unscheduled visits to the Emergency Department or Urgent Care Clinic (2.3 ± 2.5 vs. 3.7 ± 3.5; P=0.007) despite their high-risk medical and social status. Their growth pattern showed significant "catch-up" and was similar to the matched controls at the last scheduled visit for each group.Outcomes including health care utilization in high-risk infants can be improved through meticulous discharge planning and follow-up measures that utilize existing hospital infrastructure to provide affordable comprehensive care.

Virtual localization experiments have demonstrated that Head Related Transfer Functions measured a few millimeters inside a blocked ear canal can produce localization performance approaching what is measured in the free field. This suggests that an earplug inserted entirely inside the ear canal should be able to preserve normal localization performance so long as the stimulus is loud enough to overcome any insertion loss in the device at all frequencies. In this study, localization performance of normal-hearing listeners was measured with the Lyric extended wear hearing aid, both in active mode (where it acted like an electronic pass-through earplug) and in passive mode (where it acted like a passive hearing protector). In an active mode, localization accuracy approached the open-ear condition. However, under the passive condition, localization was much worse than with the open ear even at high stimulus levels where the full spectrum should have been audible. This result suggests there may be fundamental limitations on localization accuracy with passive hearing protection that are unrelated to the directionality of the HRTF. [The views expressed in this abstract are those of the authors and do not reflect the official policy of the Department of the Army/Air Force, Department of Defense, or U.S. Government.]Virtual localization experiments have demonstrated that Head Related Transfer Functions measured a few millimeters inside a blocked ear canal can produce localization performance approaching what is measured in the free field. This suggests that an earplug inserted entirely inside the ear canal should be able to preserve normal localization performance so long as the stimulus is loud enough to overcome any insertion loss in the device at all frequencies. In this study, localization performance of normal-hearing listeners was measured with the Lyric extended wear hearing aid, both in active mode (where it acted like an electronic pass-through earplug) and in passive mode (where it acted like a passive hearing protector). In an active mode, localization accuracy approached the open-ear condition. However, under the passive condition, localization was much worse than with the open ear even at high stimulus levels where the full spectrum should have been audible. This result suggests there may be fundamental ...

Nicole is a 15-year-old girl presenting to the Developmental Behavioral Pediatrics Clinic with symptoms of the inattentive type of Attention-Deficit/Hyperactivity Disorder (ADHD) and declining school performance over the last year. She expressed frustration over her inability to concentrate on schoolwork. Assuming that her poor grades were secondary to lack of effort, her parents withdrew privileges. Nicole became increasingly depressed. She stopped participating in activities, she previously enjoyed, and her parents reported that she stopped singing in the shower. After talking to a cousin with ADHD, Nicole concluded that she had ADHD as well. She asked her parents to arrange for an evaluation.Nicole met DSM-5 criteria for the diagnosis of inattentive ADHD and was started on a stimulant medication (mixed amphetamine salts). She had symptoms of a coexisting depression, although she did not meet criteria for diagnosis of a depressive disorder. At a 3-week follow-up visit, she showed improvement in targeted ADHD symptoms; homework was now easier and her grades improved. At a 2-month follow-up, Nicole's weight dropped from 53 kg (47th percentile) prestimulant treatment to 49 kg (31st percentile). She reported appetite suppression after taking the stimulant but did not feel that her eating habits had changed significantly. Her father reported that she had a preference for junk food and snacks. Nicole did not enjoy exercising and did not participate in extracurricular sports.She weighed herself several times a day, as she was worried about losing too much weight. Nicole's mood continued to be low, despite the fact that her grades improved, and her parents were more understanding of her challenges. She was otherwise healthy and reported regular menstrual cycles. Nicole requested an increase in the dose of stimulant medication for greater improvement in concentration during homework and in school.Her pediatric clinician was concerned about the possibility of an eating disorder in addition to depression. She asked herself, "Are we treating inattentive ADHD effectively or are we enabling an eating disorder?"

Auditory cues, when coupled with visual objects, have lead to reduced response times in visual search tasks, suggesting that adding auditory information can potentially aid Air Force operators in complex scenarios. These benefits are substantial when the spatial transformations that one has to make are relatively simple i.e., mapping a 3-D auditory space to a 3-D visual scene. The current study focused on listeners’ abilities to map sound surrounding a listener to a 2-D visual space, by measuring performance in localization tasks that required the following responses: 1) Headpointing: turn and face a loudspeaker from where a sound emanated, 2) Tablet: point to an icon representing a loudspeaker displayed in an array on a 2-D GUI or, 3) Hybrid: turn and face the loudspeaker from where a sound emanated and them indicate that location on a 2-D GUI. Results indicated that listeners’ localization errors were small when the response modality was head-pointing, and localization errors roughly doubled when they were asked to make a complex transformation o fauditory-visual space (i.e., while using a hybrid response); surprisingly, the hybrid response technique reduced errors compared to the tablet response conditions. These results have large implications for the design of auditory displays that require listeners to make complex, non-intuitive transformations of auditory-visual space.

While several potential auditory cues responsible for sound source externalization have been identified, less work has gone into providing a simple and robust way of manipulating perceived externalization. The current work describes a simple approach for parametrically modifying individualized head-related transfer function spectra that results in a systematic change in the perceived externalization of a sound source. Methods and results from a subjective evaluation validating the technique are presented, and further discussion relates the current method to previously identified cues for auditory distance perception.

Although many psychoacoustic studies have been conducted to examine the detection of masked target sounds, the vast majority of these studies have been conducted in carefully controlled laboratory listening environments, and their results may not apply to the detection of real-world sounds in the presence of naturalistic ambient sound fields. Those studies that have examined the detection of realistic naturally-occurring sounds have been conducted in uncontrolled listening environments (i.e., outdoor listening tests) where the experimenters were unable to precisely control, or even measure, the specific characteristics of the target and masker at the time of the detection judgment. This study represents an attempt to bridge the gap between unrealistic laboratory listening studies and uncontrolled outdoor listening studies through the use of pseudorandomly-presented real world recordings of target and masking sounds. Subjects were asked to detect helicopter signals in the context of an ongoing ambient recording in a two interval detection task. The results show that the signal-to-noise ratio required to detect an aircraft sound varies across different types of ambient environments (i.e., rural, suburban, or urban).

The goals of this study were to measure sensitivity to the direct-to-reverberant energy ratio (D∕R) across a wide range of D∕R values and to gain insight into which cues are used in the discrimination process. The main finding is that changes in D∕R are discriminated primarily based on spectral cues. Temporal cues may be used but only when spectral cues are diminished or not available, while sensitivity to interaural cross-correlation is too low to be useful in any of the conditions tested. These findings are based on an acoustic analysis of these variables and the results of two psychophysical experiments. The first experiment employs wideband noise with two values for onset and offset times to determine the D∕R just-noticeable difference at −10, 0, 10, and 20 dB D∕R. This yielded substantially higher sensitivity to D∕R at 0 and 10 dB D∕R (2–3 dB) than has been reported previously, while sensitivity is much lower at −10 and 20 dB D∕R. The second experiment consists of three parts where specific cues to D∕R are reduced or removed, which enabled the specified rank ordering of the cues. The acoustic analysis and psychophysical experiments also provide an explanation for the “auditory horizon effect.”

Speech recognition was measured as a function of the target-to-masker ratio (TMR) with syntactically similar speech maskers. In the first experiment, listeners were instructed to report keywords from the target sentence. Data averaged across listeners showed a plateau in performance below 0 dB TMR when masker and target sentences were from the same talker. In this experiment, some listeners tended to report the target words at all TMRs in accordance with the instructions, while others reported keywords from the louder of the sentences, contrary to the instructions. In the second experiment, stimuli were the same as in the first experiment, but listeners were also instructed to avoid reporting the masker keywords, and a payoff matrix penalizing masker keywords and rewarding target keywords was used. In this experiment, listeners reduced the number of reported masker keywords, and increased the number of reported target keywords overall, and the average data showed a local minimum at 0 dB TMR with same-talker maskers. The best overall performance with a same-talker masker was obtained with a level difference of 9 dB, where listeners achieved near perfect performance when the target was louder, and at least 80% correct performance when the target was the quieter of the two sentences.

Single-sided deafness prevents access to the binaural cues that help normal-hearing listeners extract target speech from competing voices. Little is known about how listeners with one normal-hearing ear might benefit from access to severely degraded audio signals that preserve only envelope information in the second ear. This study investigated whether vocoded masker-envelope information presented to one ear could improve performance for normal-hearing listeners in a multi-talker speech-identification task presented to the other ear. Target speech and speech or non-speech maskers were presented unprocessed to the left ear. The right ear received no signal, or either an unprocessed or eight-channel noise-vocoded copy of the maskers. Presenting the vocoded maskers contralaterally yielded significant masking release from same-gender speech maskers, albeit less than in the unprocessed case, but not from opposite-gender speech, stationary-noise, or modulated-noise maskers. Unmasking also occurred with as few as two vocoder channels and when an attenuated copy of the target signal was added to the maskers before vocoding. These data show that delivering masker-envelope information contralaterally generates masking release in situations where target-masker similarity impedes monaural speech-identification performance. By delivering speech-envelope information to a deaf ear, cochlear implants for single-sided deafness have the potential to produce a similar effect.

When listening to natural speech, listeners are fairly adept at using cues such as pitch, vocal tract length, prosody, and level differences to extract a target speech signal from an interfering speech masker. However, little is known about the cues that listeners might use to segregate synthetic speech signals that retain the intelligibility characteristics of speech but lack many of the features that listeners normally use to segregate competing talkers. In this experiment, intelligibility was measured in a diotic listening task that required the segregation of two simultaneously presented synthetic sentences. Three types of synthetic signals were created: (1) sine-wave speech (SWS); (2) modulated noise-band speech (MNB); and (3) modulated sine-band speech (MSB). The listeners performed worse for all three types of synthetic signals than they did with natural speech signals, particularly at low signal-to-noise ratio (SNR) values. Of the three synthetic signals, the results indicate that SWS signals preserve more of the voice characteristics used for speech segregation than MNB and MSB signals. These findings have implications for cochlear implant users, who rely on signals very similar to MNB speech and thus are likely to have difficulty understanding speech in cocktail-party listening environments.

Attempts to identify physiological correlates of listening effort have mainly focused on peripheral measures (e.g. pupillometry) and auditory-evoked/event-related potentials. Although nonauditory studies have suggested that sustained time-frequency electroencephalographic (EEG) features in the θ-band (4-7 Hz) are correlated with domain-general mental effort, little work has characterized such features during effortful listening. Here, high-density EEG data was collected while listeners performed a sentence-recognition task in noise, the signal-to-noise ratio (SNR) of which varied across blocks. Frontal midline θ (Fmθ), largely driven by sources localized in or near the medial frontal cortex, showed greater power with decreasing SNR and was positively correlated with self-reports of effort. Increased Fmθ was present before speech onset and during speech presentation. Fmθ power also differed across SNRs when including only trials in which all words were recognized, suggesting that the effects were unrelated to performance differences. Results suggest that frontal cortical networks play a larger role in listening as acoustic signals are increasingly masked. Further, sustained time-frequency EEG features may usefully supplement previously used peripheral and event-related potential measures in psychophysiological investigations of effortful listening.

Standard audio headphones are useful in many applications, but they cover the ears of the listener and thus may impair the perception of ambient sounds. Bone-conduction headphones offer a possible alternative, but traditionally their use has been limited to monaural applications due to the high propagation speed of sound in the human skull. Here we show that stereo bone-conduction headsets can be used to provide a limited amount of interaural isolation in a dichotic speech perception task. The results suggest that reliable spatial separation is possible with bone-conduction headsets, but that they probably cannot be used to lateralize signals to extreme left or right apparent locations

Auditory training studies have varied in degree-of-similarity between the training and testing conditions. Some focused testing on the trained task (e.g., Sweetow and Henderson Sabes, 2007), while others addressed whether the training effects generalize to other tasks. The current study used speech and non-speech stimuli to explore how much training in a specific analytical listening task would generalize to performance improvements for another. Naive listeners participated. Percent correct was measured as a function of signal-to-noise ratio (SNR) in pre- and post-tests with the “multiple-bursts same” (MBS) paradigm (Kidd et al., 1994) and the speech-target/speech-masker Coordinate Response Measure (CRM) paradigm. There were three training groups in a between-groups design: 1) training in a masked speech identification task (the CRM) with the competitors varying in f0 separation (Darwin et al., 2003); 2) training in the MBS task with the protected-region (frequency region with no maskers) bandwidth around...

One of the greatest challenges in hearing conservation is providing adequate protection for those listeners who spend most of their time in quiet environments, but are occasionally exposed to high levels of noise that occur at unpredictable times. A classic example of this problem occurs for dismounted soldiers, who rely heavily on their natural hearing acuity to detect threats and opportunities on the battlefield but always face the risk of becoming engaged in a dangerously noisy firefight with little or no warning. One emerging technology that might have application in this domain is the extended-wear hearing aid, which is capable of remaining deep in the ear canal for weeks or months before being removed. Preliminary results suggest that the extended wear earplug can provide protection from blast or continuous noise that is comparable to a conventional earplug or muff, and that it can provide detection and localization performance comparable to that achieved with the open ear. Its form factor also make...

Listener performance in an auditory detection task can improve with practice (Zwislocki, Maire, Feldman, & Rubin, 1958). This could result from a selective attention process and/or sensory plasticity (e.g., if trained stimuli receive increased cortical representation). Here, listeners were trained to detect either an 861-Hz or 1058-Hz tone (counterbalanced across participants) presented in a noise masker. On the following day, high-density EEG was collected while listeners: 1) attempted to detect 861-Hz and 1058-Hz tones in noise at an SNR of -21 dB, and 2) passively heard the same tones presented in quiet. Listeners were significantly better at detecting tones at their trained frequency. In addition, P3 amplitudes were larger for trained than for untrained tones during the detection task. During passive exposure to the same tones, P2 amplitudes were similarly larger for trained than for untrained tones. The difference in P3 amplitudes suggests that training leads to more efficient decisional processing, ...

Objective. To develop a brief tool for screening of emergent literacy skills in preschool children (3-5 years old) in pediatric clinics. Methods. Parents were given an 8-item questionnaire, and the children were tested with the Get Ready to Read–Revised (GRTR-R) screener. With the GRTR-R score as gold standard, the parent questionnaire was optimized using various combinations of questions and response weights in one half of the sample. The resulting 5-item questionnaire was then validated using the other half of the sample. Results. A total of 203 patients were enrolled. In the validation sample, the 5-item questionnaire had sensitivity and specificity vis-à-vis the GRTR-R of 100% and 78.6% in 5-year-olds (cutoff score of 8) and 78.6% and 68.2% in 4-year-olds (cutoff of 6). The questionnaire did not perform well in 3-year-olds. Conclusion. A very brief parent questionnaire may be useful as a first-line screener for early reading problems.

In order to predict the detectability of broadband acoustic signals, a model must include a means of integrating information across frequencies. There have been several previous studies measuring the detectability of multicomponent signals, but it is still not clear what the best model is when signal components are not equally detectable or equal in level. Some researchers have proposed that thresholds are driven by the most detectable component (max(d') model), while others have found that the best model for their data is a statistical summation model, where component sensitivities are combined using a Pythagorean sum. In the present study, detection thresholds were collected in broadband noise for single tones at three frequencies and three signal-to-noise ratios (SNR) and for all combinations of SNRs for the three tones presented together. While both models (max-d' and Pythagorean sum) can predict the general trend of the multicomponent data from the single-component data, each model only accounts for ...

Previous studies have shown that single-sided-deaf (SSD) patients implanted with cochlear implants (CIs) can receive spatial release-from-masking (SRM), likely due to head-shadowing effects. This study investigated the possibility that SSD-CI patients might also obtain SRM benefits from binaural-integration cues when the target speech is masked by a spatially-separated fluctuating masker. Experiment 1 measured psychometric functions for word-recognition performance in the presence of stationary noise, modulated noise, and one or two same- or opposite-gender interfering talkers. The first ear received an unprocessed mixture containing the target and masker(s). The second ear received no signal (NH/Deaf), an unprocessed mixture containing just the maskers (NH/NH), or a mixture containing just the maskers that was processed with an eight-channel noise vocoder (NH/Vocoder). The results show that SRM occurred in the NH/NH condition for all masker types, but that it only occurred in the SSD/Vocoder condition with same-gender interfering talkers. Experiment 2 revealed that SRM occurred in the NH/Vocoder condition with as few as two vocoder channels, and that maximum performance occurred with six or more channels. These results suggest that CIs for SSD have the potential to produce SRM in situations where monaural cues are insufficient for concurrent speech-stream segregation.

1. We have studied the numerical and functional responses of campanulate morphs of Asplanchna intermedia fed five species of rotifer (Brachionus rubens, B. patulus, B. calyciflorus, Hexarthra mira and Filinia longiseta). The vulnerability of the prey varied with their morphology and mode of swimming. 2. To test the numerical and functional responses, prey species differing in their morphology and mode of swimming were provided. Responses were also tested with mixtures of evasive and non-evasive prey provided in three different ratios. 3. A. intermedia showed a type II functional response to all the prey species provided. 4. The population growth rate of A. intermedia on the various prey species provided ranged from a minimum of –0.24 to a maximum of 0.68. There was a significant correlation between the capturability of a prey species and the population growth rate of the predator feeding on it. The capturability of a prey species also has a significant influence on the maximal predator density but not on the time taken to reach it. 5. Observations from a field study undertaken over a 10-month period to study the prey preferences of A. intermedia in nature were corroborated by the laboratory findings.

We studied the outcome of competition between a large (Brachionus calyciflorus) and a small (Anuraeopsis fissa) rotifer species at five algal (Scenedesmus acutus) concentrations (0.5 × 106 to 40.5 × 106 cells ml−1) and with varying initial densities in mixed populations (100 to 0% of B. calcyciflorus or A. fissa), the combined initial biomass being 0.2 µg ml−1 in all test jars. Experiments were conducted at 28 ± 1 °C.

Previous studies of communication in noisy environment have shown that interlocutors, when residing in the same acoustic environment, continuously adapt their speech patterns in order to overcome communication difficulties (Cooke et al., 2014; Lindblom, 1990). However, little is known about the impact on communication when individuals are in disparate acoustic environments and if/how these individuals would adapt their speech to support effective communication. In this study, eight pairs of interlocutors were required to completed the “spot-the-difference” Diapix task (Van Engel et al., 2010) while being exposed to one of 2 acoustic environments presented at 85 dB SPL over headphones: 1) sparse (2-talker) babble; or 2) dense (8-talker) babble. In some conditions, both individuals were in similar acoustic environments while in others they were in different acoustic environments. A control condition, where both interlocutors communicated in quiet environments was also included. Preliminary results showed th...