Search

To characterize the catchment area and patient profile of large cochlear implant (CI) centers in the United States.Multi-institutional retrospective case series.Tertiary referral CI centers.Patients who underwent CI surgery at 7 participating CI centers between 2015 and 2020 were identified. Patients' residential zip codes were used to approximate travel distances and urban vs rural residential areas.Over the 6-year study period (2015-2020), 6313 unique CI surgical procedures occurred (4529 adult, 1784 pediatric). Between 2015 and 2019, CI procedures increased by 43%. Patients traveled a median 52 miles (interquartile range, 21-110) each way; patients treated at rural CI centers traveled greater distances vs those treated at urban centers (72 vs 46 miles,While large CI centers serve geographically dispersed populations, most patients reside within a 200-mile radius. Strategies to expand CI utilization may leverage remote programming, telemedicine, and strategic placement of new centers and satellite clinics to ameliorate travel burden.

To introduce and discuss implementation strategy for the Complete Cochlear Implant Care (CCIC) model, a highly-coordinated cochlear implant (CI) care delivery model requiring a single on-site visit for preoperative workup, surgery, and postoperative programming.Prospective, nonrandomized, two-arm clinical trial.Tertiary referral CI center.Adults who meet audiologic criteria for cochlear implantation.Cochlear implantation, coordinated care delivery, including remote programming.Care delivery model feasibility and process implementation.Patients determined to be likely CI candidates based on routine audiometry are eligible for enrollment. The CCIC model uses telemedicine and electronic educational materials to prepare patients for same-day on-site consultation with CI surgery, same or next-day activation, and postoperative remote programming for 12 months. Implementation challenges include overcoming inertia related to the implementation of a new clinical workflow, whereas scalability of the CCIC model is limited by current hardware requirements for remote programming technology. A dedicated CCIC process coordinator is critical for overcoming obstacles in implementation and process improvement through feedback and iterative changes. Team and patient-facing materials are included and should be tailored to fit each unique CI program looking to implement CCIC.The CCIC model has the potential to dramatically streamline hearing healthcare delivery. Implementation requires an adaptive approach, as obstacles may vary according to institutional infrastructure and policies.

Background and Purpose After cochlear implantation, metallic artifact can obscure nearby structures on CT images, which is problematic in patients with facial nerve stimulation (FNS). This study evaluated the usefulness of co-registered pre- and post-operative examinations to evaluate the cochlear implant and adjacent structures. Materials and Methods A retrospective review was completed of consecutive patients that underwent CT imaging of the temporal bone before and after placement of a cochlear implant. Two blinded neuroradiologists independently reviewed all available examinations. All examinations were assessed for the presence or absence of dehiscence of the osseous ridge between the cochlea and facial nerve canal (FNC). Pre-operative and fused pre- and post-operative examinations were compared in their ability to visualize the osseous ridge using a 5-point Likert scale (ranging from 1 = unfused images were substantially superior to 5 = fused images were substantially superior). The electrode closest to the FNC were noted. Results Of 34 included patients, 13 (38.2%) were female and 21 (61.8%) were male; average age was 72.2. Seven patients (20.6%) had frank dehiscence between the cochlea and FNC. Fused images were superior to the post-operative study alone for assessing the integrity of the osseous partition between the cochlea and FNC and for reducing artifact from the electrode array (average Likert scores for both reviewers were 4.4 and 4.7). There was good agreement between reviewers in noting electrode closest to the FNC (concordance correlation coefficient=0.82). Conclusions Following cochlear implantation, co-registered pre- and post-operative CT images are superior to conventional images in assessing the anatomic relationship between the cochlea and FNC.

To report the novel use of intraoperative electrically evoked stapedial reflex (eSR) for cochlear nerve monitoring during simultaneous translabyrinthine resection of vestibular schwannoma (VS) and cochlear implantation.Clinical capsule report with video demonstration.Tertiary academic referral center.A 58-year-old female presented with a small right intracanalicular VS with associated asymmetrical right moderate to severe sensorineural hearing loss, poor word recognition, tinnitus, and disequilibrium. Based on patient symptomatology and goals, simultaneous CI with translabyrinthine resection of the VS was performed.Cochlear implantation before the tumor was resected facilitated intraoperative eSRs by delivering repeated single-electrode stimulations through the cochlear implant (CI) electrode during tumor resection. A pulse duration of 50-us and a current amplitude of 200-CL or 648-us was used to elicit eSRs visible through the facial recess. Intraoperative eSR was monitored in conjunction with electrically evoked compound action potentials via neural response telemetry and electrical auditory brainstem response.Despite the transient evoked compound action potentials amplitude and electrical auditory brainstem response latency changes, the visually observed eSR was preserved and remained robust throughout tumor dissection, indicating an intact cochlear nerve. Four weeks postoperatively, the patient exhibited open-set speech capacity (14% CNC and 36% AzBio in quiet).The current study demonstrates the feasibility of using intraoperative eSR via a CI electrode to monitor cochlear nerve integrity during VS resection, which may indicate successful CI outcomes. These preliminary findings require further substantiation in a larger study.

Compare speech perception performance growth and benchmark score achievement among adult cochlear implant (CI) recipients with single-sided deafness (SSD) versus bilateral moderate to profound hearing loss.Retrospective matched cohort analysis.Tertiary referral center.Adults with SSD or bilateral moderate to profound hearing sensorineural hearing loss who underwent cochlear implantation from 2014 to 2019.Cochlear implantation.Time-to-benchmark speech perception score (CNC, AzBio in quiet) and speech performance within first postoperative year.Thirty-three SSD patients were matched to 66 bilateral hearing loss patients (referent cohort) for duration of deafness and preoperative ipsilateral CNC scores. Although SSD patients were more likely to achieve benchmark CNC scores more quickly compared with matched referents, this difference did not reach statistical significance (HR 1.72; 95% CI 0.78-3.82; p = 0.18). AzBio scores showed similar trends (HR 1.40; 95% CI 0.66-2.98; p = 0.38). At last follow-up, the SSD cohort had lower CNC (median 54% vs. 62%; p = 0.019) and AzBio scores (median 72% vs. 84%; p = 0.029) compared to the referent cohort.No significant difference in speech perception performance growth (i.e., time-to-benchmark speech perception score) was identified between SSD and bilateral hearing loss CI recipients, although patients with bilateral hearing loss achieved higher scores in the implanted ear within the first year of follow-up.

To determine the relationship between intraoperative electrocochleography (ECochG) measurements and residual hearing preservation after cochlear implant (CI) surgery by comparing differences between preoperative and immediate postoperative bone conduction thresholds.Prospective cohort study.Tertiary academic referral center.Sixteen patients with preoperative residual hearing and measurable (no-vibrotactile) bone conduction thresholds at 250 and/or 500 Hz who underwent cochlear implantation.Intraoperative ECochG and air and bone conduction thresholds.Nine patients showed no significant drop (30%) in ECochG amplitude during CI surgery with an average preoperative and immediate postoperative BC threshold of 46 and 39 dB HL, respectively, at 500 Hz. Seven patients with a decrease in ECochG amplitude of 30% or greater showed an average preoperative 500 Hz BC threshold of 32 dB HL and immediate postoperative threshold of 55 dB HL. Air and bone conduction thresholds measured approximately 1 month after CI surgery show delayed-onset of hearing loss across our study patients.A small decrease (30%) in difference response or cochlear microphonics amplitude correlates with no significant changes in immediate postoperative residual hearing, whereas patients who show larger changes (≥30%) in difference response or cochlear microphonics amplitude during intraoperative ECochG measurements show significant deterioration in BC thresholds. This study reveals the necessity of prompt postoperative bone conduction measurement to isolate the intraoperative cochlear trauma that may be detected during intraoperative ECochG measurements. Although delayed postoperative audiometrics represent longer-term functional hearing, it includes the sum of all postoperative changes during the recovery period, including subacute changes after implantation that may occur days or weeks later. Measuring air and bone conduction thresholds immediately postoperatively will better isolate factors influencing intraoperative, early postoperative, and delayed postoperative hearing loss. This will ultimately help refine surgical technique, device design, and highlight the use of intraoperative ECochG in monitoring cochlear trauma during CI surgery.

OBJECTIVE This study aims to determine if early device activation can influence cochlear implant electrode impedances by providing electrical stimulation within hours after cochlear implant surgery. DESIGN Electrode impedances were measured intraoperatively, at device activation, and one-month after device activation in three groups: users whose devices were activated (1) on the same day (Same Day), (2) the next day (Next Day), and (3) 10-14 days (Standard), after cochlear implant surgery. STUDY SAMPLE Electrode impedances are reported in fifty-one patients implanted with a Cochlear™ Nucleus® Cochlear Implant. RESULTS Compared to intraoperative levels, impedances dropped within hours for the Same Day activation group (p

Electrocochleography (ECochG) is an electrophysiological technique that records electrical potentials generated by different components of the inner ear and peripheral cochlear nerve in response to acoustic stimulation. ECochG responses can be analyzed into (1) cochlear microphonics (CM), (2) auditory nerve neurophonics, (3) summating potential, and (4) compound action potential. Over the past few decades, there have been ongoing refinements in technique and updates in the understanding of recorded potentials. Historically, ECochG found its main application in the diagnostic evaluation of Meniere’s disease (MD). However, in the last decade, the focus has shifted towards cochlear implantation (CI). In patients with residual hearing after CI, combined electric and acoustic stimulation has resulted in improved hearing and speech outcomes. Despite efforts to mitigate trauma during electrode insertion, hearing preservation rates vary after surgery. During implantation, real-time ECochG offers an opportunity to measure frequency specific CMs elicited from a localized region in the cochlea as the surgeon inserts the electrode array. In extracochlear ECochG recordings, the recording electrode can be placed on the promontory, the stapes, or the tympanic membrane. Intracochlear ECochG can be performed by inserting a recording electrode into the cochlea or by using one of the CI electrodes as the recording electrode. The loss of intraoperative ECochG signal may indicate cochlear trauma from electrode insertion, but the association between intraoperative ECochG changes and cochlear trauma remains controversial. The ability to monitor cochlear trauma during CI electrode placement holds promise to improve hearing preservation outcomes, modify surgical techniques, and change electrode design. The goal of this review is to provide a comprehensive overview of the electrophysiology and history of ECochG, discuss its recent applications in CI, and explore the ongoing research in this expanding field.

OBJECTIVE Facial nerve function, hearing preservation, and tumor control have been the primary benchmarks used to assess vestibular schwannoma (VS) outcomes. Acknowledging the frequent discrepancy between what physicians prioritize and what patients value, there has been increasing prioritization of patient-reported outcome measures when evaluating the impact of VS diagnosis and its treatment. Motivated by reported limitations of prior instruments used to assess quality of life (QOL) in patients with VS, the authors describe the development and validation of a new disease-specific QOL measure: the Vestibular Schwannoma Quality of Life (VSQOL) Index. METHODS The content development phase comprised identification of clinically important domains and prioritization of feelings or concerns individuals with VS may have. The validation phase encompassed determining how items were grouped into domains and eliminating redundant items. Both phases leveraged data from cross-sectional and longitudinal surveys, expertise from a multidisciplinary working group, and patients with a broad range of experiences with VS (n = 42 during content development and n = 263 during validation). Domain scores from the new instrument were assessed for reliability and correlation with other measures of similar constructs. RESULTS The VSQOL Index consists of 40 items that evaluate the impact of VS diagnosis and its management on QOL, treatment satisfaction, and employment and is estimated to take 8–10 minutes to complete. Domain scores range from 0 (worst) to 100 (best) and demonstrate excellent psychometric properties, including content, construct, and convergent validity and both internal consistency (Cronbach’s alphas 0.83 to 0.91) and test-retest reliability (reliability coefficients 0.86 to 0.96). CONCLUSIONS The VSQOL Index is a valid and reliable measure that overcomes several limitations of prior instruments, including omission or underrepresentation of domains that frequently impact well-being, such as pain, cognition, satisfaction or regret surrounding treatment decisions, and occupational limitations, to comprehensively evaluate the impact of VS diagnosis or its treatment on QOL.

Introduction: When mapping cochlear implant (CI) patients with limited reporting abilities, the lowest electrical stimulus level that produces a stapedial reflex (i.e., the electrical stapedius reflex threshold [eSRT]) can be measured to estimate the upper bound of stimulation on individual or a subset of CI electrodes. However, eSRTs measured for individual electrodes or a subset of electrodes cannot be used to predict the global adjustment of electrical stimulation levels needed to achieve comfortable loudness sensations that can be readily used in a speech coding strategy. In the present study, eSRTs were measured for 1-, 4-, and 15-electrode stimulation to (1) determine changes in eSRT levels as a function of the electrode stimulation mode and (2) determine which stimulation mode eSRT levels best approximate comfortable loudness levels from patients’ clinical maps. Methods: eSRTs were measured with the 3 different electrical stimulation configurations in 9 CI patients and compared with behaviorally measured, comfortable loudness levels or M-levels from patients’ clinical maps. Results: A linear, mixed-effects, repeated-measures analysis revealed significant differences (p < 0.01) between eSRTs measured as a function of the stimulation mode. No significant differences (p = 0.059) were measured between 15-electrode eSRTs and M-levels from patients’ clinical maps. The eSRTs measured for 1- and 4-electrode stimulation differed significantly (p < 0.05) from the M-levels on the corresponding electrodes from the patients’ clinical map. Conclusion: eSRT profiles based on 1- or 4-electrode stimulation can be used to determine comfortable loudness level on either individual or a subset of electrodes, and 15-electrode eSRT profiles can be used to determine the upper bound of electrical stimulation that can be used in a speech coding strategy.

Objective To raise awareness of a unique complication associated with continuous positive airway pressure (CPAP) use after cochlear implantation to improve early detection, prevent unnecessary testing, and facilitate treatment. Study design Case series. Setting Tertiary referral center. Subjects Patients who developed subcutaneous air around the receiver-stimulator device and the associated ground electrode in the setting of CPAP usage, which resulted in open-circuit electrode failures. Main outcome measures Clinical course and intervention. Results Two patients were identified that fit this criterion. Both patients were noted to have poor implant performance secondary to high or open impedances and concomitant emphysema surrounding the cochlear implant receiver-stimulator. Manual massage offered transient improvement, but programming changes ultimately led to improved sound quality and resolution of impedance anomalies in both cases. Conclusions Subcutaneous air collection surrounding the cochlear implant receiver-stimulator in the setting of CPAP use is an uncommon but clinically relevant complication that can be recognized by characteristic physical examination findings and impedance changes. Early and accurate recognition of this event can prevent unnecessary testing and facilitate early effective treatment.

Electrode impedances play a critical role in cochlear implant programming. It has been previously shown that impedances rise during periods of non-use, such as the post-operative recovery period. Then when the device is activated and use is initiated, impedances fall and are typically stable. In this study, we report a new pattern where electrode impedances increase with device use and decrease with device rest.Electrode impedances were measured three to four times every day over a span of 1-3 months for two cochlear implant patients.Two patients with a Nucleus cochlear implant participated in this study.Both subjects in this study show wide fluctuations in electrode impedances. By taking serial electrode impedance measurements throughout a day of use, we observe that electrode impedances consistently increase with device use and decrease with device rest.In this study, we report two cases of electrode impedances increasing as a function of device use. Numerous management strategies were employed to reduce this effect but none prevailed; a clear pathophysiologic mechanism remains elusive. Further study into the cause of this electrode impedance pattern is warranted to establish a management strategy for these cochlear implant users.

OBJECTIVES In adult cochlear implant patients, conventional audiometry is used to measure postoperative residual hearing which requires active listening and patient feedback. However, audiological measurements in pediatric cochlear implant patients are both challenging as well as time consuming. Intracochlear electrocochleography (ECOG) offers an objective and a time-efficient method to measure frequency-specific cochlear microphonic or difference thresholds (CM/DIF) thresholds that closely approximate auditory thresholds in adult cochlear implant patients. The correlation between CM/DIF and behavioral thresholds has not been established in pediatric cochlear implant patients. In the present study, CM/DIF thresholds were compared with audiometric thresholds in pediatric cochlear implant patients with postoperative residual hearing. DESIGN Thirteen (11 unilateral and 2 bilateral) pediatric cochlear implant patients (mean age = 9.2 years ± 5.1) participated in this study. Audiometric thresholds were estimated using conventional, condition play, or visual reinforcement audiometry. A warble tone stimulus was used to measure audiometric thresholds at 125, 250, 500, 1000, and 2000 Hz. ECOG waveforms were elicited using 50-msec acoustic tone-bursts. The most apical intracochlear electrode was used as the recording electrode with an extra-cochlear ground electrode. The ECOG waveforms were analyzed to determine CM/DIF thresholds that were compared with pediatric cochlear implant patients' audiometric thresholds. RESULTS The results show a significant correlation (r = 0.77, p < 0.01) between audiometric and CM/DIF thresholds over a frequency range of 125 to 2000 Hz in pediatric cochlear implant patients. Frequency-specific comparisons revealed a correlation of 0.82, 0.74, 0.69, 0.41, and 0.32 between the audiometric thresholds and CM/DIF thresholds measured at 125, 250, 500, 1000, and 2000 Hz, respectively. An average difference of 0.4 dB (±14 dB) was measured between the audiometric and CM/DIF thresholds. CONCLUSIONS Intracochlear ECOG can be used to measure CM/DIF thresholds in pediatric cochlear implant patients with residual hearing in the implanted ear. The CM/DIF thresholds are similar to the audiometric thresholds at lower test frequencies and offer an objective method to monitor residual hearing in difficult-to-test pediatric cochlear implant patients.

Objective Intraoperative far-field auditory brainstem response (ABR) and direct cochlear nerve action potential monitoring using neural response imaging (NRI) are techniques for monitoring the cochlear nerve during vestibular schwannoma (VS) surgery. A new paradigm has developed where the cochlear nerve is anatomically preserved during tumor removal to facilitate cochlear implantation in select circumstances. This report describes the use of an unmodified commercial cochlear implant (CI) to elicit electrically-evoked direct cochlear nerve and far-field ABR monitoring to evaluate the status of the cochlear nerve during tumor resection in real time. Patients Adult female with unilateral, sporadic VS. Intervention(s) Cochlear implantation followed by translabyrinthine resection of VS in single operation. Main outcome measures During tumor resection intra-cochlear electrodes were used to deliver electrical stimulation and measure NRI or the cochlear nerve action potential. Electrically-evoked ABR (eABR) was measured using surface electrodes and wave V was monitored (far-field ABR) during surgery. Results A 61-year-old female was evaluated for a unilateral, enlarging intracanalicular VS with asymmetric SNHL. The patient opted for microsurgery and due to her bilateral hearing loss was a candidate for CI. Cochlear implantation with an unmodified, commercially available lateral wall electrode was performed. The remainder of the approach and tumor resection was performed under continuous eABR and NRI monitoring. Gross total resection was achieved with intact eABR and NRI at the conclusion of the case. Changes in ABR and NRI consistently recovered after modifying dissection strategy. The patient reported auditory percepts with her cochlear implant postoperatively. Conclusions This report demonstrates the feasibility of using real-time NRI and eABR with a CI to facilitate preservation of the cochlear nerve during VS microsurgery. Using this method to mitigate cochlear nerve trauma during microsurgery may preserve the option of CI for hearing rehabilitation.

To determine if temporoparietal scalp thickness assessed via preoperative imaging predicts retention events in patients who have cochlear implants with diametric magnets and various sound processor types.Retrospective chart and radiological review.Tertiary referral center.One hundred forty-three adult patients who have cochlear implants with diametric magnets.Skin flap thickness, retention events, body mass index (BMI), and magnet strength.Of 42 patients with the most recent generation off-the-ear sound processor (OTE2), 13 (31.0%) had retention events. Of patients with a temporoparietal scalp thickness less than 8 mm, all patients could ultimately retain the device, though one of 26 was noted to have tenuous retention. Of patients with 8 to 10 mm skin flaps, 3 of 6 (50%) could not retain the device, and with more than 10 mm skin flaps, 7 of 10 (70%) could not retain the device. In the more than 10 mm group, two additional patients could not either retain the device at initial activation or were noted to have tenuous retention. Of 124 patients with behind-the-ear (BTE) sound processors, only 2 (1.6%) could not retain the device at initial activation, and 3 (2.4%) exhibited tenuous retention after 3 months of device use. Results from the first generation off-the-ear sound processor (OTE1) are also reported.Temporoparietal scalp thickness measured by preoperative imaging is associated with processor retention for patients with the OTE2 sound processor and diametric magnets. All patients with less than 8 mm scalp thickness could retain the OTE2, while 50% of patients with 8 to 10 mm scalp thickness and 70% with more than 10 mm scalp thickness could not retain the device. Patients should be counseled regarding their sound processor choice and/or considered candidates for skin flap reduction or other intervention as indicated. Retention events with BTE processors are rare.

Electrode impedances play an important role in cochlear implant patient management. During clinical visits, electrode impedances are calculated from a single point voltage waveform. In the present study, multipoint electrode impedance analysis was performed to study electrode impedance and its subcomponents in patients with three different types of cochlear implant electrode arrays.Voltage waveforms were measured at six different time points during the cathodic phase of a biphasic pulse in forty-seven cochlear implant patients with perimodiolar, mid-scala, or lateral wall electrode arrays. Multipoint electrode impedances were used to determine access resistance and polarization impedance.Access resistance of approximately 5 kΩ was calculated across the three different electrode arrays. Mid-scala electrodes showed a smaller increase in impedances as a function of pulse duration compared to the other electrodes. Patients with lower impedances showed higher capacitance and lower resistance, suggesting that differences in electrochemical reaction at the electrodes' surface can influence impedances in cochlear implants.Analysis of cochlear implant electrode impedances and their subcomponents provides valuable information about resistance to the flow of current between stimulating and return electrodes, and build an understanding of the contribution of electrochemical processes used to deliver electrical stimulation to the auditory nerve.

To evaluate the impact of prolonged auditory deprivation on speech perception outcomes in adult acquired single-sided deafness (SSD) cochlear implant (CI) recipients.Retrospective case series.Tertiary care academic center.Acquired SSD in adults with and without prolonged duration of deafness (defined as10 yr) who underwent CI between 2014 and 2019.CI.Consonant-nucleus-consonant (CNC) and AzBio in quiet scores within first year of follow-up.A total of 35 adult patients with SSD were evaluated, with a median overall duration of deafness of 2.4 years (interquartile range [IQR] 1.2-6.0 yr): seven patients with prolonged auditory deprivation (median 18 yr, IQR 15-28) were compared with 28 SSD patients with duration of deafness less than 10 years (median 1.7 yr, IQR 1.1-3.2). At last follow-up, the median CNC scores were 39% (IQR 31-64) and 54% (IQR 46-64) for the prolonged and shorter duration of deafness cohorts, respectively (p = 0.3). The median AzBio scores were 66% (IQR 65-68) and 72% (IQR 60-82) for the prolonged and shorter duration of deafness cohorts, respectively (p = 0.6). In a separate analysis evaluating duration of deafness as a continuous variable across all 35 patients, Spearman correlation coefficients for associations of duration of deafness with most recent CNC and AzBio scores were -0.02 (p = 0.9) and 0.02 (p = 0.9), respectively.Adult CI recipients with acquired SSD, with and without prolonged auditory deprivation, demonstrated comparable speech perception scores. Prolonged duration of deafness alone should not preclude a motivated SSD patient from undergoing cochlear implantation.

To raise awareness of a unique complication associated with continuous positive airway pressure (CPAP) use after cochlear implantation to improve early detection, prevent unnecessary testing, and facilitate treatment.Case series.Tertiary referral center.Patients who developed subcutaneous air around the receiver-stimulator device and the associated ground electrode in the setting of CPAP usage, which resulted in open-circuit electrode failures.Clinical course and intervention.Two patients were identified that fit this criterion. Both patients were noted to have poor implant performance secondary to high or open impedances and concomitant emphysema surrounding the cochlear implant receiver-stimulator. Manual massage offered transient improvement, but programming changes ultimately led to improved sound quality and resolution of impedance anomalies in both cases.Subcutaneous air collection surrounding the cochlear implant receiver-stimulator in the setting of CPAP use is an uncommon but clinically relevant complication that can be recognized by characteristic physical examination findings and impedance changes. Early and accurate recognition of this event can prevent unnecessary testing and facilitate early effective treatment.

OBJECTIVE To evaluate the utility of intraoperative electrocochleography (ECochG) as a predictive tool for preservation of residual acoustic hearing after cochlear implantation. DATA SOURCES A systematic review employing a multi-database search strategy (Ovid MEDLINE, Embase, EBM Cochrane, and Scopus) was conducted from inception to August 1, 2019. English language studies in humans were included. STUDY SELECTION All articles were independently reviewed by two authors according to Preferred Reporting Items of Systematic Reviews and Meta-analysis (PRISMA) guidelines. Studies without intraoperative ECochG obtained during cochlear implantation were excluded. DATA EXTRACTION Extracted variables included number of patients, ECochG recording technique, success rate of obtaining ECochG potentials, intraoperative changes in ECochG signal, and postoperative hearing preservation outcomes. DATA SYNTHESIS Among 537 eligible articles, 22 met inclusion criteria encompassing 498 unique patients. Ten studies featured extracochlear measurements, eight featured intracochlear measurements, and four featured both. Extracochlear ECochG had an average (SD) recording success rate of 94.9% (12.7%) while intracochlear ECochG had an average (SD) recording success rate of 91.8% (9.8%). One hundred forty five unique patients from six studies had complete intraoperative ECochG data with postoperative behavioral audiometry. After accounting for study-specific definitions of ECochG signal disturbance, worsening changes in intraoperative ECochG signal predicted postoperative hearing loss with limited sensitivity and specificity and notable heterogeneity across studies. CONCLUSIONS Intraoperative ECochG recordings can be obtained in over 90% of patients, but accuracy in predicting postoperative hearing loss remains limited. Standardization of intraoperative ECochG monitoring technique and data interpretation are necessary to more robustly investigate outcomes and refine technique.

OBJECTIVE. To determine if wideband tympanometry (WBT) can differentiate types of middle ear effusion (MEE): serous, mucoid, and purulent. STUDY DESIGN. Prospective cohort study. SETTING. Tertiary care children’s hospital. METHODS. Children who met American Academy of Otolaryngology–Head and Neck Surgery’s guidelines for ventilation tube insertion had WBT after anesthesia induction but before tympanotomy. MEE was categorized into 1 of 4 comparison groups: serous effusion, mucoid effusion, purulent effusion, or no effusion. WBT measurements were averaged to 16 one-third octave frequency bands, and comparison of the absorbance patterns for each MEE type was performed through a linear mixed effects model. RESULTS. A total of 118 children (211 ears) were included: 47 females (39.8%) and 71 males (60.2%). The mean age was 2.73 years (95% CI, 2.25-3.22); mean weight, 14.35 kg (95% CI, 12.85-15.85); and mean Z score, 1.13 (95% CI, −0.64 to 2.33). Effusions included 61 mucoid (28.9%), 30 purulent (14.2%), and 14 serous (6.6%), with 106 (50.2%) having no effusion. No significant differences were found for sex, race, age, weight, or Z score among the 4 types of effusion (P < .05). WBT showed a significant difference in median absorption among the effusion groups (P < .001), with a medium effect size of 0.35. CONCLUSIONS. WBT has potential use to differentiate types of MEE and should be studied further as a tool for investigating how the natural history and management of serous and mucoid effusions may differ.

In cochlear implants, the maximum current I (Amperes) that can be delivered on a cochlear implant electrode is determined by V = I * R, where V = compliance voltage (Volts) and R = electrode impedance (Ohms). Generally, electrode impedances are measured during each clinical visit and are used to set electrical stimulation parameters in cochlear implants. However, electrode impedances can rise during the course of cochlear implant use and lead to electrical stimulation voltage requirements exceeding the maximum compliance voltage of the medical device. Electric stimulation requirements that exceed the compliance voltage lead to clipping of the biphasic electrical pulse (current going into the cochlea) and are known to adversely affect cochlear implant outcomes.Thirteen (11 unilateral and 2 bilateral) Advanced Bionics cochlear implant patients with a HiRes 90k™ cochlear implant participated in this study. Speech perception scores were measured using the patient's baseline clinical program with the most comfortable loudness levels (M-levels) and the following four test programs: (1) stimulation clipped at 15% below clinical M-levels (15%C) (2) stimulation clipped at 30% below clinical M-levels (30%C) (3) M-levels decreased by 15% (15%M) and (4) M-levels decreased by 30% (30%C). Speech perception scores were measured using AzBio sentences presented at 60 dB SPL in quiet and in the presence of multi-talker babble (+10 dB SNR).Relative to the clinical baseline program, speech perception scores with the four test programs decreased in both quiet and noisy listening conditions. In quiet, speech perception scores measured with the 30%M and 30%C programs were significantly (p0.001) poorer than the baseline program. No significant differences in speech perception scores were measured between the baseline and the 15%C or 15%M programs. In the noisy listening condition, speech perception scores were significantly poorer than the baseline program for the 15%C (p = 0.008), 30%C (p0.001), and 30%M (p0.001) programs. No significant differences in speech perception scores were obtained between the baseline and the 15%M program in the noisy listening condition. Speech perception scores measured with the 30%C program were significantly (p0.001) poorer than those with the 30%M program, suggesting that clipping was more detrimental than reducing electrical stimulation levels.Small amounts (15%) of clipping can significantly decrease speech perception in the presence of background noise. Large amounts (30%) of both clipping and M-level reduction may lead to significantly poorer speech perception in quiet and in background noise. The decrease in speech perception scores can most likely be attributed to reduced volume and poorer spectro-temporal representation. Therefore, it is important to establish comfortably loud electrical stimulation levels without exceeding the compliance voltage to maximize cochlear implant outcomes.

OBJECTIVE Determine if changes in middle ear absorbance measured with wide-band tympanometry (WBT) occur following hearing-preservation cochlear implantation (CI). Such measures may provide insight into the mechanisms of acoustic hearing loss postimplantation. STUDY DESIGN Clinical capsule report. SETTING Tertiary academic referral center. DESIGN WBT absorbance was measured bilaterally during pre- and postoperative clinical office visits in five unilaterally-implanted cochlear implant recipients. Pre- and postoperative WBT measures were compared within each subject in the implanted and contralateral, unimplanted ears. RESULTS In general, WBT absorbance measurements show a broad spectral pattern including two or three distinct peaks measured over a frequency range of 226 to 8000 Hz. Grand average and linear mixed model comparisons between the pre- and postoperative WBT patterns show significantly reduced (p

Objectives To determine whether electrocochleography (ECoG) thresholds, especially cochlear microphonic and auditory nerve neurophonic thresholds, measured using an intracochlear electrode, can be used to predict pure-tone audiometric thresholds following cochlear implantation in ears with residual hearing. Design Pure-tone audiometric thresholds and ECoG waveforms were measured at test frequencies from 125 to 4000 Hz in 21 Advanced Bionics cochlear implant recipients with residual hearing in the implanted ear. The "difference" and "summation" responses were computed from the ECoG waveforms measured from two alternating phases of stimulation. The interpretation is that difference responses are largely from the cochlear microphonic while summating responses are largely from the auditory nerve neurophonic. The pure-tone audiometric thresholds were also measured with same equipment used for ECoG measurements. Results Difference responses were observed in all 21 implanted ears, whereas summation response waveforms were observed in only 18 ears. The ECoG thresholds strongly correlated (r = 0.87, n = 150 for difference response; r = 0.82, n = 72 for summation response) with audiometric thresholds. The mean difference between the difference response and audiometric thresholds was -3.2 (±9.0) dB, while the mean difference between summation response and audiometric thresholds was -14 (±11) dB. In four out of 37 measurements, difference responses were measured to frequencies where no behavioral thresholds were present. Conclusions ECoG thresholds may provide a useful metric for the assessment of residual hearing in cochlear implant subjects for whom it is not possible to perform behavioral audiometric testing.

Objectives The upper loudness limit of electrical stimulation in cochlear implant patients is sometimes set using electrically elicited stapedius reflex thresholds (eSRTs), especially in children for whom reporting skills may be limited. In unilateral cochlear implant patients, eSRT levels are measured typically in the contralateral unimplanted ear because the ability to measure eSRTs in the implanted ear is likely to be limited due to the cochlear implant surgery and consequential changes in middle ear dynamics. This practice is particularly limiting in the case of fitting bilaterally implanted pediatric cases because there is no unimplanted ear option to choose for eSRT measurement. The goal of this study was to identify an improved measurement protocol to increase the success of eSRT measurement in ipsilateral or contralateral or both implanted ears of pediatric cochlear implant recipients. This work hypothesizes that use of a higher probe frequency (e.g., 1000 Hz compared with the 226 Hz standard), which is closer to the mechanical middle ear resonant frequency, may be more effective in measuring middle ear muscle contraction in either ear. Design In the present study, eSRTs were measured using multiple probe frequencies (226, 678, and 1000 Hz) in the ipsilateral and contralateral ears of 19 children with unilateral Advanced Bionics (AB) cochlear implants (mean age = 8.6 years, SD = 2.29). An integrated middle ear analyzer designed by AB was used to elicit and detect stapedius reflexes and assign eSRT levels. In the integrated middle ear analyzer system, an Interacoustics Titan middle ear analyzer was used to perform middle ear measurements in synchrony with research software running on an AB Neptune speech processor, which controlled the delivery of electrical pulse trains at varying levels to the test subject. Changes in middle ear acoustic admittance following an electrical pulse train stimulus indicated the occurrence of an electrically elicited stapedius reflex. Results Of the 19 ears tested, ipsilateral eSRTs were successfully measured in 3 (16%), 4 (21%), and 7 (37%) ears using probe tones of 226, 678, and 1000 Hz, respectively. Contralateral eSRT levels were measured in 11 (58%), 13 (68%), and 13 (68%) ears using the three different probe frequencies, respectively. A significant difference was found in the incidence of successful eSRT measurement as a function of probe frequency in the ipsilateral ears with the greatest pair-wise difference between the 226 and 1000 Hz probe. A significant increase in contralateral eSRT measurement success as a function of probe frequency was not found. These findings are consistent with the idea that changes in middle ear mechanics, secondary to cochlear implant surgery, may interfere with the detection of stapedius muscle contraction in the ipsilateral middle ear. The best logistic, mixed-effects model of the occurrence of successful eSRT measures included ear of measurement and probe frequency as significant fixed effects. No significant differences in average eSRT levels were observed across ipsilateral and contralateral measurements or as a function of probe frequency. Conclusion Typically, measurement of stapedius reflexes is less successful in the implanted ears of cochlear implant recipients compared with measurements in the contralateral, unimplanted ear. The ability to measure eSRT levels ipsilaterally can be improved by using a higher probe frequency.

Although cochlear implants (CI) traditionally have been used to treat individuals with bilateral profound sensorineural hearing loss, a recent trend is to implant individuals with residual low-frequency hearing. Notably, many of these individuals demonstrate an air-bone gap (ABG) in low-frequency, pure-tone thresholds following implantation. An ABG is the difference between audiometric thresholds measured using air conduction (AC) and bone conduction (BC) stimulation. Although behavioralbehavioral AC thresholds are straightforward to assess, BC thresholds can be difficult to measure in individuals with severe-to-profound hearing loss because of vibrotactile responses to high-level, low-frequency stimulation and the potential contribution of hearing in the contralateral ear. Because of these technical barriers to measuring behavioral BC thresholds in implanted patients with residual hearing, it would be helpful to have an objective method for determining ABG. This study evaluated an innovative technique for measuring electrocochleographic (ECoG) responsesusing the cochlear microphonic (CM) response to assess AC and BC thresholds in implanted patients with residual hearing. Results showed high correlations between CM thresholds and behavioral audiograms for AC and BC conditions, thereby demonstrating the feasibility of using ECoG as an objective tool for quantifying ABG in CI recipients.

Objective To demonstrate benefits for speech perception and everyday listening in quiet and in noise with a speech-enhancement strategy called ClearVoice, which was designed to improve listening in complex acoustic environments without compromising hearing in quiet. Study design A 2-week randomized crossover design was used to evaluate ClearVoice in 46 adults unilaterally implanted with a CII/HiRes 90K cochlear implant who had at least 6 months experience with HiRes Fidelity 120 sound processing. Speech perception was assessed using the AzBio sentences presented in quiet, in speech-spectrum noise and in multitalker babble. Subjective listening benefit and strategy preference were assessed with a questionnaire. ClearVoice has 3 gain settings (low, medium, and high), each intended as a full-time listening option according to individual preference. Speech understanding after acute use of ClearVoice-low was compared with HiRes Fidelity 120 during an initial test session. Speech perception abilities were compared with HiRes Fidelity 120 after 2 weeks of exclusive use of ClearVoice-medium, and after 2 weeks of exclusive use of ClearVoice-high. During a fifth week, participants were fit with 3 programs for comparison (HiRes Fidelity 120, ClearVoice-medium, and ClearVoice-high), after which, they reported preference and everyday listening benefits via a questionnaire. Results ClearVoice significantly improved speech understanding in speech-spectrum noise and multitalker babble, did not compromise listening in quiet, was preferred for everyday listening, and provided improved hearing in real-life situations. Conclusion ClearVoice improves hearing in noise for cochlear implant recipients who use HiRes Fidelity 120 sound processing.

Objectives—Patients with a cochlear implant (CI) in one ear and a hearing aid in the other ear commonly achieve the highest speech understanding scores when they have access to both electrically and acoustically stimulated information (EAS). At issue in this study was whether a measure of auditory function in the hearing-aided ear would predict the benefit to speech understanding when the information from the aided ear was added to the information from the CI. Design—The subjects were 22 bimodal listeners with a CI in one ear and low-frequency acoustic hearing in the non-implanted ear. The subjects were divided into two groups -- one with mild to moderate low-frequency loss and one with severe to profound loss. Measures of auditory function included (i) audiometric thresholds at ≤ 750 Hz, (ii) speech understanding scores (words in quiet and sentences in noise), and (iii) spectral modulation detection (SMD) thresholds. In the SMD task, one stimulus was a flat spectrum noise and the other was a noise with sinusoidal modulations at 1.0 peak/octave. Results—Significant correlations were found among all three measures of auditory function and the benefit to speech understanding when the acoustic and electric stimulation were combined. Benefit was significantly correlated with audiometric thresholds (r = −0.814), acoustic speech understanding (r = 0.635), and SMD thresholds (r = −0.895) in the hearing-aided ear. However, only the SMD threshold was significantly correlated with benefit within the group with mildmoderate loss (r = −0.828) and within the group with severe-profound loss (r = −0.896). Conclusions—The SMD threshold at 1 cycle/octave has the potential to provide clinicians with information relevant to the question of whether an ear with low-frequency hearing is likely to add to the intelligibility of speech provided by a CI.

Sound coding strategies for Cochlear Implant (CI) listeners can be used to control the trade-off between speech performance and power consumption. Most commercial CI strategies use non-simultaneous channel stimulation, stimulating only one electrode at a time. One could add parallel simultaneous stimulating channels such that the electrical interaction between channels is increased. This would produce spectral smearing, because the electrical fields of the simultaneous stimulated channels interact, but also power savings. The parallel channels produce a louder sensation than sequential stimulation. To test this hypothesis we implemented different sound coding strategies using a research interface from Advanced Bionics: the commercial F120 strategy using sequential channel stimulation (one channel equals two electrodes with current steering) and the Paired strategy, consisting of simultaneous stimulation with two channels. Here, the electrical field of both channels will interact, requiring less current on each channel to perceive the same loudness as with F120. However, channel interaction between the independent channels may reduce speech recognition or understanding. This can be diminished by adding an inverse-polarity stimulation channel between both channels. This strategy is termed Paired with Flanks. Additionally, Triplet with three channels and an adjacent Flank style was investigated. For each strategy we measured speech intelligibility with the Hochmair-Schulz-Moser sentence test. Spectral resolution was assessed using a spectral modulation depth detection task. Results show that Paired without Flanks obtains similar performance while reducing the current by 20% on average compared to F120. Triplet with and without Flanks shows overall poorer performance when compared to F120. All strategies inhibit the option to increase the pulse width which would result in even further decreased power consumption.

Objective: Both simultaneous (SI) and sequential stimulation of intra-cochlear electrodes can be used to generate pitches that are intermediate to the physical electrodes (PEs). The goal of this study was to compare the spread of neural excitation for SI and sequential dual-electrode stimulation with the spread of neural excitation for the intermediate electrode using electrically evoked compound action potentials. Design: Seven Advanced Bionics cochlear implant users with either CII or HiRes 90k implant and HiFocus 1 or HiFocus 1j electrode array participated in this study. A masker-probe subtraction method was used to derive neural excitation patterns for SI nonadjacent dual-electrode stimulation, apical and basal-first sequential nonadjacent dual-electrode stimulation, and the intermediate PE. For apical-first sequential (SE a ) stimulation, the masker pulse on the apical electrode immediately preceded the masker pulse on the basal electrode, and vice versa for basal-first sequential stimulation (SE b ). The electrodes used for dual-electrode stimulation were separated by an intermediate PE, which represents a spatial distance of approximately 2 mm. Current levels necessary to achieve comfortable loudness were determined for each masker and probe stimulus. During the evoked compound action potential measurements, the masker was fixed in location, whereas the probe was varied across a subset of electrodes in the array. Neural responses were calculated by subtracting the response to the probe from the masked response. Results: Neural excitation patterns were normalized to their peak and analyzed in terms of their area and center of gravity. The area and center of gravity for SI nonadjacent dual-electrode stimulation were similar to those of the intermediate PE. In contrast, the area for the two modes of sequential nonadjacent dual-electrode (SE a and SE b ) stimulation differed significantly from the intermediate PE. The center of gravity for SE a stimulation also differed significantly from the intermediate PE, whereas there was no significant difference in the center of gravity between SE b stimulation and the intermediate PE. Conclusions: Peripheral neural activation patterns suggest a similar spread of excitation for SI dual-electrode stimulation and the intermediate PE. The spread of excitation associated with sequential dual-electrode stimulation is generally different from the intermediate PE, and it varies depending on the order of the sequential pulses.

Spectral resolution has been reported to be closely related to vowel and consonant recognition in cochlear implant (CI) listeners. One measure of spectral resolution is spectral modulation threshold (SMT), which is defined as the smallest detectable spectral contrast in the spectral ripple stimulus. SMT may be determined by the activation pattern associated with electrical stimulation. In the present study, broad activation patterns were simulated using a multi-band vocoder to determine if similar impairments in speech understanding scores could be produced in normal-hearing listeners. Tokens were first decomposed into 15 logarithmically spaced bands and then re-synthesized by multiplying the envelope of each band by matched filtered noise. Various amounts of current spread were simulated by adjusting the drop-off of the noise spectrum away from the peak (40-5 dBoctave). The average SMT (0.25 and 0.5 cyclesoctave) increased from 6.3 to 22.5 dB, while average vowel identification scores dropped from 86% to 19% and consonant identification scores dropped from 93% to 59%. In each condition, the impairments in speech understanding were generally similar to those found in CI listeners with similar SMTs, suggesting that variability in spread of neural activation largely accounts for the variability in speech perception of CI listeners.

The ability to detect sinusoidal spectral envelope from an unmodulated (flat) spectrum has shown a strong correlation with speech perception in quiet and noisy listening conditions in normal hearing, hearing-impaired, and cochlear implant users. In this study, the mismatch negativity (MMN) was collected from 10 normal-hearing adult listeners and used to determine if modulation detection thresholds derived electrophysiologically correlate with the psychophysically measured spectral modulation detection thresholds. MMNs were present for most participants with spectral contrasts of 10 and 20 dB, suggesting that the MMN may be a promising neurophysiologic measure of spectral envelope perception when nonbehavioral measures are desired.

(2010). SPAN: Improved Current Steering on the Advanced Bionics CII and HiRes90K System. Cochlear Implants International: Vol. 11, Proceedings of the 9th European Symposium on Paediatric Cochlear Implantation, Warsaw, 2009, pp. 465-468.

thresholds observed at 0.25 and 0.50 peaks/octave (Saoji et al., 2009). The bandwidth and audio-frequency range of the noise band carrier has little effect on SMD thresholds of NH listeners. That is, sensitivity to 1cycle/octave modulation obtained to a four-octave noiseband is not likely different than that obtained to a one-octave noiseband tested at the upper or lower range of the original broadband stimulus. In the present study, SMD thresholds were obtained to noiseband stimuli of differentbandwidthsand audio-frequency regionsat different spectral modulation frequencies. The SMD thresholds were compared with the listener’s speech understanding scores to determine the relationship between SMD thresholds and performance. The goal was to determine the spectral cues (i.e. spectral modulation frequencies and audio-frequency ranges) required to model speech understanding in quiet and in noise.

OBJECTIVE The range of pitch sensations available in cochlear implants (CIs) is conventionally thought to be limited by the location of the most apical and basal electrodes. However, partial bipolar stimulation, in which current is distributed to two intracochlear electrodes and one extracochlear electrode, can produce "phantom electrode" (PE) pitch percepts that extend beyond the pitch range available with physical electrodes. The goals of this study were (1) to determine the PE configuration that generated the lowest pitch relative to monopolar (MP) stimulation of the most apical electrode and (2) to determine the amount of pitch shift produced by different PE configurations. DESIGN Ten Advanced Bionics CI users (9 unilateral and 1 bilateral), implanted with the CII or HiRes 90k implant and the HiFocus 1, HiFocus 1j, or Helix electrode arrays participated in this study. PEs were created by simultaneously stimulating the primary and compensating electrodes in opposite phase. To test different PE configurations, the proportion of current delivered to the compensating electrode (sigma) and the electrode separation between the primary and compensatory electrode (D) were varied. To estimate the relative pitch of PEs, the lowest pitched PEs with primary electrodes 4 and 8 were compared with subsets of MP electrodes (1, 2, 3, 4, 5 and 5, 6, 7, 8, 9, respectively). RESULTS In all subjects, it was possible to identify sigma and D values that produced a PE that was lower in pitch than the MP stimulation of the primary electrode. In some subjects, increasing sigma and/or D produced progressively lower pitch percepts, whereas in others, PE pitch changed nonmonotonically with sigma and/or D. The amount of PE pitch shift could be estimated only for 14 cases; in seven cases, the pitch shift was

Speech understanding by cochlear implant listeners may be limited by their ability to perceive complex spectral envelopes. Here, spectral envelope perception was characterized by spectral modulation transfer functions in which modulation detection thresholds became poorer with increasing spectral modulation frequency (SMF). Thresholds at low SMFs, less likely to be influenced by spectral resolution, were correlated with vowel and consonant identifications [Litvak, L. M. et al. (2008). J. Acoust. Soc. Am. 122, 982–991] for the same listeners; while thresholds at higher SMFs, more likely to be affected by spectral resolution, were not. Results indicate that the perception of broadly spaced spectral features is important for speech perception.

Auditory processing appears to include a series of domain-specific filtering operations that include tuning in the audio-frequency domain, followed by tuning in the temporal modulation domain, and perhaps tuning in the spectral modulation domain. To explore the possibility of tuning in the spectral modulation domain, a masking experiment was designed to measure masking patterns in the spectral modulation domain. Spectral modulation transfer functions (SMTFs) were measured for modulation frequencies from 0.25 to 14 cycles/octave superimposed on noise carriers either one octave (800-1600 Hz, 6400-12,800 Hz) or six octaves wide (200-12,800 Hz). The resulting SMTFs showed maximum sensitivity to modulation between 1 and 3 cycles/octave with reduced sensitivity above and below this region. Masked spectral modulation detection thresholds were measured for masker modulation frequencies of 1, 3, and 5 cycles/octave with a fixed modulation depth of 15 dB. The masking patterns obtained for each masker frequency and carrier band revealed tuning (maximum masking) near the masker frequency, which is consistent with the theory that spectral envelope perception is governed by a series of spectral modulation channels tuned to different spectral modulation frequencies.

Unbalanced bipolar stimulation, delivered using charge balanced pulses, was used to produce "Phantom stimulation", stimulation beyond the most apical contact of a cochlear implant's electrode array. The Phantom channel was allocated audio frequencies below 300 Hz in a speech coding strategy, conveying energy some two octaves lower than the clinical strategy and hence delivering the fundamental frequency of speech and of many musical tones. A group of 12 Advanced Bionics cochlear implant recipients took part in a chronic study investigating the fitting of the Phantom strategy and speech and music perception when using Phantom. The evaluation of speech in noise was performed immediately after fitting Phantom for the first time (Session 1) and after one month of take-home experience (Session 2). A repeated measures of analysis of variance (ANOVA) within factors strategy (Clinical, Phantom) and interaction time (Session 1, Session 2) revealed a significant effect for the interaction time and strategy. Phantom obtained a significant improvement in speech intelligibility after one month of use. Furthermore, a trend towards a better performance with Phantom (48%) with respect to F120 (37%) after 1 month of use failed to reach significance after type 1 error correction. Questionnaire results show a preference for Phantom when listening to music, likely driven by an improved balance between high and low frequencies.

Exemplary cochlear implant systems include an implantable cochlear stimulator configured to be implanted within a patient and generate a stimulation current having an adjustable current level, one or more electrodes communicatively coupled to the stimulator and configured to apply the stimulation current to one or more locations within an ear of the patient, and a probe configured to acquire sound data used to derive an acoustic reflectance of the ear. The implantable cochlear stimulator is configured to adjust the current level of the stimulation current until a change in the acoustic reflectance above a threshold is detected.

Auditory processing appears to consist of a series of domain‐specific filtering operations that separate complex stimuli into different auditory channels. This begins with tuning in the audio‐frequency domain, followed by tuning in the temporal frequency (modulation) domain, and perhaps tuning in the spectral frequency domain. To explore the hypothesis that envelope channels tuned to spectral frequency exist in the auditory system, a masking experiment was designed to measure masking patterns in the spectral domain. Noise carriers with flat spectra were either 1 (800–1600 Hz, 6400–12 800 Hz) or 6 octaves wide (200–12 800 Hz) and were shaped with sinusoidal spectral envelopes (in cycles per octave). Masker frequencies were 1, 3, or 5 cyc/oct with a spectral contrast of 20 dB. Masked contrast thresholds were measured for signal frequencies ranging from 1.5 octaves below to 2 octaves above the masker frequency. The resulting masking patterns revealed maximum masking at the masker frequency and a gradual decrease in the masking above and below the masker frequency. This tuning is consistent with the assumption of spectral envelope channels tuned to different spectral frequencies. Secondary peaks obtained in several masking patterns may suggest inhibitory interactions among separate spectral channels. [Work supported by NIH NIDCD RO1DC04403.]

Among other things, enhancing spectral contrast for a cochlear implant listener includes detecting a time domain signal. A first transformation is applied to the detected time domain signal to convert the time domain signal to a frequency domain signal. A second transformation is applied to the frequency domain signal to express the frequency domain signal as a sum of two or more components. A sensitivity of the cochlear implant listener to detect modulation of each component is obtained.

In cochlear implants, simultaneous stimulation of adjacent electrodes, can be used to shape the electric fields generated within the cochlea. For example, simultaneous in‐phase stimulation of nearby electrodes can be used to create activation patterns which may have maxima at locations that are intermediate to the locations of the stimulated electrodes. Psychophysically, such “virtual channels” give rise to intermediate pitch sensations. Simultaneous out‐of‐phase stimulation of two flanking electrodes in addition to the center electrode can be used to presumably produce more focused activation at the cost of larger overall stimulation currents. Forward masking patterns indicate that for sufficiently large compensation currents, such “focused” stimulation can lead to a more spatially contained excitation. In some cases, current focusing also could lead to sensations that are more tonal relative to monopolar. This presentation will review recent results obtained in our laboratories with both “virtual channe...

Knowledge of the internal auditory representation of spectral envelope features is critical to the understanding of auditory perception by listeners with normal and impaired hearing. Previous investigators have used forward and simultaneous masking to derive masking patterns that reveal the influence of lateral suppression and other factors on the internal representation of various spectral envelopes (e.g., narrowband noise and steady‐state vowels). The present study followed a general approach, in which the internal representation of spectral shape was estimated on the basis of spectral masking patterns obtained with sinusoidal spectral modulation. Simultaneous‐ and forward‐masked thresholds were measured for probe signals as a function of spectral modulation frequency (cycles/octave), phase, and depth (peak‐valley contrast in dB) superimposed on a noise carrier (400–6400 Hz). For relatively low modulation frequencies (