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Published Ahead-of-Print - Last Updated: April 02, 2019
The editors of this journal are pleased to offer electronic publication of accepted papers prior to print publication. These papers can be cited using the date of access and the unique DOI number. Any final changes in manuscripts will be made at the time of print publication and will be reflected in the final electronic version of the issue.

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Test/Retest Variability of the eCAP Threshold in Advanced Bionics Cochlear Implant Users
Stronks, H. Christiaan; Biesheuvel, Jan Dirk; de Vos, Johan J.; More
Ear and Hearing. ., Post Author Corrections: April 02, 2019

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Objective:
The reliability of the electrically evoked compound action potential (eCAP) threshold depends on its precision and accuracy. The precision of the eCAP threshold reflects its variability, while the accuracy of the threshold shows how close it is to the actual value. The objective of this study was to determine the test/retest variability of the eCAP threshold in Advanced Bionics cochlear implant users, which has never been reported before. We hypothesized that the test/retest variability is dependent on the presence of random noise in the recorded eCAP waveforms. If this holds true, the recorded error should be reduced by approximately the square-root of the number of averages. As secondary objectives, we assessed the effects of the slope of the amplitude growth function (AGF), cochlear location, and eCAP threshold on eCAP threshold precision. We hypothesized that steeper slopes should result in better precision of the linearly extrapolated eCAP threshold. As other studies have shown that apical regions have steeper slopes and larger eCAPs, we recorded eCAPs in three different cochlear locations. The difference of the precision between two commonly applied stimulus-artifact reduction paradigms on eCAP threshold precision was compared, namely averaging of alternating stimulus polarities (AP averaging) and forward masking (FM). FM requires the addition of more waveforms than AP averaging, and hence we expected FM to have lower precision than AP.

Design:
This was an unmasked, descriptive, and observational study with a cross-over (repeated measures) design that included 13 subjects. We recorded eCAPs on three electrode contacts: in the base, middle, and apex of the cochlea at 10 stimulus intensities. Per stimulus level, 256 eCAP waveforms were recorded. eCAP thresholds were determined by constructing AGFs and linear extrapolation to zero-amplitude. The precision of the eCAP threshold was calculated as the SD using a Monte Carlo simulation, as a function of the number of waveform averages.

Results:
The SD of the eCAP threshold was reduced by approximately the square root of two when the number of averages in the eCAP waveforms was doubled. The precision was significantly better when the slope of the AGF was steeper and was more favorable in the cochlear base than in the apex. Precision was better when AP averaging was used. Absolute eCAP threshold did not significantly affect precision. At the default number of 32 waveform averages in the Advanced Bionics system, we report a median SD of the eCAP threshold of 2 to 3 μA, with a range of 1 to 11 μA across the cochlea. Previous studies have shown that the total error, based on the 95% confidence bounds of the linear extrapolation, can be as high as −260 to +120 μA.

Conclusions:
The median variability in the eCAP threshold proved to be small compared with the total variability introduced by the linear extrapolation method. Yet there was substantial intersubject variability. Therefore, we recommend monitoring the SD during eCAP recording to facilitate informed decisions when to terminate waveform collection. From a precision perspective, AP averaging is preferable over FM as it has better precision, while fewer recordings are needed, making it the more time-efficient method of the two.

This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

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Effect of Compression on Musical Sound Quality in Cochlear Implant Users
Gilbert, Melanie; Jiradejvong, Patpong; Limb, Charles
Ear and Hearing. ., Post Author Corrections: March 29, 2019

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Objectives:
Cochlear implant (CI) users frequently report poor sound quality while listening to music, although the specific parameters responsible for this loss of sound quality remain poorly understood. Audio compression, which reduces the dynamic range (DR) for a given sound, is a ubiquitous component of signal processing used by both CI and hearing aid technology. However, the relative impact of compression for acoustic and electric hearing on music perception has not been well studied, an important consideration especially given that most compression algorithms in CIs were developed to optimize speech perception. The authors hypothesized that normal-hearing (NH) listeners would detect increased levels of compression more easily than CI users, but that both groups would perceive a loss of sound quality with increasing compression levels.

Design:
The present study utilizes the Cochlear Implant-MUltiple Stimulus with Hidden Reference and Anchor to evaluate the listener sensitivity to increasing levels of compression applied to music stimuli. The Cochlear Implant-MUltiple Stimulus with Hidden Reference and Anchor is a tool used to assess relative changes in the perceived sound quality of music across increasingly degraded listening conditions, in both CI and NH subjects. In this study, the authors applied multiple iterations of an aggressive compression algorithm to the music clips using Adobe Audition. The test conditions included 1, 3, 5, and 20 iterations sound tokens, with the 20-iteration samples serving as the Anchor stimuli. The compressed excerpts were 5 sec in length, with five clips for each of the five common musical genres (i.e., Classical, Jazz, Country, Rock, and Hip-Hop). Subjects were also presented with a Reference excerpt, which was the original music clip without any additional compression applied. CI recipients (n = 7, 11 ears) and NH listeners (n = 10) were asked to rate the sound quality of additionally compressed music as compared to the Reference.

Results:
Although both NH and CI groups could detect sound quality differences as a function of compression level, the discriminatory ability of the CI group was blunted compared to the NH group. The CI group had less variability in their responses and overall demonstrated reduced sensitivity to deterioration caused by excessive levels of compression. On average, the CI group rated the Anchor condition as only "Slightly worse" than the Reference. The music clips that were most affected by the compression were from Jazz and Hip-Hop genres and less so for Rock and Country clips. Corollary to this was a small but statistically significant impact of DR of the music clips on sound quality ratings, with narrower DR showing an association with poorer ratings.

Conclusions:
These results indicate that CI users exhibit less sensitivity to sound quality changes in music attributable to high levels of compression. These findings may account for another contributing factor to the generally poor music perception observed in CI users, particularly when listening to commercially recorded music.

This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

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Childhood Sensorineural Hearing Loss and Educational Attainment in Adulthood: Results From the HUNT Study
Idstad, Mariann; Engdahl, Bo
Ear and Hearing. ., Post Author Corrections: March 29, 2019

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Objectives:
Although the educational achievement gap between people without hearing loss and people with hearing loss is well-documented, few studies are based on large, nonclinical samples. The present study aims to investigate the educational attainment among Norwegian adults diagnosed with sensorineural hearing loss as children, compared with a matched control group of people without hearing loss.

Design:
A prospective cohort design was applied. Between 1954 and 1986, the children in the first, fourth, and/or seventh grade in all primary schools in Nord-Trøndelag County participated in the School Hearing Investigation in Nord-Trøndelag, in which they underwent audiometric screening. Those with positive results had their hearing further tested by means of pure tone audiometry at 0.25, 0.5, 1, 2, 4, and 8 kHz with air- and bone-conduction thresholds, as well as a full examination by an ear, nose, and throat (ENT) specialist. In the present study, 216 persons were classified with moderate-severe hearing loss (41 to 100 dB HL), 293 with mild hearing loss (26 to 40 dB HL), and 240 with slight hearing loss (16 to 25 dB HL). Age-matched controls were recruited from the Norwegian Health Study, which was conducted in the same county. A total of 48,606 people participated in the present study. Data on educational attainment up to 2014 was provided by Statistics Norway. Control variables comprised sex, age, mothers', and fathers' education. The relation between childhood sensorineural hearing loss and educational attainment was tested by means of multinomial logistic regression models; first for the total sample (born between 1941 and 1979), and then for two different birth cohorts born between 1941 and 1959 and between 1960 and 1979.

Results:
Percentwise, the educational attainment level in general has increased, both among people without hearing loss and people with hearing loss, and especially for women. However, 27.5% of people without hearing loss obtained higher education, whereas the corresponding numbers for those with mild or moderate-severe hearing loss were 18.8%, and 21.3%, respectively. The results from the regression analyses showed that in the total sample, compared with having primary education, people with moderate-severe or mild hearing loss were about half as likely to achieve higher education as people without hearing loss (odds ratio (OR) = 0.63 and 0.49, respectively). An interaction term between sensorineural hearing loss and sex was specified but it was not significant. In the older cohort, we found a significant association between mild hearing loss and higher education (OR = 0.40), and between moderate-severe hearing loss and secondary education (OR = 0.65). In the younger cohort, there was a significant association between mild hearing loss and higher education (OR = 0.56) and between slight hearing loss and secondary education (OR = 0.61).

Conclusions:
The results from this study indicate that the achievement gap between people without hearing loss and those with hearing loss remains. Future studies should try to pinpoint what might be hindering people with slight, mild, moderate, or severe hearing loss in pursuing higher education. Parents, health personnel, institutions for higher education, and policy makers alike should take this into consideration when making plans and policies.

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The Effect of Otoacoustic Emission Stimulus Level on the Strength and Detectability of the Medial Olivocochlear Reflex
Lewis, James D.
Ear and Hearing. ., Post Author Corrections: March 19, 2019

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Objectives:
Previous work demonstrates the importance of a high signal to noise ratio (SNR) when using transient evoked otoacoustic emissions (TEOAEs) to assay the medial olivocochlear reflex (MOCR). Increasing stimulus level provides one means to increase TEOAE SNR. However, this may come at the expense of a smaller MOCR effect. It is not clear whether the gain in SNR associated with the use of higher stimulus levels outweighs the disadvantage of a potentially smaller MOCR effect. The present study investigated the strength and detectability of the MOCR when assayed using TEOAEs at different stimulus levels. The hypothesis was that although the strength of the MOCR decreases with increasing stimulus level, the occurrence of statistically significant MOCR effects increases due to an increase in TEOAE SNR.

Design:
Twenty-five young adult females with normal hearing participated in the study. TEOAEs were measured in the right ear with and without broadband noise presented in the left ear. The strength of the MOCR was quantified as the percent difference in the TEOAE between the contralateral noise and quiet conditions. Statistical bootstrapping was used to detect significant MOCR effects in individual subjects across different frequency bands and stimulus levels. The relationship between a detectable MOCR (response variable) and frequency, stimulus level, TEOAE SNR, MOCR strength, and subject (predictor variables) was evaluated using generalized linear mixed-effect models.

Results:
The number of statistically significant MOCR effects increased with stimulus level at all frequencies. Occurrence was highest for the 2-kHz TEOAE frequency band and lowest for the 4-kHz frequency band. The strength of the MOCR decreased with increasing click level. TEOAE SNR, MOCR strength, and stimulus level were significant predictors of a detectable MOCR: The likelihood of a detectable MOCR increased with TEOAE SNR, MOCR strength, and stimulus level.

Conclusions:
Despite a reduction in the strength of the MOCR with increasing stimulus level, the detectability of the MOCR increased. This is due, in part, to an increase in TEOAE SNR with stimulus level. For clinical implementation of TEOAE-based MOCR assays, achieving a high SNR is necessary to permit the detection of the MOCR in individual patients.

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Reliability of Measures Intended to Assess Threshold-Independent Hearing Disorders
Kamerer, Aryn M.; Kopun, Judy G.; Fultz, Sara E.; More
Ear and Hearing. ., Post Author Corrections: March 14, 2019

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Objectives:
Recent animal studies have shown that noise exposure can cause cochlear synaptopathy without permanent threshold shift. Because the noise exposure preferentially damaged auditory nerve fibers that processed suprathreshold sounds (low-spontaneous rate fibers), it has been suggested that synaptopathy may underlie suprathreshold hearing deficits in humans. Recently, several researchers have suggested measures to identify the pathology or pathologies underlying suprathreshold hearing deficits in humans based on results from animal studies; however, the reliability of some of these measures have not been assessed. The purpose of this study was to assess the test–retest reliability of measures that may have the potential to relate suprathreshold hearing deficits to site(s)-of-lesion along the peripheral auditory system in humans.

Design:
Adults with audiometric normal hearing were tested on a battery of behavioral and physiologic measures that included (1) thresholds in quiet (TIQ), (2) thresholds in noise (TIN), (3) frequency-modulation detection threshold (FMDT), (4) word recognition in four listening conditions, (5) distortion-product otoacoustic emissions (DPOAE), (6) middle ear muscle reflex (MEMR), (7) tone burst-elicited auditory brainstem response (tbABR), and (8) speech-evoked ABR (sABR). Data collection for each measure was repeated over two visits separated by at least one week. The residuals of the correlation between the suprathreshold measures and TIQ serve as functional and quantitative proxies for threshold-independent hearing disorders because they represent the portion of the raw measures that is not dependent on TIQ. Reliability of the residual measures was assessed using intraclass correlation (ICC).

Results:
Reliability for the residual measures was good (ICC ≥ 0.75) for FMDT, DPOAEs, and MEMR. Residual measures showing moderate reliability (0.5 ≤ ICC < 0.75) were tbABR wave I amplitude, TIN, and word recognition in quiet, noise, and time-compressed speech with reverberation. Wave V of the tbABR, waves of the sABR, and recognition of time-compressed words had poor test–retest reliability (ICC < 0.5).

Conclusions:
Reliability of residual measures was mixed, suggesting that care should be taken when selecting measures for diagnostic tests of threshold-independent hearing disorders. Quantifying hidden hearing loss as the variance in suprathreshold measures of auditory function that is not due to TIQ may provide a reliable estimate of threshold-independent hearing disorders in humans.

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Factors Affecting Bimodal Benefit in Pediatric Mandarin-Speaking Chinese Cochlear Implant Users
Liu, Yang-Wenyi; Tao, Duo-Duo; Chen, Bing; More
Ear and Hearing. ., Post Author Corrections: March 14, 2019

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Objectives:
While fundamental frequency (F0) cues are important to both lexical tone perception and multitalker segregation, F0 cues are poorly perceived by cochlear implant (CI) users. Adding low-frequency acoustic hearing via a hearing aid in the contralateral ear may improve CI users' F0 perception. For English-speaking CI users, contralateral acoustic hearing has been shown to improve perception of target speech in noise and in competing talkers. For tonal languages such as Mandarin Chinese, F0 information is lexically meaningful. Given competing F0 information from multiple talkers and lexical tones, contralateral acoustic hearing may be especially beneficial for Mandarin-speaking CI users' perception of competing speech.

Design:
Bimodal benefit (CI+hearing aid – CI-only) was evaluated in 11 pediatric Mandarin-speaking Chinese CI users. In experiment 1, speech recognition thresholds (SRTs) were adaptively measured using a modified coordinated response measure test; subjects were required to correctly identify 2 keywords from among 10 choices in each category. SRTs were measured with CI-only or bimodal listening in the presence of steady state noise (SSN) or competing speech with the same (M+M) or different voice gender (M+F). Unaided thresholds in the non-CI ear and demographic factors were compared with speech performance. In experiment 2, SRTs were adaptively measured in SSN for recognition of 5 keywords, a more difficult listening task than the 2-keyword recognition task in experiment 1.

Results:
In experiment 1, SRTs were significantly lower for SSN than for competing speech in both the CI-only and bimodal listening conditions. There was no significant difference between CI-only and bimodal listening for SSN and M+F ( p > 0.05); SRTs were significantly lower for CI-only than for bimodal listening for M+M ( p < 0.05), suggesting bimodal interference. Subjects were able to make use of voice gender differences for bimodal listening ( p < 0.05) but not for CI-only listening ( p > 0.05). Unaided thresholds in the non-CI ear were positively correlated with bimodal SRTs for M+M ( p < 0.006) but not for SSN or M+F. No significant correlations were observed between any demographic variables and SRTs ( p > 0.05 in all cases). In experiment 2, SRTs were significantly lower with two than with five keywords ( p < 0.05). A significant bimodal benefit was observed only for the 5-keyword condition ( p < 0.05).

Conclusions:
With the CI alone, subjects experienced greater interference with competing speech than with SSN and were unable to use voice gender difference to segregate talkers. For the coordinated response measure task, subjects experienced no bimodal benefit and even bimodal interference when competing talkers were the same voice gender. A bimodal benefit in SSN was observed for the five-keyword condition but not for the two-keyword condition, suggesting that bimodal listening may be more beneficial as the difficulty of the listening task increased. The present data suggest that bimodal benefit may depend on the type of masker and/or the difficulty of the listening task.

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Effects of Forward- and Emitted-Pressure Calibrations on the Variability of Otoacoustic Emission Measurements Across Repeated Probe Fits
Maxim, Tom; Shera, Christopher A.; Charaziak, Karolina K.; More
Ear and Hearing. ., Post Author Corrections: March 14, 2019

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Objective:
The stimuli used to evoke otoacoustic emissions (OAEs) are typically calibrated based on the total SPL measured at the probe microphone. However, due to the acoustics of the ear-canal space (i.e., standing-wave interference), this method can underestimate the stimulus pressure reaching the tympanic membrane at certain frequencies. To mitigate this effect, stimulus calibrations based on forward pressure level (FPL) can be applied. Furthermore, the influence of ear-canal acoustics on measured OAE levels can be compensated by expressing them in emitted pressure level (EPL). To date, studies have used artificial shallow versus deep probe fits to assess the effects of calibration method on changes in probe insertion. In an attempt to better simulate a clinical setting, the combined effects of FPL calibration of stimulus level and EPL compensation of OAE level on response variability during routine (noncontrived) probe fittings were examined.

Design:
The distortion component of the distortion-product OAE (DPOAE) and the stimulus-frequency OAE (SFOAE) were recorded at low and moderate stimulus levels in 20 normal-hearing young-adult subjects across a five-octave range. In each subject, three different calibration approaches were compared: (1) the conventional SPL-based stimulus calibration with OAE levels expressed in SPL; (2) FPL stimulus calibration with OAEs expressed in SPL; and (3) FPL stimulus calibration with OAEs expressed in EPL. Test and retest measurements were obtained during the same session and, in a subset of subjects, several months after the initial test. The effects of these different procedures on the inter- and intra-subject variability of OAE levels were assessed across frequency and level.

Results:
There were no significant differences in the inter-subject variability of OAE levels across the three calibration approaches. However, there was a significant effect on OAE intra-subject variability. The FPL/EPL approach resulted in the overall lowest test-rest differences in DPOAE level for frequencies above 4 kHz, where standing-wave interference is strongest. The benefit was modest, ranging on average from 0.5 to 2 dB and was strongest at the lower stimulus level. SFOAE level variability did not show significant differences among the three procedures, perhaps due to insufficient signal-to-noise ratio and nonoptimized stimulus levels. Correlations were found between the short-term replicability of DPOAEs and the benefit derived from the FPL/EPL procedure: the more variable the DPOAE, the stronger the benefit conferred by the advanced calibration methods.

Conclusions:
Stimulus and response calibration procedures designed to mitigate the effects of standing-wave interference on both the stimulus and the OAE enhance the repeatability of OAE measurements and reduce their dependence on probe position, even when probe shifts are small. Modest but significant improvements in short-term test-retest repeatability were observed in the mid- to high-frequency region when using combined FPL/EPL procedures. The authors posit that the benefit will be greater in a more heterogeneous group of subjects and when different testers participate in the fitting and refitting of subjects, which is a common practice in the audiology clinic. The impact of calibration approach on OAE inter-subject variability was not significant, possibly due to a homogeneous subject population and because factors other than probe position are at play.

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Mechanisms of Localization and Speech Perception with Colocated and Spatially Separated Noise and Speech Maskers Under Single-Sided Deafness with a Cochlear Implant
Dirks, Coral; Nelson, Peggy B.; Sladen, Douglas P.; More
Ear and Hearing. ., Post Author Corrections: March 07, 2019

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Objectives:
This study tested listeners with a cochlear implant (CI) in one ear and acoustic hearing in the other ear, to assess their ability to localize sound and to understand speech in collocated or spatially separated noise or speech maskers.

Design:
Eight CI listeners with contralateral acoustic hearing ranging from normal hearing to moderate sensorineural hearing loss were tested. Localization accuracy was measured in five of the listeners using stimuli that emphasized the separate contributions of interaural level differences (ILDs) and interaural time differences (ITD) in the temporal envelope and/or fine structure. Sentence recognition was tested in all eight CI listeners, using collocated and spatially separated speech-shaped Gaussian noise and two-talker babble. Performance was compared with that of age-matched normal-hearing listeners via loudspeakers or via headphones with vocoder simulations of CI processing.

Results:
Localization improved with the CI but only when high-frequency ILDs were available. Listeners experienced no additional benefit via ITDs in the stimulus envelope or fine structure using real or vocoder-simulated CIs. Speech recognition in two-talker babble improved with a CI in seven of the eight listeners when the target was located at the front and the babble was presented on the side of the acoustic-hearing ear, but otherwise showed little or no benefit of a CI.

Conclusion:
Sound localization can be improved with a CI in cases of significant residual hearing in the contralateral ear, but only for sounds with high-frequency content, and only based on ILDs. In speech understanding, the CI contributed most when it was in the ear with the better signal to noise ratio with a speech masker.

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Auditory Localization and Spatial Release From Masking in Children With Suspected Auditory Processing Disorder
Boothalingam, Sriram; Purcell, David W.; Allan, Chris; More
Ear and Hearing. ., Post Author Corrections: March 07, 2019

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Objectives:
We sought to investigate whether children referred to our audiology clinic with a complaint of listening difficulty, that is, suspected of auditory processing disorder (APD), have difficulties localizing sounds in noise and whether they have reduced benefit from spatial release from masking.

Design:
Forty-seven typically hearing children in the age range of 7 to 17 years took part in the study. Twenty-one typically developing (TD) children served as controls, and the other 26 children, referred to our audiology clinic with listening problems, were the study group: suspected APD (sAPD). The ability to localize a speech target (the word "baseball") was measured in quiet, broadband noise, and speech-babble in a hemi-anechoic chamber. Participants stood at the center of a loudspeaker array that delivered the target in a diffused noise-field created by presenting independent noise from four loudspeakers spaced 90° apart starting at 45°. In the noise conditions, the signal-to-noise ratio was varied between −12 and 0 dB in 6-dB steps by keeping the noise level constant at 66 dB SPL and varying the target level. Localization ability was indexed by two metrics, one assessing variability in lateral plane [lateral scatter (Lscat)] and the other accuracy in the front/back dimension [front/back percent correct (FBpc)]. Spatial release from masking (SRM) was measured using a modified version of the Hearing in Noise Test (HINT). In this HINT paradigm, speech targets were always presented from the loudspeaker at 0°, and a single noise source was presented either at 0°, 90°, or 270° at 65 dB A. The SRM was calculated as the difference between the 50% correct HINT speech reception threshold obtained when both speech and noise were collocated at 0° and when the noise was presented at either 90° or 270°.

Results:
As expected, in both groups, localization in noise improved as a function of signal-to-noise ratio. Broadband noise caused significantly larger disruption in FBpc than in Lscat when compared with speech babble. There were, however, no group effects or group interactions, suggesting that the children in the sAPD group did not differ significantly from TD children in either localization metric (Lscat and FBpc). While a significant SRM was observed in both groups, there were no group effects or group interactions. Collectively, the data suggest that children in the sAPD group did not differ significantly from the TD group for either binaural measure investigated in the study.

Conclusions:
As is evident from a few poor performers, some children with listening difficulties may have difficulty in localizing sounds and may not benefit from spatial separation of speech and noise. However, the heterogeneity in APD and the variability in our data do not support the notion that localization is a global APD problem. Future studies that employ a case study design might provide more insights.

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Bone Conduction Amplification in Children: Stimulation via a Percutaneous Abutment versus a Transcutaneous Softband
Pittman, Andrea L.
Ear and Hearing. ., Post Author Corrections: March 07, 2019

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Objectives:
Research suggests that the speech perception of children using bone conduction amplification improves if the device is coupled to an implanted abutment rather than to a softband. The purpose of the present study was to determine if the benefit of direct stimulation via an abutment is limited to small improvements in speech perception or if similar or greater benefits occur for other auditory tasks important for learning and communication.

Design:
Fourteen children (7 to 15 years of age) with bilateral conductive and three children with unilateral conductive or sensorineural hearing loss were enrolled. Each child completed four tasks while using a bone conduction device coupled to an implanted abutment and with the device coupled to a softband. The two devices were worn at the same time and activated one at a time for testing. The children completed four tasks under each coupling condition: (a) a traditional word recognition task, (b) an auditory lexical decision task in which the children repeated aloud, and indicated the category of, real and nonsense words, (c) a nonsense-word detection task which required the children to identify nonsense words within short sentences, and (d) a rapid word learning task in which the children learned to associate nonsense words with novel images.

Results:
Regression analyses revealed that age, duration of device use, in-situ hearing thresholds, or device output did not account for a significant portion of the variability in performance for any of the four tasks. Repeated-measures analysis of variance revealed significant increases in word recognition with the abutment as well as significantly better performance for the lexical decision and word learning tasks. The data indicated that the children with the poorest performance with the softband tended to benefit most with the abutment. Also, the younger children showed improved performance for more tasks with the abutment than the older children. No difference between coupling conditions was observed for nonsense-word detection.

Conclusions:
The improved recognition of familiar words, categorization and repetition of nonsense words, and speed of word learning with the abutment suggests that direct stimulation provides a higher-quality signal than indirect stimulation through a softband. Because these processes are important for vocabulary acquisition and language development, children may experience long-term benefits of direct stimulation for academic, social, and vocational purposes in addition to immediate improvement in communication.

This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

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Speech Envelope Enhancement Instantaneously Effaces Atypical Speech Perception in Dyslexia
Van Hirtum, Tilde; Moncada-Torres, Arturo; Ghesquière, Pol; More
Ear and Hearing. ., Post Author Corrections: March 05, 2019

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Objectives:
Increasing evidence exists that poor speech perception abilities precede the phonological deficits typically observed in dyslexia, a developmental disorder in learning to read. Impaired processing of dynamic features of speech, such as slow amplitude fluctuations and transient acoustic cues, disrupts effortless tracking of the speech envelope and constrains the development of adequate phonological skills. In this study, a speech envelope enhancement (EE) strategy was implemented to reduce speech perception deficits by students with dyslexia. The EE emphasizes onset cues and reinforces the temporal structure of the speech envelope specifically.

Design:
Speech perception was assessed in 42 students with and without dyslexia using a sentence repetition task in a speech-weighted background noise. Both natural and vocoded speech were used to assess the contribution of the temporal envelope on the speech perception deficit. Their envelope-enhanced counterparts were added to each baseline condition to administer the effect of the EE algorithm. In addition to speech-in-noise perception, general cognitive abilities were assessed.

Results:
Results demonstrated that students with dyslexia not only benefit from EE but benefit more from it than typical readers. Hence, EE completely normalized speech reception thresholds for students with dyslexia under adverse listening conditions. In addition, a correlation between speech perception deficits and phonological processing was found for students with dyslexia, further supporting the relation between speech perception abilities and reading skills. Similar results and relations were found for conditions with natural and vocoded speech, providing evidence that speech perception deficits in dyslexia stem from difficulties in processing the temporal envelope.

Conclusions:
Using speech EE, speech perception skills in students with dyslexia were improved passively and instantaneously, without requiring any explicit learning. In addition, the observed positive relationship between speech processing and advanced phonological skills opens new avenues for specific intervention strategies that directly target the potential core deficit in dyslexia.

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Different Associations between Auditory Function and Cognition Depending on Type of Auditory Function and Type of Cognition
Danielsson, Henrik; Humes, Larry E; Rönnberg, Jerker
Ear and Hearing. ., Post Author Corrections: February 22, 2019

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Objectives:
Previous studies strongly suggest that declines in auditory threshold can lead to impaired cognition. The aim of this study was to expand that picture by investigating how the relationships between age, auditory function, and cognitive function vary with the types of auditory and cognitive function considered.

Design:
Three auditory constructs (threshold, temporal-order identification, and gap detection) were modeled to have an effect on four cognitive constructs (episodic long-term memory, semantic long-term memory, working memory, and cognitive processing speed) together with age that could have an effect on both cognitive and auditory constructs. The model was evaluated with structural equation modeling of the data from 213 adults ranging in age from 18 to 86 years.

Results:
The model provided good a fit to the data. Regarding the auditory measures, temporal-order identification had the strongest effect on the cognitive functions, followed by weaker indirect effects for gap detection and nonsignificant effects for threshold. Regarding the cognitive measures, the association with audition was strongest for semantic long-term memory and working memory but weaker for episodic long-term memory and cognitive speed. Age had a very strong effect on threshold and cognitive speed, a moderate effect on temporal-order identification, episodic long-term memory, and working memory, a weak effect on gap detection, and nonsignificant, close to zero effect on semantic long-term memory.

Conclusions:
The result shows that auditory temporal-order function has the strongest effect on cognition, which has implications both for which auditory concepts to include in cognitive hearing science experiments and for practitioners. The fact that the total effect of age was different for different aspects of cognition and partly mediated via auditory concepts is also discussed.

This is an open access article distributed under the Creative Commons Attribution License 4.0 (CCBY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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A Longitudinal Analysis of Pressurized Wideband Absorbance Measures in Healthy Young Infants
Wali, Hamzah A; Mazlan, Rafidah; Kei, Joseph
Ear and Hearing. ., Post Author Corrections: February 22, 2019

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Abstract:
Objectives:
Wideband absorbance (WBA) is an emerging technology to evaluate the conductive pathway (outer and middle ear) in young infants. While a wealth of research has been devoted to measuring WBA at ambient pressure, few studies have investigated the use of pressurized WBA with this population. The purpose of this study was to investigate the effect of age on WBA measured under pressurized conditions in healthy infants from 0 to 6 months of age.

Design:
Forty-four full-term healthy neonates (17 males and 27 females) participated in a longitudinal study. The neonates were assessed at 1-month intervals from 0 to 6 months of age using high-frequency tympanometry, acoustic stapedial reflex, distortion product otoacoustic emissions, and pressurized WBA. The values of WBA at tympanometric peak pressure (TPP) and 0 daPa across the frequencies from 0.25 to 8 kHz were analyzed as a function of age.

Results:
A linear mixed model analysis, applied to the data, revealed significantly different WBA patterns among the age groups. In general, WBA measured at TPP and 0 daPa decreased at low frequencies (<0.4 kHz) and increased at high frequencies (2 to 5and 8 kHz) with age. Specifically, WBA measured at TPP and 0 daPa in 3- to 6-month-olds was significantly different from that of 0- to 2-month-olds at low (0.25 to 0.31 kHz) and high (2 to 5 and 8 kHz) frequencies. However, there were no significant differences between WBA measured at TPP and 0 daPa for infants from 3 to 6 months of age.

Conclusions:
The present study provided clear evidence of maturation of the outer and middle ear system in healthy infants from birth to 6 months. Therefore, age-specific normative data of pressurized WBA are warranted.

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Benefit of Higher Maximum Force Output on Listening Effort in Bone-Anchored Hearing System Users: A Pupillometry Study
Bianchi, Federica; Wendt, Dorothea; Wassard, Christina; More
Ear and Hearing. ., Post Author Corrections: February 21, 2019

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Objectives:
The aim of this study was to compare listening effort, as estimated via pupillary response, during a speech-in-noise test in bone-anchored hearing system (BAHS) users wearing three different sound processors. The three processors, Ponto Pro (PP), Ponto 3 (P3), and Ponto 3 SuperPower (P3SP), differ in terms of maximum force output (MFO) and MFO algorithm. The hypothesis was that listeners would allocate lower listening effort with the P3SP than with the PP, as a consequence of a higher MFO and, hence, fewer saturation artifacts in the signal.

Design:
Pupil dilations were recorded in 21 BAHS users with a conductive or mixed hearing loss, during a speech-in-noise test performed at positive signal-to-noise ratios (SNRs), where the speech and noise levels were individually adjusted to lead to 95% correct intelligibility with the PP. The listeners had to listen to a sentence in noise, retain it for 3 seconds and then repeat it, while an eye-tracking camera recorded their pupil dilation. The three sound processors were tested in random order with a single-blinded experimental design. Two conditions were performed at the same SNR: Condition 1, where the speech level was designed to saturate the PP but not the P3SP, and condition 2, where the overall sound level was decreased relative to condition 1 to reduce saturation artifacts.

Results:
The P3SP led to higher speech intelligibility than the PP in both conditions, while the performance with the P3 did not differ from the performance with the PP and the P3SP. Pupil dilations were analyzed in terms of both peak pupil dilation (PPD) and overall pupil dilation via growth curve analysis (GCA). In condition 1, a significantly lower PPD, indicating a decrease in listening effort, was obtained with the P3SP relative to the PP. The PPD obtained with the P3 did not differ from the PPD obtained with the other two sound processors. In condition 2, no difference in PPD was observed across the three processors. The GCA revealed that the overall pupil dilation was significantly lower, in both conditions, with both the P3SP and the P3 relative to the PP, and, in condition 1, also with the P3SP relative to the P3.

Conclusions:
The overall effort to process a moderate to loud speech signal was significantly reduced by using a sound processor with a higher MFO (P3SP and P3), as a consequence of fewer saturation artifacts. These findings suggest that sound processors with a higher MFO may help BAHS users in their everyday listening scenarios, in particular in noisy environments, by improving sound quality and, thus, decreasing the amount of cognitive resources utilized to process incoming speech sounds.

This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

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A Comparison of Electrical Stimulation Levels Across Ears for Children With Sequential Bilateral Cochlear Implants
Galvin, Karyn L.; Abdi, Roghayeh; Dowell, Richard C.; More
Ear and Hearing. ., Post Author Corrections: February 21, 2019

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Abstract:
Objectives:
To compare threshold and comfortable levels between a first and second cochlear implant (CI) for children, and to consider if the degree of difference between CIs was related to the age at bilateral implantation or the time between implants. A secondary objective was to examine the changes in levels over time for each CI .

Design:
Fifty-seven participants were selected from the 146 children and young adults who received a first Nucleus CI as a child, and received a second implant at the Royal Victorian Eye and Ear Hospital between September 2003 and December 2011. Exclusion criteria included an older implant type, incomplete array insertion, incomplete data available, and a pulse width higher than the default. Using measurements from clinical sessions, the threshold levels, comfortable levels, and dynamic range of electrical stimulation were compared at three electrode array regions and at the "initial" (first 10 weeks), 2-year, and 5-year postoperative time points. The T-ratio and C-ratio for each array region and each time point were calculated by dividing each mean (n = 3 electrodes) level for the second implant by that for the first implant.

Results:
The T-ratio was generally not significantly different to one, indicating no differences in threshold levels between the second and first implants; however, threshold levels were lower for the second implant in the apical region at the initial time point, and there was a significant difference in threshold levels in the apical region for children with a Contour Advance array for the second implant and an older-style array (i.e., Contour) for the first implant. For each implant individually, there were no significant changes in threshold levels across time. The C-ratio was significantly <1 at all electrode array regions at all time points, indicating lower comfortable levels for the second implant. The difference between implants was greater for children with variable array type (i.e., a Contour Advance array for the second implant and an older-style Contour or Straight array for the first implant). There was a significant increase in the C-ratio between the initial and 2-year time points, driven by an increase in comfortable levels for the second implant over this time period. A longer time between implants was associated with a narrower dynamic range, due to lower comfortable levels, for the second implant.

Conclusions:
For this sequentially implanted group, threshold levels were similar between implants, with some differences in cases with a newer array type for the second implant. Comfortable levels were lower for the second implant; although this difference decreased between the initial and 2-year postoperative time points, it was still evident at 5 years postoperative. A longer time between implants was associated with a narrower dynamic range. These findings are likely to apply to children using other brands of implant. Knowing what to expect in terms of programming children with a second implant will help clinicians to recognize and respond to unexpected outcomes. The work raises important questions to be addressed in future research regarding the implications of the programming outcomes for actual listening performance.

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Neurophysiological Differences in Emotional Processing by Cochlear Implant Users, Extending Beyond the Realm of Speech
Deroche, Mickael L. D.; Felezeu, Mihaela; Paquette, Sébastien; More
Ear and Hearing. ., Post Author Corrections: February 11, 2019

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Objective:
Cochlear implants (CIs) restore a sense of hearing in deaf individuals. However, they do not transmit the acoustic signal with sufficient fidelity, leading to difficulties in recognizing emotions in voice and in music. The study aimed to explore the neurophysiological bases of these limitations.

Design:
Twenty-two adults (18 to 70 years old) with CIs and 22 age-matched controls with normal hearing participated. Event-related potentials (ERPs) were recorded in response to emotional bursts (happy, sad, or neutral) produced in each modality (voice or music) that were for the most part correctly identified behaviorally.

Results:
Compared to controls, the N1 and P2 components were attenuated and prolonged in CI users. To a smaller degree, N1 and P2 were also attenuated and prolonged in music compared to voice, in both populations. The N1–P2 complex was emotion-dependent (e.g., reduced and prolonged response to sadness), but this was also true in both populations. In contrast, the later portion of the response, between 600 and 850 ms, differentiated happy and sad from neutral stimuli in normal hearing but not in CI listeners.

Conclusions:
The early portion of the ERP waveform reflected primarily the general reduction in sensory encoding by CI users (largely due to CI processing itself), whereas altered emotional processing (by CI users) could be found in the later portion of the ERP and extended beyond the realm of speech.

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Auditory Evoked Responses in Older Adults With Normal Hearing, Untreated, and Treated Age-Related Hearing Loss
McClannahan, Katrina S.; Backer, Kristina C.; Tremblay, Kelly L.
Ear and Hearing. ., Post Author Corrections: February 11, 2019

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Objectives:
The goal of this study was to identify the effects of auditory deprivation (age-related hearing loss) and auditory stimulation (history of hearing aid use) on the neural registration of sound across two stimulus presentation conditions: (1) equal sound pressure level and (2) equal sensation level.

Design:
We used a between-groups design, involving three groups of 14 older adults (n = 42; 62 to 84 years): (1) clinically defined normal hearing (≤25 dB from 250 to 8000 Hz, bilaterally), (2) bilateral mild–moderate/moderately severe sensorineural hearing loss who have never used hearing aids, and (3) bilateral mild–moderate/moderately severe sensorineural hearing loss who have worn bilateral hearing aids for at least the past 2 years.

Results:
There were significant delays in the auditory P1-N1-P2 complex in older adults with hearing loss compared with their normal hearing peers when using equal sound pressure levels for all participants. However, when the degree and configuration of hearing loss were accounted for through the presentation of equal sensation level stimuli, no latency delays were observed. These results suggest that stimulus audibility modulates P1-N1-P2 morphology and should be controlled for when defining deprivation and stimulus-related neuroplasticity in people with hearing loss. Moreover, a history of auditory stimulation, in the form of hearing aid use, does not appreciably alter the neural registration of unaided auditory evoked brain activity when quantified by the P1-N1-P2.

Conclusions:
When comparing auditory cortical responses in older adults with and without hearing loss, stimulus audibility, and not hearing loss–related neurophysiological changes, results in delayed response latency for those with age-related hearing loss. Future studies should carefully consider stimulus presentation levels when drawing conclusions about deprivation- and stimulation-related neuroplasticity. Additionally, auditory stimulation, in the form of a history of hearing aid use, does not significantly affect the neural registration of sound when quantified using the P1-N1-P2–evoked response.

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Measures of Listening Effort Are Multidimensional
Alhanbali, Sara; Dawes, Piers; Millman, Rebecca E.; More
Ear and Hearing. ., Post Author Corrections: February 06, 2019

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Objectives:
Listening effort can be defined as the cognitive resources required to perform a listening task. The literature on listening effort is as confusing as it is voluminous: measures of listening effort rarely correlate with each other and sometimes result in contradictory findings. Here, we directly compared simultaneously recorded multimodal measures of listening effort. After establishing the reliability of the measures, we investigated validity by quantifying correlations between measures and then grouping-related measures through factor analysis.

Design:
One hundred and sixteen participants with audiometric thresholds ranging from normal to severe hearing loss took part in the study (age range: 55 to 85 years old, 50.3% male). We simultaneously measured pupil size, electroencephalographic alpha power, skin conductance, and self-report listening effort. One self-report measure of fatigue was also included. The signal to noise ratio (SNR) was adjusted at 71% criterion performance using sequences of 3 digits. The main listening task involved correct recall of a random digit from a sequence of six presented at a SNR where performance was around 82 to 93%. Test–retest reliability of the measures was established by retesting 30 participants 7 days after the initial session.

Results:
With the exception of skin conductance and the self-report measure of fatigue, interclass correlation coefficients (ICC) revealed good test–retest reliability (minimum ICC: 0.71). Weak or nonsignificant correlations were identified between measures. Factor analysis, using only the reliable measures, revealed four underlying dimensions: factor 1 included SNR, hearing level, baseline alpha power, and performance accuracy; factor 2 included pupillometry; factor 3 included alpha power (during speech presentation and during retention); factor 4 included self-reported listening effort and baseline alpha power.

Conclusions:
The good ICC suggests that poor test reliability is not the reason for the lack of correlation between measures. We have demonstrated that measures traditionally used as indicators of listening effort tap into multiple underlying dimensions. We therefore propose that there is no "gold standard" measure of listening effort and that different measures of listening effort should not be used interchangeably. When choosing method(s) to measure listening effort, the nature of the task and aspects of increased listening demands that are of interest should be taken into account. The findings of this study provide a framework for understanding and interpreting listening effort measures.

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Correlates of Hearing Aid Use in UK Adults: Self-Reported Hearing Difficulties, Social Participation, Living Situation, Health, and Demographics
Sawyer, Chelsea S.; Armitage, Christopher J.; Munro, Kevin J.; More
Ear and Hearing. ., Post Author Corrections: January 17, 2019

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Objectives:
Hearing impairment is ranked fifth globally for years lived with disability, yet hearing aid use is low among individuals with a hearing impairment. Identifying correlates of hearing aid use would be helpful in developing interventions to promote use. To date, however, no studies have investigated a wide range of variables, this has limited intervention development. The aim of the present study was to identify correlates of hearing aid use in adults in the United Kingdom with a hearing impairment. To address limitations in previous studies, we used a cross-sectional analysis to model a wide range of potential correlates simultaneously to provide better evidence to aid intervention development.

Design:
The research was conducted using the UK Biobank Resource. A cross-sectional analysis of hearing aid use was conducted on 18,730 participants aged 40 to 69 years old with poor hearing, based on performance on the Digit Triplet test.

Results:
Nine percent of adults with poor hearing in the cross-sectional sample reported using a hearing aid. The strongest correlate of hearing aid use was self-reported hearing difficulties (odds ratio [OR] = 110.69 [95% confidence interval {CI} = 65.12 to 188.16]). Individuals who were older were more likely to use a hearing aid: for each additional year of age, individuals were 5% more likely to use a hearing aid (95% CI = 1.04 to 1.06). People with tinnitus (OR = 1.43 [95% CI = 1.26 to 1.63]) and people with a chronic illness (OR = 1.97 [95% CI = 1.71 to 2.28]) were more likely to use a hearing aid. Those who reported an ethnic minority background (OR = 0.53 [95% CI = 0.39 to 0.72]) and those who lived alone (OR = 0.80 [95% CI = 0.68 to 0.94]) were less likely to use a hearing aid.

Conclusions:
Interventions to promote hearing aid use need to focus on addressing reasons for the perception of hearing difficulties and how to promote hearing aid use. Interventions to promote hearing aid use may need to target demographic groups that are particularly unlikely to use hearing aids, including younger adults, those who live alone and those from ethnic minority backgrounds.

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Effects of Reverberation on the Relation Between Compression Speed and Working Memory for Speech-in-Noise Perception
Reinhart, Paul; Zahorik, Pavel; Souza, Pamela
Ear and Hearing. ., Post Author Corrections: January 16, 2019

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Objectives:
Previous study has suggested that when listening in modulated noise, individuals benefit from different wide dynamic range compression (WDRC) speeds depending on their working memory ability. Reverberation reduces the modulation depth of signals and may impact the relation between WDRC speed and working memory. The purpose of this study was to examine this relation across a range of reverberant conditions.

Design:
Twenty-eight older listeners with mild-to-moderate sensorineural hearing impairment were recruited in the present study. Individual working memory was measured using a Reading Span test. Sentences were combined with noise at two signal to noise ratios (2 and 5 dB SNR), and reverberation was simulated at a range of reverberation times (0.00, 0.75, 1.50, and 3.00 sec). Speech intelligibility was measured in listeners when listening to the sentences processed with simulated fast-acting and slow-acting WDRC conditions.

Results:
There was a significant relation between WDRC speed and working memory with minimal or no reverberation. Consistent with previous research, this relation was such that individuals with high working memory had higher speech intelligibility with fast-acting WDRC, and individuals with low working memory performed better with slow-acting WDRC. However, at longer reverberation times, there was no relation between WDRC speed and working memory.

Conclusions:
Consistent with previous studies, results suggest that there is an advantage of tailoring WDRC speed based on an individual's working memory under anechoic conditions. However, the present results further suggest that there may not be such a benefit in reverberant listening environments due to reduction in signal modulation.

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Ear and Hearing
The following 4 items were added to PAP on April 02, 2019.
Research Article: PDF Only
Stronks, H. Christiaan; Biesheuvel, Jan Dirk; de Vos, Johan J.; Boot, Martijn S.; Briaire, Jeroen J.; Frijns, Johan H. M.
Gilbert, Melanie; Jiradejvong, Patpong; Limb, Charles
Idstad, Mariann; Engdahl, Bo
Perspectives: PDF Only
Klyn, Niall A. M.; Kleindienst Robler, Samantha; Bogle, Jamie; Alfakir, Razan; Nielsen, Donald W.; Griffith, James W.; Carlson, Deborah L.; Lundy, Larry; Dhar, Sumitrajit; Zapala, David A.

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