Journal articles: 'Cochlear Gain Reduction'

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Strickland, Elizabeth A., Elin Roverud, and Kristina DeRoy Milvae. "Behavioral explorations of cochlear gain reduction." Journal of the Acoustical Society of America 135, no. 4 (April 2014): 2384. http://dx.doi.org/10.1121/1.4877882.

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Strickland, Elizabeth A., Hayley Morris, Miranda Skaggs, William Salloom, and Alexis Holt. "Behavioral measures of cochlear gain reduction and gain reduction in with normal hearing or minimal cochlear hearing loss." Journal of the Acoustical Society of America 143, no. 3 (March 2018): 1964. http://dx.doi.org/10.1121/1.5036459.

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Fletcher, Mark, Jessica de Boer, and Katrin Krumbholz. "Does reduction in cochlear gain explain the overshoot effect?" Journal of the Acoustical Society of America 129, no. 4 (April 2011): 2593. http://dx.doi.org/10.1121/1.3588592.

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Strickland, Elizabeth A., Anna Hopkins, Andrea Rayner, William B. Salloom, Miranda Skaggs, Nicole Mielnicki, Hayley Morris, and Alexis Holt. "Examining potential sources of variability in behavioral measures of cochlear gain and gain reduction in listeners with normal hearing or minimal cochlear hearing loss." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A221—A222. http://dx.doi.org/10.1121/10.0011120.

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This study examined the relationship between clinical measures of auditory function and psychoacoustic measures related to cochlear function. Listeners’ audiometric thresholds for long tones ranged from well within the clinically normal range to just above this range. Where thresholds were elevated, other clinical tests were consistent with a cochlear origin. Because the medial olivocochlear reflex decreases cochlear gain in response to sound, measures were made with short stimuli. Signal frequencies were from 1 to 8 kHz. One point on the lower leg of the input/output function was measured by finding threshold masker level for a masker almost one octave below the signal frequency needed to mask a signal at 5 dB SL. Gain reduction was estimated by presenting a pink broadband noise precursor before the signal and masker and measuring the change in signal threshold as a function of precursor level. In a previous presentation, it was shown that the estimate of gain reduction decreased as quiet threshold increased, but was not solely determined by the amount of gain. In this presentation, the relationship between gain reduction and clinical otoacoustic emission and middle-ear muscle reflex measurements was examined to determine whether these explained some of the variability. [Work supported by NIH (NIDCD) R01 DC008327 (EAS) and NIH(NIDCD) T32 DC016853 (WBS).]

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Strickland, Elizabeth A., Alexis Holt, and Hayley Morris. "Cochlear gain reduction in listeners with borderline normal quiet thresholds." Journal of the Acoustical Society of America 141, no. 5 (May 2017): 3897. http://dx.doi.org/10.1121/1.4988759.

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Strickland, Elizabeth A., Miranda Skaggs, Anna Hopkins, Nicole Mielnicki, William B. Salloom, Hayley Morris, and Alexis Holt. "A summary of behavioral measures of cochlear gain and gain reduction in listeners with normal hearing or minimal cochlear hearing loss." Journal of the Acoustical Society of America 149, no. 4 (April 2021): A106. http://dx.doi.org/10.1121/10.0004659.

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Strickland, Elizabeth A., Miranda Skaggs, Nicole Mielnicki, William Salloom, Hayley Morris, and Alexis Holt. "Further analysis of behavioral measures of cochlear gain and gain reduction in listeners with normal hearing or minimal cochlear hearing loss." Journal of the Acoustical Society of America 145, no. 3 (March 2019): 1878. http://dx.doi.org/10.1121/1.5101797.

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Kressner, Abigail A., Tobias May, and Torsten Dau. "Effect of Noise Reduction Gain Errors on Simulated Cochlear Implant Speech Intelligibility." Trends in Hearing 23 (January 2019): 233121651982593. http://dx.doi.org/10.1177/2331216519825930.

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It has been suggested that the most important factor for obtaining high speech intelligibility in noise with cochlear implant (CI) recipients is to preserve the low-frequency amplitude modulations of speech across time and frequency by, for example, minimizing the amount of noise in the gaps between speech segments. In contrast, it has also been argued that the transient parts of the speech signal, such as speech onsets, provide the most important information for speech intelligibility. The present study investigated the relative impact of these two factors on the potential benefit of noise reduction for CI recipients by systematically introducing noise estimation errors within speech segments, speech gaps, and the transitions between them. The introduction of these noise estimation errors directly induces errors in the noise reduction gains within each of these regions. Speech intelligibility in both stationary and modulated noise was then measured using a CI simulation tested on normal-hearing listeners. The results suggest that minimizing noise in the speech gaps can improve intelligibility, at least in modulated noise. However, significantly larger improvements were obtained when both the noise in the gaps was minimized and the speech transients were preserved. These results imply that the ability to identify the boundaries between speech segments and speech gaps may be one of the most important factors for a noise reduction algorithm because knowing the boundaries makes it possible to minimize the noise in the gaps as well as enhance the low-frequency amplitude modulations of the speech.

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DeRoy Milvae, Kristina, and Elizabeth A. Strickland. "Psychoacoustic measurements of ipsilateral cochlear gain reduction as a function of signal frequency." Journal of the Acoustical Society of America 143, no. 5 (May 2018): 3114–25. http://dx.doi.org/10.1121/1.5038254.

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Zheng, Wenwen, Wei Cao, Shanwen Chen, Yifan Li, Yang Wang, Kun Yao, and Jianxin Qiu. "Change in Health-Related Quality of Life in Cochlear Implant Recipients in China." Journal of Healthcare Engineering 2022 (March 26, 2022): 1–5. http://dx.doi.org/10.1155/2022/1770580.

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Objective. The objective is to assess the benefit of cochlear implants in health-related quality of life among postlingually deaf adults in China. Methods. Seventy-one postlingually deaf adult cochlear implant users in one cochlear implant center in China participated in this study. The HUI3 questionnaire as a measurement evaluated their quality of life. A cross-sectional analysis was conducted. Results. Cochlear implant had made statistically significant improvements in quality of life among postlingually deaf adults. The HUI3 scores were significantly better in four attributes (hearing, speech, emotion, and pain) after a cochlear implant. A positive correlation between change in hearing and improvement in emotion was significant. The change in pain and improvement in emotion also had a positive correlation. The duration of HA and CI use had no impact on the gain in HUI3 scores, and the baseline of hearing and emotion state had an influence on HUI3 gain. Conclusion. This study found cochlear implant users had a greatly improved hearing, speech, emotion, and pain, which made statistically significant improvement in quality of life among postlingually deaf adults. There was a statistically significant association between the change of emotion state and improvement in hearing level. We also found a statistically significant correlation between the reduction of feeling in pain and improvement in emotion. The change of quality of life seemed to be influenced by the primary state of emotion and hearing. We believe the measurement HUI3 is suitable for these patients in China.

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Mauger, Stefan J., Pam W. Dawson, and Adam A. Hersbach. "Perceptually optimized gain function for cochlear implant signal-to-noise ratio based noise reduction." Journal of the Acoustical Society of America 131, no. 1 (January 2012): 327–36. http://dx.doi.org/10.1121/1.3665990.

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Roverud, Elin, and Elizabeth A. Strickland. "The time course of cochlear gain reduction measured using a more efficient psychophysical technique." Journal of the Acoustical Society of America 128, no. 3 (2010): 1203. http://dx.doi.org/10.1121/1.3473695.

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Marchetta, Philine, Daria Savitska, Angelika Kübler, Giulia Asola, Marie Manthey, Dorit Möhrle, Thomas Schimmang, Lukas Rüttiger, Marlies Knipper, and Wibke Singer. "Age-Dependent Auditory Processing Deficits after Cochlear Synaptopathy Depend on Auditory Nerve Latency and the Ability of the Brain to Recruit LTP/BDNF." Brain Sciences 10, no. 10 (October 6, 2020): 710. http://dx.doi.org/10.3390/brainsci10100710.

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Age-related decoupling of auditory nerve fibers from hair cells (cochlear synaptopathy) has been linked to temporal processing deficits and impaired speech recognition performance. The link between both is elusive. We have previously demonstrated that cochlear synaptopathy, if centrally compensated through enhanced input/output function (neural gain), can prevent age-dependent temporal discrimination loss. It was also found that central neural gain after acoustic trauma was linked to hippocampal long-term potentiation (LTP) and upregulation of brain-derived neurotrophic factor (BDNF). Using middle-aged and old BDNF-live-exon-visualization (BLEV) reporter mice we analyzed the specific recruitment of LTP and the activity-dependent usage of Bdnf exon-IV and -VI promoters relative to cochlear synaptopathy and central (temporal) processing. For both groups, specimens with higher or lower ability to centrally compensate diminished auditory nerve activity were found. Strikingly, low compensating mouse groups differed from high compensators by prolonged auditory nerve latency. Moreover, low compensators exhibited attenuated responses to amplitude-modulated tones, and a reduction of hippocampal LTP and Bdnf transcript levels in comparison to high compensators. These results suggest that latency of auditory nerve processing, recruitment of hippocampal LTP, and Bdnf transcription, are key factors for age-dependent auditory processing deficits, rather than cochlear synaptopathy or aging per se.

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de Boer, Jessica, A. Roger D. Thornton, and Katrin Krumbholz. "What is the role of the medial olivocochlear system in speech-in-noise processing?" Journal of Neurophysiology 107, no. 5 (March 1, 2012): 1301–12. http://dx.doi.org/10.1152/jn.00222.2011.

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The medial olivocochlear (MOC) bundle reduces the gain of the cochlear amplifier through reflexive activation by sound. Physiological results indicate that MOC-induced reduction in cochlear gain can enhance the response to signals when presented in masking noise. Some previous studies suggest that this “antimasking” effect of the MOC system plays a role in speech-in-noise perception. The present study set out to reinvestigate this hypothesis by correlating measures of MOC activity and speech-in-noise processing across a group of normal-hearing participants. MOC activity was measured using contralateral suppression of otoacoustic emissions (OAEs), and speech-in-noise processing was measured by measuring the effect of noise masking on performance in a consonant-vowel (CV) discrimination task and on auditory brain stem responses evoked by a CV syllable. Whereas there was a significant correlation between OAE suppression and both measures of speech-in-noise processing, the direction of this correlation was opposite to that predicted by the antimasking hypothesis, in that individuals with stronger OAE suppression tended to show greater noise-masking effects on CV processing. The current results indicate that reflexive MOC activation is not always beneficial to speech-in-noise processing. We propose an alternative to the antimasking hypothesis, whereby the MOC system benefits speech-in-noise processing through dynamic (e.g., attention- and experience-dependent), rather than reflexive, control of cochlear gain.

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Noreña, Arnaud J. "Revisiting the Cochlear and Central Mechanisms of Tinnitus and Therapeutic Approaches." Audiology and Neurotology 20, Suppl. 1 (2015): 53–59. http://dx.doi.org/10.1159/000380749.

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This short review aims at revisiting some of the putative mechanisms of tinnitus. Cochlear-type tinnitus is suggested to result from aberrant activity generated before or at the cochlear nerve level. It is proposed that outer hair cells, through their role in regulating the endocochlear potential, can contribute to the enhancement of cochlear spontaneous activity. This hypothesis is attractive as it provides a possible explanation for cochlear tinnitus of different aetiologies, such as tinnitus produced by acute noise trauma, intense low-frequency sounds, middle-ear dysfunction or temporomandibular joint disorders. Other mechanisms, namely an excitatory drift in the operating point of the inner hair cells and activation of NMDA receptors, are also briefly reported. Central-type tinnitus is supposed to result from aberrant activity generated in auditory centres, i.e. in these patients, the tinnitus-related activity does not pre-exist in the cochlear nerve. A reduction in cochlear activity due to hearing loss is suggested to produce tinnitus-related plastic changes, namely cortical reorganisation, thalamic neuron hyperpolarisation, facilitation of non-auditory inputs and/or increase in central gain. These central changes can be associated with abnormal patterns of spontaneous activity in the auditory pathway, i.e. hyperactivity, hypersynchrony and/or oscillating activity. Therapeutic approaches aimed at reducing cochlear activity and/or tinnitus-related central changes are discussed.

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Messersmith, Jessica J., Lindsey E. Jorgensen, and Jessica A. Hagg. "Reduction in High-Frequency Hearing Aid Gain Can Improve Performance in Patients With Contralateral Cochlear Implant: A Pilot Study." American Journal of Audiology 24, no. 4 (December 2015): 462–68. http://dx.doi.org/10.1044/2015_aja-15-0045.

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Purpose The purpose of this study was to determine whether an alternate fitting strategy, specifically adjustment to gains in a hearing aid (HA), would improve performance in patients who experienced poorer performance in the bimodal condition when the HA was fit to traditional targets. Method This study was a retrospective chart review from a local clinic population seen during a 6-month period. Participants included 6 users of bimodal stimulation. Two performed poorer in the cochlear implant (CI) + HA condition than in the CI-only condition. One individual performed higher in the bimodal condition, but the overall performance was low. Three age range–matched users whose performance increased when the HA was used in conjunction with a CI were also included. The HA gain was reduced beyond 2000 Hz. Speech perception scores were obtained pre- and postmodification to the HA fitting. Results All listeners whose HA was programmed using the modified approach demonstrated improved speech perception scores with the modified HA fit in the bimodal condition when compared with the traditional HA fit in the bimodal condition. Conclusion Modifications to gains above 2000 Hz in the HA may improve performance for bimodal listeners who perform more poorly in the bimodal condition when the HA is fit to traditional targets.

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Liu, Yi-Wen, Kuang-Yi Lin, and Yong-Zing Chen. "Frequency-domain analysis of cochlear gain reduction due to disruptions in the outer hair cell feedback loop." Journal of the Acoustical Society of America 133, no. 5 (May 2013): 3427. http://dx.doi.org/10.1121/1.4806028.

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Bhagat, Shaum P., and Chelsea Kilgore. "Efferent-mediated reduction in cochlear gain does not alter tuning estimates from stimulus-frequency otoacoustic emission group delays." Neuroscience Letters 559 (January 2014): 132–35. http://dx.doi.org/10.1016/j.neulet.2013.11.059.

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DeRoy Milvae, Kristina, Joshua M. Alexander, and Elizabeth A. Strickland. "The relationship between ipsilateral cochlear gain reduction and speech-in-noise recognition at positive and negative signal-to-noise ratios." Journal of the Acoustical Society of America 149, no. 5 (May 2021): 3449–61. http://dx.doi.org/10.1121/10.0003964.

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Abel, Cornelius, and Manfred Kössl. "Sensitive Response to Low-Frequency Cochlear Distortion Products in the Auditory Midbrain." Journal of Neurophysiology 101, no. 3 (March 2009): 1560–74. http://dx.doi.org/10.1152/jn.90805.2008.

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During auditory stimulation with several frequency components, distortion products (DPs) are generated as byproduct of nonlinear cochlear amplification. After generated, DP energy is reemitted into the ear channel where it can be measured as DP otoacoustic emission (DPOAE), and it also induces an excitatory response at cochlear places related to the DP frequencies. We measured responses of 91 inferior colliculus (IC) neurons in the gerbil during two-tone stimulation with frequencies well above the unit's receptive field but adequate to generate a distinct distortion product (f2-f1 or 2f1-f2) at the unit's characteristic frequency (CF). Neuronal responses to DPs could be accounted for by the simultaneously measured DPOAEs for DP frequencies >1.3 kHz. For DP frequencies <1.3 kHz ( n = 25), there was a discrepancy between intracochlear DP magnitude and DPOAE level, and most neurons responded as if the intracochlear DP level was significantly higher than the DPOAE level in the ear channel. In 12% of those low-frequency neurons, responses to the DPs could be elicited even if the stimulus tone levels were below the threshold level of the neuron at CF. High intracochlear f2-f1 and 2f1-f2 DP-levels were verified by cancellation of the neuronal DP response with a third phase-adjusted tone stimulus at the DP frequency. A frequency-specific reduction of middle ear gain at low frequencies is possibly involved in the reduction of DPOAE level. The results indicate that pitch-related properties of complex stimuli may be produced partially by high intracochlear f2-f1 distortion levels.

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Milvae, Kristina D., Joshua M. Alexander, and Elizabeth A. Strickland. "Investigation of the relationship between cochlear gain reduction and speech-in-noise performance at positive and negative signal-to-noise ratios." Journal of the Acoustical Society of America 139, no. 4 (April 2016): 1987. http://dx.doi.org/10.1121/1.4949804.

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Langner, Florian, Andreas Büchner, and Waldo Nogueira. "Evaluation of an Adaptive Dynamic Compensation System in Cochlear Implant Listeners." Trends in Hearing 24 (January 2020): 233121652097034. http://dx.doi.org/10.1177/2331216520970349.

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Cochlear implant (CI) sound processing typically uses a front-end automatic gain control (AGC), reducing the acoustic dynamic range (DR) to control the output level and protect the signal processing against large amplitude changes. It can also introduce distortions into the signal and does not allow a direct mapping between acoustic input and electric output. For speech in noise, a reduction in DR can result in lower speech intelligibility due to compressed modulations of speech. This study proposes to implement a CI signal processing scheme consisting of a full acoustic DR with adaptive properties to improve the signal-to-noise ratio and overall speech intelligibility. Measurements based on the Short-Time Objective Intelligibility measure and an electrodogram analysis, as well as behavioral tests in up to 10 CI users, were used to compare performance with a single-channel, dual-loop, front-end AGC and with an adaptive back-end multiband dynamic compensation system (Voice Guard [VG]). Speech intelligibility in quiet and at a +10 dB signal-to-noise ratio was assessed with the Hochmair–Schulz–Moser sentence test. A logatome discrimination task with different consonants was performed in quiet. Speech intelligibility was significantly higher in quiet for VG than for AGC, but intelligibility was similar in noise. Participants obtained significantly better scores with VG than AGC in the logatome discrimination task. The objective measurements predicted significantly better performance estimates for VG. Overall, a dynamic compensation system can outperform a single-stage compression (AGC + linear compression) for speech perception in quiet.

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Ausili, Sebastian A., Bradford Backus, Martijn J. H. Agterberg, A. John van Opstal, and Marc M. van Wanrooij. "Sound Localization in Real-Time Vocoded Cochlear-Implant Simulations With Normal-Hearing Listeners." Trends in Hearing 23 (January 2019): 233121651984733. http://dx.doi.org/10.1177/2331216519847332.

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Bilateral cochlear-implant (CI) users and single-sided deaf listeners with a CI are less effective at localizing sounds than normal-hearing (NH) listeners. This performance gap is due to the degradation of binaural and monaural sound localization cues, caused by a combination of device-related and patient-related issues. In this study, we targeted the device-related issues by measuring sound localization performance of 11 NH listeners, listening to free-field stimuli processed by a real-time CI vocoder. The use of a real-time vocoder is a new approach, which enables testing in a free-field environment. For the NH listening condition, all listeners accurately and precisely localized sounds according to a linear stimulus–response relationship with an optimal gain and a minimal bias both in the azimuth and in the elevation directions. In contrast, when listening with bilateral real-time vocoders, listeners tended to orient either to the left or to the right in azimuth and were unable to determine sound source elevation. When listening with an NH ear and a unilateral vocoder, localization was impoverished on the vocoder side but improved toward the NH side. Localization performance was also reflected by systematic variations in reaction times across listening conditions. We conclude that perturbation of interaural temporal cues, reduction of interaural level cues, and removal of spectral pinna cues by the vocoder impairs sound localization. Listeners seem to ignore cues that were made unreliable by the vocoder, leading to acute reweighting of available localization cues. We discuss how current CI processors prevent CI users from localizing sounds in everyday environments.

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Dreisbach, Laura E., Marjorie R. Leek, and Jennifer J. Lentz. "Perception of Spectral Contrast by Hearing-Impaired Listeners." Journal of Speech, Language, and Hearing Research 48, no. 4 (August 2005): 910–21. http://dx.doi.org/10.1044/1092-4388(2005/063).

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The ability to discriminate the spectral shapes of complex sounds is critical to accurate speech perception. Part of the difficulty experienced by listeners with hearing loss in understanding speech sounds in noise may be related to a smearing of the internal representation of the spectral peaks and valleys because of the loss of sensitivity and an accompanying reduction in frequency resolution. This study examined the discrimination by hearing-impaired listeners of highly similar harmonic complexes with a single spectral peak located in 1 of 3 frequency regions. The minimum level difference between peak and background harmonics required to discriminate a small change in the spectral center of the peak was measured for peaks located near 2, 3, or 4 kHz. Component phases were selected according to an algorithm thought to produce either highly modulated (positive Schroeder) or very flat (negative Schroeder) internal waveform envelopes in the cochlea. The mean amplitude difference between a spectral peak and the background components required for discrimination of pairs of harmonic complexes (spectral contrast threshold) was from 4 to 19 dB greater for listeners with hearing impairment than for a control group of listeners with normal hearing. In normal-hearing listeners, improvements in threshold were seen with increasing stimulus level, and there was a strong effect of stimulus phase, as the positive Schroeder stimuli always produced lower thresholds than the negative Schroeder stimuli. The listeners with hearing loss showed no consistent spectral contrast effects due to stimulus phase and also showed little improvement with increasing stimulus level, once their sensitivity loss was overcome. The lack of phase and level effects may be a result of the more linear processing occurring in impaired ears, producing poorer-than-normal frequency resolution, a loss of gain for low amplitudes, and an altered cochlear phase characteristic in regions of damage.

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Vollmer, Maike, and Ralph E. Beitel. "Behavioral training restores temporal processing in auditory cortex of long-deaf cats." Journal of Neurophysiology 106, no. 5 (November 2011): 2423–36. http://dx.doi.org/10.1152/jn.00565.2011.

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Temporal auditory processing is poor in prelingually hearing-impaired patients fitted with cochlear prostheses as adults. In an animal model of prelingual long-term deafness, we investigated the effects of behavioral training on temporal processing in the adult primary auditory cortex (AI). Neuronal responses to pulse trains of increasing frequencies were recorded in three groups of neonatally deafened cats that received a cochlear prosthesis after >3 yr of deafness: 1) acutely implanted animals that received no electric stimulation before study, 2) animals that received chronic-passive stimulation for several weeks to months before study, and 3) animals that received chronic-passive stimulation and additional behavioral training (signal detection). A fourth group of normal adult cats that was deafened acutely and implanted served as controls. The neuronal temporal response parameters of interest included the stimulus rate that evoked the maximum number of phase-locked spikes [best repetition rate (BRR)], the stimulus rate that produced 50% of the spike count at BRR (cutoff rate), the peak-response latency, and the first spike latency and timing-jitter. All long-deaf animals demonstrated a severe reduction in spiral ganglion cell density (mean, <6% of normal). Long-term deafness resulted in a significantly reduced temporal following capacity and spike-timing precision of cortical neurons in all parameters tested. Neurons in deaf animals that received only chronic-passive stimulation showed a gain in BRR but otherwise were similar to deaf cats that received no stimulation. In contrast, training with behaviorally relevant stimulation significantly enhanced all temporal processing parameters to normal levels with the exception of minimum latencies. These results demonstrate the high efficacy of learning-based remodeling of fundamental timing properties in cortical processing even in the adult, long-deaf auditory system, suggesting rehabilitative strategies for patients with long-term hearing loss.

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Kalpana, G., Raja Krishnamoorthy, and P. T. Kalaivaani. "Design and implementation of low-power CMOS biosignal amplifier for active electrode in biomedical application using subthreshold biasing strategy." International Journal of Wavelets, Multiresolution and Information Processing 18, no. 01 (May 29, 2019): 1941017. http://dx.doi.org/10.1142/s0219691319410170.

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Active Electrodes (AEs) are electrodes which have integrated bio-amplifier circuitry and are known to be less susceptible to motion artifacts and environmental interference. In this work, a low-power and high-input impedance amplifier for active electrode application is implemented based on subthreshold biasing strategies. In this proposed Application Specific Integrated Circuit (ASIC) device was versatile and numerical to achieve a high degree of programmability. It could be adapted to any other external part of one cochlear prosthesis, the sound analyzer that could be driven by a Digital Signal Processor (DSP). This research work also discusses the measurement of the electrode-skin impedance mismatch between two electrodes while concurrently measuring a bioelectrical signal without degradation of the performance of the amplifier, the efficient, noise-optimized analysis of bioelectrical signals utilizing two-wired active buffer electrodes. The reduction of power-line interference when using amplifying electrodes employing autonomous adaption of the gain of the subsequent differential amplification. The amplifier’s features include offset compensation, Common Mode Rejection Ratio (CMRR) improvement in software and a bandwidth extending down to DC. The proposed active electrode amplifier is designed using 90 nm CMOS technology. Simulation results exhibit up to the change in noise immunity and lessening in power utilization contrasted with the traditional bio-amplifier design at a similar delay.

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Rasetshwane, Daniel M., David A. Raybine, Judy G. Kopun, Michael P. Gorga, and Stephen T. Neely. "Influence of Instantaneous Compression on Recognition of Speech in Noise with Temporal Dips." Journal of the American Academy of Audiology 30, no. 01 (January 2019): 016–30. http://dx.doi.org/10.3766/jaaa.16165.

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AbstractIn listening environments with background noise that fluctuates in level, listeners with normal hearing can “glimpse” speech during dips in the noise, resulting in better speech recognition in fluctuating noise than in steady noise at the same overall level (referred to as masking release). Listeners with sensorineural hearing loss show less masking release. Amplification can improve masking release but not to the same extent that it does for listeners with normal hearing.The purpose of this study was to compare masking release for listeners with sensorineural hearing loss obtained with an experimental hearing-aid signal-processing algorithm with instantaneous compression (referred to as a suppression hearing aid, SHA) to masking release obtained with fast compression. The suppression hearing aid mimics effects of normal cochlear suppression, i.e., the reduction in the response to one sound by the simultaneous presentation of another sound.A within-participant design with repeated measures across test conditions was used.Participants included 29 adults with mild-to-moderate sensorineural hearing loss and 21 adults with normal hearing.Participants with sensorineural hearing loss were fitted with simulators for SHA and a generic hearing aid (GHA) with fast (but not instantaneous) compression (5 ms attack and 50 ms release times) and no suppression. Gain was prescribed using either an experimental method based on categorical loudness scaling (CLS) or the Desired Sensation Level (DSL) algorithm version 5a, resulting in a total of four processing conditions: CLS-GHA, CLS-SHA, DSL-GHA, and DSL-SHA.All participants listened to consonant-vowel-consonant nonwords in the presence of temporally-modulated and steady noise. An adaptive-tracking procedure was used to determine the signal-to-noise ratio required to obtain 29% and 71% correct. Measurements were made with amplification for participants with sensorineural hearing loss and without amplification for participants with normal hearing.Repeated-measures analysis of variance was used to determine the influence of within-participant factors of noise type and, for participants with sensorineural hearing loss, processing condition on masking release. Pearson correlational analysis was used to assess the effect of age on masking release for participants with sensorineural hearing loss.Statistically significant masking release was observed for listeners with sensorineural hearing loss for 29% correct, but not for 71% correct. However, the amount of masking release was less than masking release for participants with normal hearing. There were no significant differences among the amplification conditions for participants with sensorineural hearing loss.The results suggest that amplification with either instantaneous or fast compression resulted in similar masking release for listeners with sensorineural hearing loss. However, the masking release was less for participants with hearing loss than it was for those with normal hearing.

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Mo, Jonathan, Nicole T. Jiam, Mickael L. D. Deroche, Patpong Jiradejvong, and Charles J. Limb. "Effect of Frequency Response Manipulations on Musical Sound Quality for Cochlear Implant Users." Trends in Hearing 26 (January 2022): 233121652211200. http://dx.doi.org/10.1177/23312165221120017.

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Cochlear implant (CI) users commonly report degraded musical sound quality. To improve CI-mediated music perception and enjoyment, we must understand factors that affect sound quality. In the present study, we utilize frequency response manipulation (FRM), a process that adjusts the energies of frequency bands within an audio signal, to determine its impact on CI-user sound quality assessments of musical stimuli. Thirty-three adult CI users completed an online study and listened to FRM-altered clips derived from the top songs in Billboard magazine. Participants assessed sound quality using the MUltiple Stimulus with Hidden Reference and Anchor for CI users (CI-MUSHRA) rating scale. FRM affected sound quality ratings (SQR). Specifically, increasing the gain for low and mid-range frequencies led to higher quality ratings than reducing them. In contrast, manipulating the gain for high frequencies (those above 2 kHz) had no impact. Participants with musical training were more sensitive to FRM than non-musically trained participants and demonstrated preference for gain increases over reductions. These findings suggest that, even among CI users, past musical training provides listeners with subtleties in musical appraisal, even though their hearing is now mediated electrically and bears little resemblance to their musical experience prior to implantation. Increased gain below 2 kHz may lead to higher sound quality than for equivalent reductions, perhaps because it offers greater access to lyrics in songs or because it provides more salient beat sensations.

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Dougherty, Kelsey, Alexandra Hustedt-Mai, Anna Hagedorn, and Hari Bharadwaj. "Central gain in aging, tinnitus, and temporary hearing loss." Journal of the Acoustical Society of America 150, no. 4 (October 2021): A341. http://dx.doi.org/10.1121/10.0008520.

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The nervous system adapts in many ways to changes in the statistics of the inputs it receives. An example of such plasticity observed in animal models is that central auditory neurons tend to retain their driven firing rate outputs despite reductions in cochlear input due to hearing loss or deafferentation. The perceptual consequences of such “central gain” are unknown; pathological versions of such gain are often hypothesized to underlie tinnitus and hyperacusis. To investigate central gain in humans, we designed an electroencephalogram (EEG)-based paradigm that concurrently elicits robust separable responses from different levels of the auditory pathway. Using this measure, we find that cortical responses are relatively invariant despite a large monotonic decrease in auditory nerve responses with age, and that this central gain is also associated with perceptual deficits in co-modulation processing. We then applied the same measures to a cohort of individuals with persistent tinnitus and to a third cohort where a week-long monaural conductive hearing loss was induced using silicone earplugs. Overall, our results suggest that central gain is ubiquitous in response to reduced peripheral input and may affect auditory scene analysis, but does not in itself account for tinnitus perception.

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Bramhall, Naomi F., Christopher E. Niemczak, Sean D. Kampel, Curtis J. Billings, and Garnett P. McMillan. "Evoked Potentials Reveal Noise Exposure–Related Central Auditory Changes Despite Normal Audiograms." American Journal of Audiology 29, no. 2 (June 8, 2020): 152–64. http://dx.doi.org/10.1044/2019_aja-19-00060.

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Purpose Complaints of auditory perceptual deficits, such as tinnitus and difficulty understanding speech in background noise, among individuals with clinically normal audiograms present a perplexing problem for audiologists. One potential explanation for these “hidden” auditory deficits is loss of the synaptic connections between the inner hair cells and their afferent auditory nerve fiber targets, a condition that has been termed cochlear synaptopathy . In animal models, cochlear synaptopathy can occur due to aging or exposure to noise or ototoxic drugs and is associated with reduced auditory brainstem response (ABR) wave I amplitudes. Decreased ABR wave I amplitudes have been demonstrated among young military Veterans and non-Veterans with a history of firearm use, suggesting that humans may also experience noise-induced synaptopathy. However, the downstream consequences of synaptopathy are unclear. Method To investigate how noise-induced reductions in wave I amplitude impact the central auditory system, the ABR, the middle latency response (MLR), and the late latency response (LLR) were measured in 65 young Veterans and non-Veterans with normal audiograms. Results In response to a click stimulus, the MLR was weaker for Veterans compared to non-Veterans, but the LLR was not reduced. In addition, low ABR wave I amplitudes were associated with a reduced MLR, but with an increased LLR. Notably, Veterans reporting tinnitus showed the largest mean LLRs. Conclusions These findings indicate that decreased peripheral auditory input leads to compensatory gain in the central auditory system, even among individuals with normal audiograms, and may impact auditory perception. This pattern of reduced MLR, but not LLR, was observed among Veterans even after statistical adjustment for sex and distortion product otoacoustic emission differences, suggesting that synaptic loss plays a role in the observed central gain. Supplemental Material https://doi.org/10.23641/asha.11977854

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DeRoy Milvae, Kristina, and Elizabeth A. Strickland. "Behavioral Measures of Cochlear Gain Reduction Depend on Precursor Frequency, Bandwidth, and Level." Frontiers in Neuroscience 15 (October 4, 2021). http://dx.doi.org/10.3389/fnins.2021.716689.

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Sensory systems adjust to the environment to maintain sensitivity to change. In the auditory system, the medial olivocochlear reflex (MOCR) is a known physiological mechanism capable of such adjustment. The MOCR provides efferent feedback between the brainstem and cochlea, reducing cochlear gain in response to sound. The perceptual effects of the MOCR are not well understood, such as how gain reduction depends on elicitor characteristics in human listeners. Physiological and behavioral data suggest that ipsilateral MOCR tuning is only slightly broader than it is for afferent fibers, and that the fibers feed back to the frequency region of the cochlea that stimulated them. However, some otoacoustic emission (OAE) data suggest that noise is a more effective elicitor than would be consistent with sharp tuning, and that a broad region of the cochlea may be involved in elicitation. If the elicitor is processed in a cochlear channel centered at the signal frequency, the growth of gain reduction with elicitor level would be expected to depend on the frequency content of the elicitor. In the current study, the effects of the frequency content and level of a preceding sound (called a precursor) on signal threshold was examined. The results show that signal threshold increased with increasing precursor level at a shallower slope for a tonal precursor at the signal frequency than for a tonal precursor nearly an octave below the signal frequency. A broadband noise was only slightly more effective than a tone at the signal frequency, with a relatively shallow slope similar to that of the tonal precursor at the signal frequency. Overall, these results suggest that the excitation at the signal cochlear place, regardless of elicitor frequency, determines the magnitude of ipsilateral cochlear gain reduction, and that it increases with elicitor level.

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Xia, Anping, Tomokatsu Udagawa, Patricia M. Quiñones, Patrick J. Atkinson, Brian E. Applegate, Alan G. Cheng, and John S. Oghalai. "The impact of targeted ablation of one row of outer hair cells and Deiters' cells on cochlear amplification." Journal of Neurophysiology, October 19, 2022. http://dx.doi.org/10.1152/jn.00501.2021.

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The mammalian cochlea contains three rows of outer hair cells (OHCs) that amplify the basilar membrane traveling wave with high gain and exquisite tuning. The pattern of OHC loss caused by typical methods of producing hearing loss in animal models (noise, ototoxic exposure, or aging) is variable and not consistent along the length of the cochlea. Thus, it is difficult to use these approaches to understand how forces from multiple OHCs summate to create normal cochlear amplification. Here, we selectively removed the third row of OHCs and Deiters' cells in adult mice and measured cochlear amplification. In the mature cochlear epithelia, expression of the Wnt target gene Lgr5 is restricted to the third row of Deiters' cells, the supporting cells directly underneath the OHCs. Diphtheria toxin administration to Lgr5DTR-EGFP/+ mice selectively ablated the third row of Deiters' cells and the third row of OHCs. Basilar membrane vibration in vivo demonstrated disproportionately lower reduction in cochlear amplification by about 13.5 dB. On a linear scale, this means that the 33% reduction in OHC number led to a 79% reduction in gain. Thus, these experimental data describe the impact of reducing the force of cochlear amplification by a specific amount. Furthermore, these data argue that because OHC forces progressively and sequentially amplify the traveling wave as it travels to its peak, the loss of even a relatively small number of OHCs, when evenly distributed longitudinally, will cause a substantial reduction in cochlear amplification.

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Salvi, Richard, Kelly Radziwon, Senthilvelan Manohar, Ben Auerbach, Dalian Ding, Xiaopeng Liu, Condon Lau, Yu-Chen Chen, and Guang-Di Chen. "Review: Neural Mechanisms of Tinnitus and Hyperacusis in Acute Drug-Induced Ototoxicity." American Journal of Audiology, January 19, 2021, 1–15. http://dx.doi.org/10.1044/2020_aja-20-00023.

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Purpose Tinnitus and hyperacusis are debilitating conditions often associated with age-, noise-, and drug-induced hearing loss. Because of their subjective nature, the neural mechanisms that give rise to tinnitus and hyperacusis are poorly understood. Over the past few decades, considerable progress has been made in deciphering the biological bases for these disorders using animal models. Method Important advances in understanding the biological bases of tinnitus and hyperacusis have come from studies in which tinnitus and hyperacusis are consistently induced with a high dose of salicylate, the active ingredient in aspirin. Results Salicylate induced a transient hearing loss characterized by a reduction in otoacoustic emissions, a moderate cochlear threshold shift, and a large reduction in the neural output of the cochlea. As the weak cochlear neural signals were relayed up the auditory pathway, they were progressively amplified so that the suprathreshold neural responses in the auditory cortex were much larger than normal. Excessive central gain (neural amplification), presumably resulting from diminished inhibition, is believed to contribute to hyperacusis and tinnitus. Salicylate also increased corticosterone stress hormone levels. Functional imaging studies indicated that salicylate increased spontaneous activity and enhanced functional connectivity between structures in the central auditory pathway and regions of the brain associated with arousal (reticular formation), emotion (amygdala), memory/spatial navigation (hippocampus), motor planning (cerebellum), and motor control (caudate/putamen). Conclusion These results suggest that tinnitus and hyperacusis arise from aberrant neural signaling in a complex neural network that includes both auditory and nonauditory structures.

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Fuentealba Bassaletti, Constanza, Babette F. van Esch, Jeroen J. Briaire, Peter Paul G. van Benthem, Erik F. Hensen, and Johan H. M. Frijns. "Saccades Matter: Reduced Need for Caloric Testing of Cochlear Implant Candidates by Joint Analysis of v-HIT Gain and Corrective Saccades." Frontiers in Neurology 12 (June 28, 2021). http://dx.doi.org/10.3389/fneur.2021.676812.

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Objectives: Video head impulse test (v-HIT) is a quick, non-invasive and relatively cheap test to evaluate vestibular function compared to the caloric test. The latter is, however, needed to decide on the optimal side to perform cochlear implantation to avoid the risk on inducing a bilateral vestibular areflexia. This study evaluates the effectiveness of using the v-HIT to select cochlear implant (CI) candidates who require subsequent caloric testing before implantation, in that way reducing costs and patient burden at the same time.Study Design: Retrospective study using clinical data from 83 adult CI-candidates, between 2015 and 2020 at the Leiden University Medical Center.Materials and Methods: We used the v-HIT mean gain, MinGain_LR, the gain asymmetry (GA) and a newly defined parameter, MGS (Minimal Gain & Saccades) as different models to detect the group of patients that would need the caloric test to decide on the ear of implantation. The continuous model MGS was defined as the MinGain_LR, except for the cases with normal gain (both sides ≥0.8) where no corrective saccades were present. In the latter case MGS was defined to be 1.0 (the ideal gain value).Results: The receiver operating characteristics curve showed a very good diagnostic accuracy with and area under the curve (AUC) of 0.81 for the model MGS. The v-HIT mean gain, the minimal gain and GA had a lower diagnostic capacity with an AUC of 0.70, 0.72, and 0.73, respectively. Using MGS, caloric testing could be avoided in 38 cases (a reduction of 46%), with a test sensitivity of 0.9 (i.e., missing 3 of 28 cases).Conclusions: The newly developed model MGS balances the sensitivity and specificity of the v-HIT better than the more commonly evaluated parameters such as mean gain, MinGain_LR and GA. Therefore, taking the presence of corrective saccades into account in the evaluation of the v-HIT gain can considerably reduce the proportion of CI-candidates requiring additional caloric testing.

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Janky, Kristen L., Megan Thomas, Sarah Al-Salim, and Sara Robinson. "Does vestibular loss result in cognitive deficits in children with cochlear implants?" Journal of Vestibular Research, March 5, 2022, 1–16. http://dx.doi.org/10.3233/ves-201556.

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BACKGROUND: In adults, vestibular loss is associated with cognitive deficits; however, similar relationships have not been studied in children. OBJECTIVE: Evaluate the effect of vestibular loss on working memory and executive function in children with a cochlear implant (CCI) compared to children with normal hearing (CNH). METHODS: Vestibular evoked myogenic potential, video head impulse, rotary chair, and balance testing; and the following clinical measures: vision, hearing, speech perception, language, executive function, and working memory. RESULTS: Thirty-eight CNH and 37 CCI participated (26 with normal vestibular function, 5 with unilateral vestibular loss, 6 with bilateral vestibular loss). Children with vestibular loss demonstrated the poorest balance performance. There was no significant reduction in working memory or executive function performance for either CCI group with vestibular loss; however, multivariate regression analysis suggested balance performance was a significant predictor for several working memory subtests and video head impulse gain was a significant predictor for one executive function outcome. CONCLUSIONS: CCI with vestibular loss did not have significantly reduced working memory or executive function; however, balance performance was a significant predictor for several working memory subtests. Degree of hearing loss should be considered, and larger sample sizes are needed.

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Curthoys, Ian S., Leonardo Manzari, Jorge Rey-Martinez, Julia Dlugaiczyk, and Ann M. Burgess. "Enhanced Eye Velocity in Head Impulse Testing—A Possible Indicator of Endolymphatic Hydrops." Frontiers in Surgery 8 (May 7, 2021). http://dx.doi.org/10.3389/fsurg.2021.666390.

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Introduction: On video head impulse testing (vHIT) of semicircular canal function, some patients reliably show enhanced eye velocity and so VOR gains >1.0. Modeling and imaging indicate this could be due to endolymphatic hydrops. Oral glycerol reduces membranous labyrinth volume and reduces cochlear symptoms of hydrops, so we tested whether oral glycerol reduced the enhanced vHIT eye velocity.Study Design: Prospective clinical study and retrospective analysis of patient data.Methods: Patients with enhanced eye velocity during horizontal vHIT were enrolled (n = 9, 17 ears) and given orally 86% glycerol, 1.5 mL/kg of body weight, dissolved 1:1 in physiological saline. Horizontal vHIT testing was performed before glycerol intake (time 0), then at intervals of 1, 2, and 3 h after the oral glycerol intake. Control patients with enhanced eye velocity (n = 4, 6 ears) received water and were tested at the same intervals. To provide an objective index of enhanced eye velocity we used a measure of VOR gain which captures the enhanced eye velocity which is so clear on inspecting the eye velocity records. We call this measure the initial VOR gain and it is defined as: (the ratio of peak eye velocity to the value of head velocity at the time of peak eye velocity). The responses of other patients who showed enhanced eye velocity during routine clinical testing were analyzed to try to identify how the enhancement occurred.Results: We found that oral glycerol caused, on average, a significant reduction in the enhanced eye velocity response, whereas water caused no systematic change. The enhanced eye velocity during the head impulses is due in some patients to a compensatory saccade-like response during the increasing head velocity.Conclusion: The significant reduction in enhanced eye velocity during head impulse testing following oral glycerol is consistent with the hypothesis that the enhanced eye velocity in vHIT may be caused by endolymphatic hydrops.

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Smeal, Molly, Hillary Snapp, Sebastian Ausili, Meredith Holcomb, and Sandra Prentiss. "Effects of Bilateral Cochlear Implantation on Binaural Listening Tasks for Younger and Older Adults." Audiology and Neurotology, May 30, 2022, 1–11. http://dx.doi.org/10.1159/000523914.

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Purpose: This study investigated the objective and subjective benefit of a second cochlear implant (CI) on binaural listening tasks of speech understanding in noise and localization in younger and older adults. We aimed to determine if the aging population can utilize binaural cues and obtain comparable benefits from bilateral CI (BIL_CI) when compared to the younger population. Methods: Twenty-nine adults with severe to profound bilateral sensorineural hearing loss were included. Participants were evaluated in two conditions, better CI (BE_CI) alone and BIL_CI using AzBio and Bamford-Kowal-Bench (BKB) sentence in noise tests. Localization tasks were completed in the BIL_CI condition using a broadband stimulus, low-frequency stimuli, and high-frequency stimuli. A subjective questionnaire was administered to assess satisfaction with CI. Results: Older age was significantly associated with poorer performance on AzBio +5 dB signal-to-noise ratio (SNR) and BKB-speech in noise (SIN); however, improvements from BE_CI to BIL_CI were observed across all ages. In the AzBio +5 condition, nearly half of all participants achieved a significant improvement from BE_CI to BIL_CI with the majority of those occurring in patients younger than 65 years of age. Conversely, the majority of participants who achieved a significant improvement in BKB-SIN were adults >65 years of age. Years of BIL_CI experience and time between implants were not associated with performance. For localization, mean absolute error increased with age for low and high narrowband noise, but not for the broadband noise. Response gain was negatively correlated with age for all localization stimuli. Neither BIL_CI listening experience nor time between implants significantly impacted localization ability. Subjectively, participants report reduction in disability with the addition of the second CI. There is no observed relationship between age or speech recognition score and satisfaction with BIL_CI. Conclusion: Overall performance on binaural listening tasks was poorer in older adults than in younger adults. However, older adults were able to achieve significant benefit from the addition of a second CI, and performance on binaural tasks was not correlated with overall device satisfaction. The significance of the improvement was task and stimulus dependent but suggested a critical limit may exist for optimal performance on SIN tasks for CI users. Specifically, older adults require at least a +8 dB SNR to understand 50% of speech postoperatively; therefore, solely utilizing a fixed +5 dB SNR preoperatively to qualify CI candidates is not recommended as this test condition may introduce limitations in demonstrating CI benefit.

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Yoon, Yang-Soo, and Carrie Drew. "Effects of the intensified frequency and time ranges on consonant enhancement in bilateral cochlear implant and hearing aid users." Frontiers in Psychology 13 (August 16, 2022). http://dx.doi.org/10.3389/fpsyg.2022.918914.

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A previous study demonstrated that consonant recognition improved significantly in normal hearing listeners when useful frequency and time ranges were intensified by 6 dB. The goal of this study was to determine whether bilateral cochlear implant (BCI) and bilateral hearing aid (BHA) users experienced similar enhancement on consonant recognition with these intensified spectral and temporal cues in noise. In total, 10 BCI and 10 BHA users participated in a recognition test using 14 consonants. For each consonant, we used the frequency and time ranges that are critical for its recognition (called “target frequency and time range”), identified from normal hearing listeners. Then, a signal processing tool called the articulation-index gram (AI-Gram) was utilized to add a 6 dB gain to target frequency and time ranges. Consonant recognition was monaurally and binaurally measured under two signal processing conditions, unprocessed and intensified target frequency and time ranges at +5 and +10 dB signal-to-noise ratio and in quiet conditions. We focused on three comparisons between the BCI and BHA groups: (1) AI-Gram benefits (i.e., before and after intensifying target ranges by 6 dB), (2) enhancement in binaural benefits (better performance with bilateral devices compared to the better ear alone) via the AI-Gram processing, and (3) reduction in binaural interferences (poorer performance with bilateral devices compared to the better ear alone) via the AI-Gram processing. The results showed that the mean AI-Gram benefit was significantly improved for the BCI (max 5.9%) and BHA (max 5.2%) groups. However, the mean binaural benefit was not improved after AI-Gram processing. Individual data showed wide ranges of the AI-Gram benefit (max −1 to 23%) and binaural benefit (max −7.6 to 13%) for both groups. Individual data also showed a decrease in binaural interference in both groups after AI-Gram processing. These results suggest that the frequency and time ranges, intensified by the AI-Gram processing, contribute to consonant enhancement for monaural and binaural listening and both BCI and BHA technologies. The intensified frequency and time ranges helped to reduce binaural interference but contributed less to the synergistic binaural benefit in consonant recognition for both groups.

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Edvardsson Rasmussen, Jesper, Patrik Lundström, Per Olof Eriksson, Helge Rask-Andersen, Wei Liu, and Göran Laurell. "The Acute Effects of Furosemide on Na-K-Cl Cotransporter-1, Fetuin-A and Pigment Epithelium-Derived Factor in the Guinea Pig Cochlea." Frontiers in Molecular Neuroscience 15 (March 22, 2022). http://dx.doi.org/10.3389/fnmol.2022.842132.

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BackgroundFurosemide is a loop diuretic used to treat edema; however, it also targets the Na-K-Cl cotransporter-1 (NKCC1) in the inner ear. In very high doses, furosemide abolishes the endocochlear potential (EP). The aim of the study was to gain a deeper understanding of the temporal course of the acute effects of furosemide in the inner ear, including the protein localization of Fetuin-A and PEDF in guinea pig cochleae.Material and MethodAdult guinea pigs were given an intravenous injection of furosemide in a dose of 100 mg per kg of body weight. The cochleae were studied using immunohistochemistry in controls and at four intervals: 3 min, 30 min, 60 min and 120 min. Also, cochleae of untreated guinea pigs were tested for Fetuin-A and PEDF mRNA using RNAscope® technology.ResultsAt 3 min, NKCC1 staining was abolished in the type II fibrocytes in the spiral ligament, followed by a recovery period of up to 120 min. In the stria vascularis, the lowest staining intensity of NKCC1 presented after 30 min. The spiral ganglion showed a stable staining intensity for the full 120 min. Fetuin-A protein and mRNA were detected in the spiral ganglion type I neurons, inner and outer hair cells, pillar cells, Deiters cells and the stria vascularis. Furosemide induced an increased staining intensity of Fetuin-A at 120 min. PEDF protein and mRNA were found in the spiral ganglia type I neurons, the stria vascularis, and in type I and type II fibrocytes of the spiral ligament. PEDF protein staining intensity was high in the pillar cells in the organ of Corti. Furosemide induced an increased staining intensity of PEDF in type I neurons and pillar cells after 120 min.ConclusionThe results indicate rapid furosemide-induced changes of NKCC1 in the type II fibrocytes. This could be part of the mechanism that causes reduction of the EP within minutes after high dose furosemide injection. Fetuin-A and PEDF are present in many cells of the cochlea and probably increase after furosemide exposure, possibly as an otoprotective response.

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Journal articles on the topic 'Cochlear Gain Reduction'

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