Cochlear length determination using Cone Beam Computed Tomography in a clinical setting.
This study introduces a methodology to determine individual cochlear length in clinical setting by using Cone Beam Computed Tomography. METHODS: Cochlear length determination was performed retrospectively with an OsiriX curved 3D Multiplanar Reconstruction tool on subjects who underwent temporal bone imaging from January 2011 to February 2013. Cochlear length was defined as the spiral route from the center-distal point of the bony round window along the lateral wall towards the helicotrema, which is the endpoint of the measurement. RESULTS: Cochlear length was measured in 436 temporal bones (218 left ears, 218 ri...
Source: Hearing Research - August 11, 2014 Category: Audiology Authors: Würfel W, Lanfermann H, Lenarz T, Majdani O Tags: Hear Res Source Type: research

Abnormal intelligibility of speech in competing speech and in noise in a frequency region where audiometric thresholds are near-normal for hearing-impaired listeners.
nzi C Abstract The ability to identify syllables in the presence of speech-shaped noise and a single-talker background was measured for 18 normal-hearing (NH) listeners, and for eight hearing-impaired (HI) listeners with near-normal audiometric thresholds for frequencies up to 1.5 kHz and a moderate to severe hearing loss above 2 kHz. The stimulus components were restricted to the low-frequency (≤1.5 kHz) region, where audiometric thresholds were classified clinically as normal or near normal for all listeners. Syllable identification in a speech background was measured as a function of the fundamental-frequenc...
Source: Hearing Research - August 11, 2014 Category: Audiology Authors: Léger AC, Ives DT, Lorenzi C Tags: Hear Res Source Type: research

Differential modulation of auditory responses to attended and unattended speech in different listening conditions.
This study investigates how top-down attention modulates neural tracking of the speech envelope in different listening conditions. In the quiet conditions, a single speech stream was presented and the subjects paid attention to the speech stream (active listening) or watched a silent movie instead (passive listening). In the competing speaker (CS) conditions, two speakers of opposite genders were presented diotically. Ongoing electroencephalographic (EEG) responses were measured in each condition and cross-correlated with the speech envelope of each speaker at different time lags. In quiet, active and passive listening res...
Source: Hearing Research - August 11, 2014 Category: Audiology Authors: Kong YY, Mullangi A, Ding N Tags: Hear Res Source Type: research

Inner ear stem cells derived feeder layer promote directional differentiation of amniotic fluid stem cells into functional neurons.
Abstract Intact spiral ganglion neurons are required for cochlear implantation or conventional hearing amplification as an intervention for sensorineural hearing loss. Treatment strategies to replace the loss of spiral ganglion neurons are needed. Recent reports have suggested that amniotic fluid-derived stem cells are capable of differentiating into neuron-like cells in response to cytokines and are not tumorigenic. Amniotic fluid stem cells represent a potential resource for cellular therapy of neural deafness due to spiral ganglion pathology. However, the directional differentiation of amniotic fluid stem cells...
Source: Hearing Research - August 11, 2014 Category: Audiology Authors: Zong L, Chen K, Zhou W, Jiang D, Sun L, Zhang X, Jiang H Tags: Hear Res Source Type: research

The relation between auditory-nerve temporal responses and perceptual rate integration in cochlear implants.
Abstract The purpose of this study was to examine auditory-nerve temporal response properties and their relation to psychophysical threshold for electrical pulse trains of varying rates ("rate integration"). The primary hypothesis was that better rate integration (steeper slope) would be correlated with smaller decrements in ECAP amplitude as a function of stimulation rate (shallower slope of the amplitude-rate function), reflecting a larger percentage of the neural population contributing more synchronously to each pulse in the train. Data were obtained for 26 ears in 23 cochlear-implant recipients. Ele...
Source: Hearing Research - August 2, 2014 Category: Audiology Authors: Hughes ML, Baudhuin JL, Goehring JL Tags: Hear Res Source Type: research

Brain structural and functional alterations in patients with unilateral hearing loss.
In this study, we aim to investigate regional brain structural and functional alterations in patients with UHL. T1-weighted volumetric images and task-free fMRIs were acquired from 14 patients with right-sided UHL (pure tone average ≥ 40 dB HL) and 19 healthy controls. Hearing ability was assessed by pure tone audiometry. Voxel-based morphometry (VBM) was performed to detect brain regions with changed gray matter volume or white matter volume in UHL. The amplitude of low-frequency fluctuation (ALFF) was calculated to analyze brain activity at the baseline and was compared between two groups. Compared with controls, UHL...
Source: Hearing Research - August 2, 2014 Category: Audiology Authors: Yang M, Chen HJ, Liu B, Huang ZC, Feng Y, Li J, Chen JY, Zhang LL, Ji H, Feng X, Zhu X, Teng GJ Tags: Hear Res Source Type: research

Age-related hearing loss increases cross-modal distractibility.
Abstract Recent electrophysiological studies have provided evidence that changes in multisensory processing in auditory cortex cannot only be observed following extensive hearing loss, but also in moderately hearing-impaired subjects. How the reduced auditory input affects audio-visual interactions is however largely unknown. Here we used a cross-modal distraction paradigm to investigate multisensory processing in elderly participants with an age-related high-frequency hearing loss as compared to young and elderly subjects with normal hearing. During the experiment, participants were simultaneously presented with ...
Source: Hearing Research - July 28, 2014 Category: Audiology Authors: Puschmann S, Sandmann P, Bendixen A, Thiel CM Tags: Hear Res Source Type: research

Optimized loudness function estimation for categorical loudness scaling data.
Abstract Individual loudness perception can be assessed using categorical loudness scaling (CLS). The procedure does not require any training and is frequently used in clinics. The goal of this study was to investigate different methods of loudness function estimation from CLS data in terms of their test-retest behaviour and to suggest an improved method compared to Brand and Hohmann [J Acoust Soc Am 112:1597 (2002)] for adaptive CLS. Four different runs of the CLS procedure were conducted using 13 normal-hearing and 11 hearing-impaired listeners. The following approaches for loudness function estimation (fitting)...
Source: Hearing Research - July 21, 2014 Category: Audiology Authors: Oetting D, Brand T, Ewert SD Tags: Hear Res Source Type: research

The acoustical cues to sound location in the Guinea pig (cavia porcellus).
Abstract There are three main acoustical cues to sound location, each attributable to space-and frequency-dependent filtering of the propagating sound waves by the outer ears, head, and torso: Interaural differences in time (ITD) and level (ILD) as well as monaural spectral shape cues. While the guinea pig has been a common model for studying the anatomy, physiology, and behavior of binaural and spatial hearing, extensive measurements of their available acoustical cues are lacking. Here, these cues were determined from directional transfer functions (DTFs), the directional components of the head-related transfer f...
Source: Hearing Research - July 19, 2014 Category: Audiology Authors: Greene NT, Anbuhl KL, Williams W, Tollin DJ Tags: Hear Res Source Type: research

Peak I of the human auditory brainstem response results from the somatic regions of type I spiral ganglion cells: evidence from computer modeling.
Abstract Early neural responses to acoustic signals can be electrically recorded as a series of waves, termed the auditory brainstem response (ABR). The latencies of the ABR waves are important for clinical and neurophysiological evaluations. Using a biophysical model of transmembrane currents along spiral ganglion cells, we show that in human (i) the non-myelinated somatic regions of type I cells, which innervate inner hair cells, predominantly contribute to peak I, (ii) the supra-strong postsynaptic stimulating current (400 pA) and transmembrane currents of the myelinated peripheral axons of type I cells are an ...
Source: Hearing Research - July 11, 2014 Category: Audiology Authors: Rattay F, Danner SM Tags: Hear Res Source Type: research

T'ain't the way you say it, it's what you say - Perceptual continuity of voice and top-down restoration of speech.
Abstract Phonemic restoration, or top-down repair of speech, is the ability of the brain to perceptually reconstruct missing speech sounds, using remaining speech features, linguistic knowledge and context. This usually occurs in conditions where the interrupted speech is perceived as continuous. The main goal of this study was to investigate whether voice continuity was necessary for phonemic restoration. Restoration benefit was measured by the improvement in intelligibility of meaningful sentences interrupted with periodic silent gaps, after the gaps were filled with noise bursts. A discontinuity was induced on ...
Source: Hearing Research - July 11, 2014 Category: Audiology Authors: Clarke J, Gaudrain E, Chatterjee M, Başkent D Tags: Hear Res Source Type: research

Inner ear tissue preservation by rapid freezing: Improving fixation by high-pressure freezing and hybrid methods.
Abstract In the preservation of tissues in as 'close to life' state as possible, rapid freeze fixation has many benefits over conventional chemical fixation. One technique by which rapid freeze-fixation can be achieved, high pressure freezing (HPF), has been shown to enable ice crystal artefact-free freezing and tissue preservation to greater depths (more than 40 μm) than other quick-freezing methods. Despite increasingly becoming routine in electron microscopy, the use of HPF for the fixation of inner ear tissue has been limited. Assessment of the quality of preservation showed routine HPF techniques were...
Source: Hearing Research - July 10, 2014 Category: Audiology Authors: Bullen A, Taylor RR, Kachar B, Moores C, Fleck RA, Forge A Tags: Hear Res Source Type: research

Morphological brain network assessed using graph theory and network filtration in deaf adults.
Abstract Prolonged deprivation of auditory input can change brain networks in pre- and postlingual deaf adults by brain-wide reorganization. To investigate morphological changes in these brains voxel-based morphometry, voxel-wise correlation with the primary auditory cortex, and whole brain network analyses using morphological covariance were performed in eight prelingual deaf, eleven postlingual deaf, and eleven hearing adults. Network characteristics based on graph theory and network filtration based on persistent homology were examined. Gray matter density in the primary auditor cortex was preserved in prelingu...
Source: Hearing Research - July 10, 2014 Category: Audiology Authors: Kim E, Kang H, Lee H, Lee HJ, Suh MW, Song JJ, Oh SH, Lee DS Tags: Hear Res Source Type: research

Behavioral frequency discrimination ability of partially deafened cats using cochlear implants.
In this study we were able to show, for the first time, that cats can utilize information provided by a CI in performing a behavioral frequency discrimination task. PMID: 25008966 [PubMed - as supplied by publisher] (Source: Hearing Research)
Source: Hearing Research - July 4, 2014 Category: Audiology Authors: Benovitski YB, Blamey PJ, Rathbone GD, Fallon JB Tags: Hear Res Source Type: research

Acoustic trauma triggers upregulation of serotonin receptor genes.
Abstract Hearing loss induces plasticity in excitatory and inhibitory neurotransmitter systems in auditory brain regions. Excitatory-inhibitory balance is also influenced by a range of neuromodulatory regulatory systems, but less is known about the effects of auditory damage on these networks. In this work, we studied the effects of acoustic trauma on neuromodulatory plasticity in the auditory midbrain of CBA/J mice. Quantitative PCR was used to measure the expression of serotonergic and GABAergic receptor genes in the inferior colliculus (IC) of mice that were unmanipulated, sham controls with no hearing loss, an...
Source: Hearing Research - July 2, 2014 Category: Audiology Authors: Smith AR, Kwon JH, Navarro M, Hurley LM Tags: Hear Res Source Type: research

Place pitch versus electrode location in a realistic computational model of the implanted human cochlea.
Abstract Place pitch was investigated in a computational model of the implanted human cochlea containing nerve fibres with realistic trajectories that take the variable distance between the organ of Corti and spiral ganglion into account. The model was further updated from previous studies by including fluid compartments in the modiolus and updating the electrical conductivity values of (temporal) bone and the modiolus, based on clinical data. Four different cochlear geometries are used, modelled with both lateral and perimodiolar implants, and their neural excitation patterns were examined for nerve fibres modell...
Source: Hearing Research - June 26, 2014 Category: Audiology Authors: Kalkman RK, Briaire JJ, Dekker DM, Frijns JH Tags: Hear Res Source Type: research

Time course of cochlear injury discharge (excitotoxicity) determined by ABR monitoring of contralateral cochlear events.
Abstract The dynamics of cochlear excitotoxicity can be monitored from effects on the contralateral ear. After unilateral mechanical ablation of the cochlea (in a mouse model) we observed immediate elevations in auditory brainstem evoked response (ABR) thresholds in the contralateral ear. Threshold elevations peaked at 2-3 hrs post ablation, and returned to baseline levels after 5-6 hrs. These contralateral effects are initiated by cochlear afferent injury discharges most likely activating the olivocochlear efferent system. Six hours after cochlear injury, ABR thresholds were fully returned to pre-lesion baseline ...
Source: Hearing Research - June 25, 2014 Category: Audiology Authors: Negandhi J, Harrison AL, Allemang C, Harrison RV Tags: Hear Res Source Type: research

Effects of deafness and cochlear implant use on temporal response characteristics in cat primary auditory cortex.
Abstract We have previously shown that neonatal deafness of 7-13 months duration leads to loss of cochleotopy in the primary auditory cortex (AI) that can be reversed by cochlear implant use. Here we describe the effects of a similar duration of deafness and cochlear implant use on temporal processing. Specifically, we compared the temporal resolution of neurons in AI of young adult normal-hearing cats that were acutely deafened and implanted immediately prior to recording with that in three groups of neonatally deafened cats. One group of neonatally deafened cats received no chronic stimulation. The other two gro...
Source: Hearing Research - June 14, 2014 Category: Audiology Authors: Fallon JB, Shepherd RK, Nayagam DA, Wise AK, Heffer LF, Landry TG, Irvine DR Tags: Hear Res Source Type: research

miR-204 suppresses cochlear spiral ganglion neuron survival in vitro by targeting TMPRSS3.
miR-204 suppresses cochlear spiral ganglion neuron survival in vitro by targeting TMPRSS3. Hear Res. 2014 Jun 9; Authors: Li Y, Peng A, Ge S, Wang Q, Liu J Abstract Sensorineural hearing loss (SNHL) is the most common cause of hearing impairment. One of the essential steps to prevent progressive hearing loss is to protect spiral ganglion neurons (SGNs) from ongoing degeneration. MicroRNAs and TMPRSS3 (transmembrane protease, serine 3) have been reported to be involved in development of SGNs and genesis of SNHL. The aim of this study was to investigate the role of miR-204 and TMPRSS3 in SGNs. Effe...
Source: Hearing Research - June 9, 2014 Category: Audiology Authors: Li Y, Peng A, Ge S, Wang Q, Liu J Tags: Hear Res Source Type: research

The auditory corticocollicular system: Molecular and circuit-level considerations.
Abstract We live in a world imbued with a rich mixture of complex sounds. Successful acoustic communication requires the ability to extract meaning from those sounds, even when degraded. One strategy used by the auditory system is to harness high-level contextual cues to modulate the perception of incoming sounds. An ideal substrate for this process is the massive set of top-down projections emanating from virtually every level of the auditory system. In this review, we provide a molecular and circuit-level description of one of the largest of these pathways: the auditory corticocollicular pathway. While its funct...
Source: Hearing Research - June 7, 2014 Category: Audiology Authors: Stebbings KA, Lesicko AM, Llano DA Tags: Hear Res Source Type: research

Prolonged sound exposure has different effects on increasing neuronal size in the auditory cortex and brainstem.
Abstract Tone at moderate levels presented to young rats at a stage (postnatal week-4) presumably that has passed the cortical critical period still can enlarge neurons in the auditory cortex. It remains unclear whether this delayed plastic change occurs only in the cortex, or reflects a change taking place in the auditory brainstem. Here we compared sound-exposure effects on neuronal size in the auditory cortex and the midbrain. Starting from postnatal day 22, young rats were exposed to a low-frequency tone (4 kHz at 65 dB SPL) for a period of 3 (postnatal day 22 to 25) or 7 (postnatal day 22 to 29) day...
Source: Hearing Research - June 6, 2014 Category: Audiology Authors: Lu HP, Syka J, Chiu TW, Poon PW Tags: Hear Res Source Type: research

Primary culture of human Schwann and schwannoma cells: Improved and simplified protocol.
Abstract Primary culture of human Schwann cells (SCs) and vestibular schwannoma (VS) cells are invaluable tools to investigate SC physiology and VS pathobiology, and to devise effective pharmacotherapies against VS, which are sorely needed. However, existing culture protocols, in aiming to create robust, pure cultures, employ methods that can lead to loss of biological characteristics of the original cells, potentially resulting in misleading biological findings. We have developed a minimally manipulative method to culture primary human SC and VS cells, without the use of selective mitogens, toxins, or time-consum...
Source: Hearing Research - June 5, 2014 Category: Audiology Authors: Dilwali S, Patel PB, Roberts DS, Basinsky GM, Harris GJ, Emerick K, Stankovic KM Tags: Hear Res Source Type: research

A novel perfusion-based method for cochlear implant electrode insertion.
Abstract A cochlear implant (CI) restores partial hearing to profoundly deaf individuals. CI electrodes are inserted manually in the cochlea and surgeons rely on tactile feedback from the implant to determine when to stop the insertion. This manual insertion method results in a large degree of variability in surgical outcomes and intra-cochlear trauma. Additionally, implants often span only the basal turn. In the present study we report on the development of a new method to assist CI electrode insertion. The design objectives are (1) an automated and standardized insertion technique across patients with (2) more a...
Source: Hearing Research - May 29, 2014 Category: Audiology Authors: Kale S, Cervantes VM, Wu MR, Pisano DV, Sheth N, Olson ES Tags: Hear Res Source Type: research

Localization of kainate receptors in inner and outer hair cell synapses.
har B Abstract Glutamate plays a role in hair cell afferent transmission, but the receptors that mediate neurotransmission between outer hair cells (OHCs) and type II ganglion neurons are not well defined. A previous study using in situ hybridization showed that several kainate-type glutamate receptor (KAR) subunits are expressed in cochlear ganglion neurons. To determine whether KARs are expressed in hair cell synapses, we performed X-gal staining on mice expressing lacZ driven by the GluK5 promoter, and immunolabeling of glutamate receptors in whole-mount mammalian cochleae. X-gal staining revealed GluK5 express...
Source: Hearing Research - May 20, 2014 Category: Audiology Authors: Fujikawa T, Petralia RS, Fitzgerald TS, Wang YX, Millis B, Morgado-Díaz JA, Kitamura K, Kachar B Tags: Hear Res Source Type: research

Psychometric function of jittered rate pitch discrimination.
In conclusion, pulse rate jitter affects JRPD and therefore should be considered in current coding strategies. PMID: 24821551 [PubMed - as supplied by publisher] (Source: Hearing Research)
Source: Hearing Research - May 10, 2014 Category: Audiology Authors: Bahmer A, Baumann U Tags: Hear Res Source Type: research

Brainstem response to speech and non-speech stimuli in children with learning problems.
Abstract Neuronal firing synchronization is critical for recording auditory responses from the brainstem. Recent studies have shown that both click and/da/synthetic syllable (speech) stimuli perform well in evoking neuronal synchronization at the brainstem level. In the present study, brainstem responses to click and speech stimuli were compared between children with learning problems (LP) and those with normal learning (NL) abilities. The study included 49 children with LP and 34 children with NL. Auditory brainstem response (ABR) to 100-μs click stimulus and speech ABR (sABR) to/da/40-ms stimulus were tested ...
Source: Hearing Research - May 10, 2014 Category: Audiology Authors: Malayeri S, Lotfi Y, Moossavi SA, Rostami R, Faghihzadeh S Tags: Hear Res Source Type: research

Individual differences in attentional modulation of cortical responses correlate with selective attention performance.
Abstract Many studies have shown that attention modulates the cortical representation of an auditory scene, emphasizing an attended source while suppressing competing sources. Yet, individual differences in the strength of this attentional modulation and their relationship with selective attention ability are poorly understood. Here, we ask whether differences in how strongly attention modulates cortical responses reflect differences in normal-hearing listeners' selective auditory attention ability. We asked listeners to attend to one of three competing melodies and identify its pitch contour while we measured cor...
Source: Hearing Research - May 9, 2014 Category: Audiology Authors: Choi I, Wang L, Bharadwaj H, Shinn-Cunningham B Tags: Hear Res Source Type: research

The connexin 30.3 of zebrafish homologue of human connexin 26 may play similar role in the inner ear.
In this study, using bioinformatics, we found that two zebrafish cx genes, cx27.5 and cx30.3, are likely homologous to human and mouse GJB2. During embryogenesis, zebrafish cx27.5 was rarely expressed at 1.5-3 hours post-fertilization (hpf), but a relatively high level of cx27.5 expression was detected from 6-96 hpf. However, zebrafish cx30.3 transcripts were hardly detected until 9 hpf. The temporal experiment was conducted in whole larvae. Both cx27.5 and cx30.3 transcripts were revealed significantly in the inner ear by reverse transcription polymerase chain reaction (RT-PCR) and whole-mount in situ hybridization (WISH)...
Source: Hearing Research - May 5, 2014 Category: Audiology Authors: Chang-Chien J, Yen YC, Chien KH, Li SY, Hsu TC, Yang JJ Tags: Hear Res Source Type: research

Behavioral responses of deafened guinea pigs to intracochlear electrical stimulation: A new rapid psychophysical procedure.
In conclusion, the present study demonstrates that guinea pigs can be trained relatively fast to respond to acoustic stimuli, and that the training has a lasting effect, which generalizes to intracochlear electrical stimulation after deafening. Furthermore, it demonstrates that bilaterally deafened guinea pigs with substantial (∼50%) loss of spiral ganglion cells (SGCs), detect intracochlear electrical stimulation. PMID: 24811981 [PubMed - as supplied by publisher] (Source: Hearing Research)
Source: Hearing Research - May 5, 2014 Category: Audiology Authors: Agterberg MJ, Versnel H Tags: Hear Res Source Type: research

Acetaminophen and NAPQI are toxic to auditory cells via oxidative and endoplasmic reticulum stress-dependent pathways.
In this study, we report cellular, genomic, and proteomic experiments revealing that cytotoxicity by APAP and NAPQI involves two different pathways in Immortomouse™-derived HEI-OC1 cells, implicating ROS overproduction, alterations in ER morphology, redistribution of intra-cisternal chaperones, activation of the eIF2α-CHOP pathway, as well as changes in ER stress and protein folding response markers. Thus, both oxidative and ER stress are part of the cellular and molecular mechanisms that contribute to the cytotoxic effects of APAP and NAPQI in these cells. We suggest that these in vitro findings should be...
Source: Hearing Research - April 30, 2014 Category: Audiology Authors: Kalinec GM, Thein P, Parsa A, Yorgason J, Luxford W, Urrutia R, Kalinec F Tags: Hear Res Source Type: research

Effects of the intensity of masking noise on ear canal recorded low-frequency cochlear microphonic waveforms in normal hearing subjects.
In conclusion, when masked with high-pass noise, the low-frequency CMs are measurable at the human ear canal. Such noise reduces the low-frequency CM amplitude. The reduction is noise-intensity dependent but not completely linear. The reduction may be caused by the excited basal cochlea which the low-frequency has to travel and pass through. Although not completely clear, six mechanisms related to such reduction are discussed. PMID: 24793117 [PubMed - as supplied by publisher] (Source: Hearing Research)
Source: Hearing Research - April 30, 2014 Category: Audiology Authors: Zhang M Tags: Hear Res Source Type: research

Thin and open vessel windows for intra-vital fluorescence imaging of murine cochlear blood flow.
Abstract Normal microvessel structure and function in the cochlea is essential for maintaining the ionic and metabolic homeostasis required for hearing function. Abnormal cochlear microcirculation has long been considered an etiologic factor in hearing disorders. A better understanding of cochlear blood flow (CoBF) will enable more effective amelioration of hearing disorders that result from aberrant blood flow. However, establishing the direct relationship between CoBF and other cellular events in the lateral wall and response to physio-pathological stress remains a challenge due to the lack of feasible interroga...
Source: Hearing Research - April 26, 2014 Category: Audiology Authors: Shi X, Zhang F, Urdang Z, Dai M, Neng L, Zhang J, Chen S, Ramamoorthy S, Nuttall AL Tags: Hear Res Source Type: research

Comparison of auditory responses determined by acoustic stimulation and by mechanical round window stimulation at equivalent stapes velocities.
In conclusion, this study showed that the amplitudes and latencies of the ABRs of acoustic and RW stimulation showed significant differences at comparable stapes velocities in an in vivo system. These differences in the ABR amplitudes and latencies reflect different output functions of the cochlea in response to different stimulation pathways. Therefore, it is necessary to develop a new method for quantifying the output of the cochlea in the case of RW stimulation. PMID: 24768763 [PubMed - as supplied by publisher] (Source: Hearing Research)
Source: Hearing Research - April 24, 2014 Category: Audiology Authors: Lee J, Seong K, Lee SH, Lee KY, Cho JH Tags: Hear Res Source Type: research

Time-frequency analysis of transient evoked-otoacoustic emissions in individuals with auditory neuropathy spectrum disorder.
Abstract The aim of the study was to describe and quantify the cochlear active mechanisms in individuals with Auditory Neuropathy Spectrum Disorders (ANSD). Transient Evoked Otoacoustic Emissions (TEOAEs) were recorded in 15 individuals with ANSD and 22 individuals with normal hearing. TEOAEs were analyzed by Wavelet transform method to describe and quantify the characteristics of TEOAEs in narrow-band frequency regions. It was noted that the amplitude of TEOAEs was higher and latency slightly shorter in individuals with ANSD compared to normal hearing individuals at low and mid frequencies. The increased amplitud...
Source: Hearing Research - April 24, 2014 Category: Audiology Authors: Narne VK, Prabhu PP, Chatni S Tags: Hear Res Source Type: research

Loudness perception affected by early age hearing loss.
In this study, sound loudness changes in rats affected by perforation of the tympanic membranes (TM) have been studied using an operant conditioning based behavioral task. We detected significant increases of sound loudness and susceptibility to audiogenic seizures (AGS) in rats with bilateral TM damage at postnatal 16 days. As increase to sound sensitivity is commonly seen in hyperacusis and tinnitus patients, these results suggest that early age hearing loss is a high risk factor to induce tinnitus and hyperacusis in children. In the TM damaged rats, we also detected a reduced expression of GABA receptor δ and &alp...
Source: Hearing Research - April 18, 2014 Category: Audiology Authors: Sun W, Fu Q, Zhang C, Manohar S, Kumaraguru A, Li J Tags: Hear Res Source Type: research

Modeling the utility of binaural cues for underwater sound localization.
Abstract The binaural cues used by terrestrial animals for sound localization in azimuth may not always suffice for accurate sound localization underwater. The purpose of this research was to examine the theoretical limits of interaural timing and level differences available underwater using computational and physical models. A paired-hydrophone system was used to record sounds transmitted underwater and recordings were analyzed using neural networks calibrated to reflect the auditory capabilities of terrestrial mammals. Estimates of source direction based on temporal differences were most accurate for frequencies...
Source: Hearing Research - April 12, 2014 Category: Audiology Authors: Schneider JN, Lloyd DR, Banks PN, Mercado E Tags: Hear Res Source Type: research

Selective attention reduces physiological noise in the external ear canals of humans. I: Auditory attention.
In this study, a nonlinear version of the stimulus-frequency OAE (SFOAE), called the nSFOAE, was used to measure cochlear responses from human subjects while they simultaneously performed behavioral tasks requiring, or not requiring, selective auditory attention. Appended to each stimulus presentation, and included in the calculation of each nSFOAE response, was a 30-ms silent period that was used to estimate the level of the inherent physiological noise in the ear canals of our subjects during each behavioral condition. Physiological-noise magnitudes were higher (noisier) for all subjects in the inattention task, and lowe...
Source: Hearing Research - April 11, 2014 Category: Audiology Authors: Walsh KP, Pasanen EG, McFadden D Tags: Hear Res Source Type: research

Selective attention reduces physiological noise in the external ear canals of humans. II: Visual attention.
Abstract Human subjects performed in several behavioral conditions requiring, or not requiring, selective attention to visual stimuli. Specifically, the attentional task was to recognize strings of digits that had been presented visually. A nonlinear version of the stimulus-frequency otoacoustic emission (SFOAE), called the nSFOAE, was collected during the visual presentation of the digits. The segment of the physiological response discussed here occurred during brief silent periods immediately following the SFOAE-evoking stimuli. For all subjects tested, the physiological-noise magnitudes were substantially weake...
Source: Hearing Research - April 11, 2014 Category: Audiology Authors: Walsh KP, Pasanen EG, McFadden D Tags: Hear Res Source Type: research

Round Window Stimulation with the Floating Mass Transducer at Constant Pretension.
Abstract OBJECTIVE: Mechanical stimulation of the round window (RW) of the cochlea is successfully done with the Vibrant Soundbridge (Med-El), but clinical outcomes show a substantial degree of variability. One source of variability is variation in the pre-load static force applied by the stimulator to the round window (Maier et al., 2013), in this study we investigate other sources of variability by maintaining a constant static-force pre-load while investigating the effect of a coupler device and the interposition of soft tissue between the stimulator and the RW. STUDY DESIGN: Experimental METHODS: The stap...
Source: Hearing Research - April 10, 2014 Category: Audiology Authors: Salcher R, Schwab B, Lenarz T, Maier H Tags: Hear Res Source Type: research

Natural variability in species-specific vocalizations constrains behavior and neural activity.
Abstract A listener's capacity to discriminate between sounds is related to the amount of acoustic variability that exists between these sounds. However, a full understanding of how this natural variability impacts neural activity and behavior is lacking. Here, we tested monkeys' ability to discriminate between different utterances of vocalizations from the same acoustic class (i.e., coos and grunts), while neural activity was simultaneously recorded in the anterolateral belt region (AL) of the auditory cortex, a brain region that is a part of a pathway that mediates auditory perception. Monkeys could discriminate...
Source: Hearing Research - April 7, 2014 Category: Audiology Authors: Christison-Lagay KL, Bennur S, Blackwell J, Lee JH, Schroeder T, Cohen YE Tags: Hear Res Source Type: research

Photons and Neurons.
Abstract Methods to control neural activity by light have been introduced to the field of neuroscience. During the last decade, several techniques have been established, including optogenetics, thermogenetics, and infrared neural stimulation. The techniques allow investigators to turn-on or turn-off neural activity. This review is an attempt to show the importance of the techniques for the auditory field and provide insight in the similarities, overlap, and differences of the techniques. Discussing the mechanism of each of the techniques will shed light on the abilities and challenges for each of the techniques. T...
Source: Hearing Research - April 4, 2014 Category: Audiology Authors: Richter CP, Tan X Tags: Hear Res Source Type: research

Independent or integrated processing of interaural time and level differences in human auditory cortex?
We presented a series of diotic standards (perceived at a midline position) that were interrupted by deviants that entailed either a change in a) ITD only, b) ILD only, c) congruent ITD and ILD, or d) counterbalanced ITD/ILD (ITD/ILD trading). The sound stimuli were either i) pure tones with a frequency of 500 Hz, or ii) amplitude modulated tones with a carrier frequency of 4000 Hz and a modulation frequency of 125 Hz. We observed significant MMN for the ITD/ILD traded deviants in case of the 500 Hz pure tones, and for the 4000 Hz amplitude-modulated tone. This speaks for independent processing of ITD and ILD at the level ...
Source: Hearing Research - April 4, 2014 Category: Audiology Authors: Altmann CF, Terada S, Kashino M, Goto K, Mima T, Fukuyama H, Furukawa S Tags: Hear Res Source Type: research

The pupil response is sensitive to divided attention during speech processing.
Abstract Dividing attention over two streams of speech strongly decreases performance compared to focusing on only one. How divided attention affects cognitive processing load as indexed with pupillometry during speech recognition has so far not been investigated. In 12 young adults the pupil response was recorded while they focused on either one or both of two sentences that were presented dichotically and masked by fluctuating noise across a range of signal-to-noise ratios. In line with previous studies, the performance decreases when processing two target sentences instead of one. Additionally, dividing attenti...
Source: Hearing Research - April 4, 2014 Category: Audiology Authors: Koelewijn T, Shinn-Cunningham BG, Zekveld AA, Kramer SE Tags: Hear Res Source Type: research

Source analysis of short and long latency vestibular-evoked potentials (VsEPs) produced by left vs. right ear air-conducted 500 Hz pips.
Source analysis of short and long latency vestibular-evoked potentials (VsEPs) produced by left vs. right ear air-conducted 500 Hz pips. Hear Res. 2014 Apr 1; Authors: Todd NP, Paillard AC, Kluk K, Whittle E, Colebatch JG Abstract Todd et al. (2014) have recently demonstrated the presence of vestibular dependent changes both in the morphology and in the intensity dependence of auditory evoked potentials (AEPs) when passing through the vestibular threshold as determined by vestibular evoked myogenic potentials (VEMPs). In this paper we extend this work by comparing left vs. right ear stimulat...
Source: Hearing Research - April 1, 2014 Category: Audiology Authors: Todd NP, Paillard AC, Kluk K, Whittle E, Colebatch JG Tags: Hear Res Source Type: research

Viscoelastic properties of the human tympanic membrane studied with stroboscopic holography and finite element modeling.
Abstract A new anatomically-accurate Finite Element (FE) model of the tympanic membrane (TM) and malleus was combined with measurements of the sound-induced motion of the TM surface and the bony manubrium, in an isolated TM-malleus preparation. Using the results, we were able to address two issues related to how sound is coupled to the ossicular chain: (i) Estimate the viscous damping within the tympanic membrane itself, the presence of which may help smooth the broadband response of a potentially highly resonant TM, and (ii) Investigate the function of a peculiar feature of human middle-ear anatomy, the thin muco...
Source: Hearing Research - March 19, 2014 Category: Audiology Authors: De Greef D, Aernouts J, Aerts J, Cheng JT, Horwitz R, Rosowski JJ, Dirckx JJ Tags: Hear Res Source Type: research

The dissimilar time course of temporary threshold shifts and reduction of inhibition in the inferior colliculus following intense sound exposure.
Abstract Excessive noise exposure is known to produce an auditory threshold shift, which can be permanent or transient in nature. Recent studies showed that noise-induced temporary threshold shifts are associated with loss of synaptic connections to the inner hair cells and with cochlear nerve degeneration, which is reflected in a decreased amplitude of wave I of the auditory brainstem response (ABR). This suggests that, despite normal auditory thresholds, central auditory processing may be abnormal. We recorded changes in central auditory processing following a sound-induced temporary threshold shift. Anesthetize...
Source: Hearing Research - March 18, 2014 Category: Audiology Authors: Heeringa AN, van Dijk P Tags: Hear Res Source Type: research

Mechanisms of radiation-induced sensorineural hearing loss and radioprotection.
Abstract Patients that receive radiotherapy are at risk of late sensorineural hearing loss when the inner ear is included within the radiation field. Preclinical and human temporal bone studies have shown that there is differential damage to cochlear structures depending on the amount of dose delivered to the inner ear. In vitro studies have suggested that reactive oxygen species (ROS) are the main initial actors in radiation-induced damage. The interaction of ROS with different cellular components can result in different apoptotic pathways. Therefore, approaches to radioprotection are mainly aimed to reduce ...
Source: Hearing Research - March 18, 2014 Category: Audiology Authors: Mujica-Mota MA, Lehnert S, Devic S, Gasbarrino K, Daniel SJ Tags: Hear Res Source Type: research

Cochlear implantation in the mouse via the round window: Effects of array insertion.
Cochlear implantation in the mouse via the round window: Effects of array insertion. Hear Res. 2014 Mar 18; Authors: Mistry N, Nolan LS, Saeed SR, Forge A, Taylor RR Abstract Animal models are the only means of assessing the effects of cochlear implantation (CI) at a cellular and molecular level. The range of naturally occurring and genetically-modified mouse strains which mimic human deafness provide excellent opportunities for auditory research. To date, there are very few studies of CI in mice. The main aims of this study were to develop a reproducible and viable technique to enable long term CI in...
Source: Hearing Research - March 18, 2014 Category: Audiology Authors: Mistry N, Nolan LS, Saeed SR, Forge A, Taylor RR Tags: Hear Res Source Type: research

Tinnitus-related dissociation between cortical and subcortical neural activity in humans with mild to moderate sensorineural hearing loss.
In this study, cortical and sub-cortical sound-evoked brain responses in 34 hearing-impaired chronic tinnitus patients and 19 hearing level-matched controls were studied using 3-T functional magnetic resonance imaging (fMRI). Auditory stimuli were presented to either the left or the right ear at levels of 30-90 dB SPL. We extracted neural activation as a function of sound intensity in eight auditory regions (left and right auditory cortices, medial geniculate bodies, inferior colliculi and cochlear nuclei), the cerebellum and a cinguloparietal task-positive region. The activation correlated positively with the stimulus int...
Source: Hearing Research - March 11, 2014 Category: Audiology Authors: Boyen K, de Kleine E, van Dijk P, Langers DR Tags: Hear Res Source Type: research

Localization and interaural time difference (ITD) thresholds for cochlear implant recipients with preserved acoustic hearing in the implanted ear.
Abstract The purpose of this study was to investigate horizontal plane localization and interaural time difference (ITD) thresholds for 14 adult cochlear implant recipients with hearing preservation in the implanted ear. Localization to broadband noise was assessed in an anechoic chamber with a 33-loudspeaker array extending from -90 to +90 degrees. Three listening conditions were tested including bilateral hearing aids, bimodal (implant + contralateral hearing aid) and best aided (implant + bilateral hearing aids). ITD thresholds were assessed, under headphones, for low-frequency stimuli including a 250-Hz tone a...
Source: Hearing Research - March 6, 2014 Category: Audiology Authors: Gifford RH, Grantham DW, Sheffield SW, Davis TJ, Dwyer R, Dorman MF Tags: Hear Res Source Type: research