OBJECTIVE: To study the relationship of distortion product in cochlea with cochlear activity and hearing. METHOD: Time variances of distortion product of basilar membrane vibration in vitro guineapig cochlea were observed by laser interferometry. RESULT: Within half hour after a cochlea was isolated from a guineapig, distortion product accompanied with two-tone inhibition in cochlea, can be observed. As time passed, distortion product and two-tone inhibition effect disappeared at the same time. After that, the membrane contiune vibrating in response to the sound stimulus, but the vibration amplitude decreased obviously and continued decreasing until it disappeared completely. CONCLUSION Distortion product in cochlea is a symbol of cochlear activity which makes the membrane respond in large amplitude vibration to sound stimulus and exhibit two-tone inhibition. The former makes the hearing highly sensitive to sound stimulus, the later makes the hearing perform information abstract well.
Acoustic Stimulation ; Animals ; Basilar Membrane ; physiology ; Cochlea ; physiology ; Guinea Pigs ; Hearing ; physiology ; Hearing Tests ; Interferometry ; Sound

Objective:This study aims to analyze the threshold changes in distortion product otoacoustic emissions（DPOAE） and auditory brainstem response（ABR） in adult Otof-/- mice before and after gene therapy, evaluating its effectiveness and exploring methods for assessing hearing recovery post-treatment. Methods:At the age of 4 weeks, adult Otof-/- mice received an inner ear injection of a therapeutic agent containing intein-mediated recombination of the OTOF gene, delivered via dual AAV vectors through the round window membrane（RWM）. Immunofluorescence staining assessed the proportion of inner ear hair cells with restored otoferlin expression and the number of synapses.Statistical analysis was performed to compare the DPOAE and ABR thresholds before and after the treatment. Results:AAV-PHP. eB demonstrates high transduction efficiency in inner ear hair cells. The therapeutic regimen corrected hearing loss in adult Otof-/- mice without impacting auditory function in wild-type mice. The changes in DPOAE and ABR thresholds after gene therapy are significantly correlated at 16 kHz. Post-treatment,a slight increase in DPOAE was observeds,followed by a recovery trend at 2 months post-treatment. Conclusion:Gene therapy significantly restored hearing in adult Otof-/- mice, though the surgical delivery may cause transient hearing damage. Precise and gentle surgical techniques are essential to maximize gene therapy's efficacy.
Mice ; Animals ; Otoacoustic Emissions, Spontaneous/physiology* ; Hearing/physiology* ; Ear, Inner ; Hearing Loss/therapy* ; Genetic Therapy ; Auditory Threshold/physiology* ; Evoked Potentials, Auditory, Brain Stem/physiology* ; Membrane Proteins

BACKGROUNDMany factors interfering with a listener attempting to grasp speech in noisy environments. The spatial hearing by which speech and noise can be spatially separated may play a crucial role in speech recognition in the presence of competing noise. This study aimed to assess whether, and to what degree, spatial hearing benefit speech recognition in young normal-hearing participants in both quiet and noisy environments.

METHODSTwenty-eight young participants were tested by Mandarin Hearing In Noise Test (MHINT) in quiet and noisy environments. The assessment method used was characterized by modifications of speech and noise configurations, as well as by changes of speech presentation mode. The benefit of spatial hearing was measured by speech recognition threshold (SRT) variation between speech condition 1 (SC1) and speech condition 2 (SC2).

RESULTSThere was no significant difference found in the SRT between SC1 and SC2 in quiet. SRT in SC1 was about 4.2 dB lower than that in SC2, both in speech-shaped and four-babble noise conditions. SRTs measured in both SC1 and SC2 were lower in the speech-shaped noise condition than in the four-babble noise condition.

CONCLUSIONSpatial hearing in young normal-hearing participants contribute to speech recognition in noisy environments, but provide no benefit to speech recognition in quiet environments, which may be due to the offset of auditory extrinsic redundancy against the lack of spatial hearing.

Adolescent ; Adult ; Auditory Threshold ; physiology ; Female ; Hearing ; physiology ; Humans ; Male ; Noise ; Speech Perception ; physiology ; Speech Reception Threshold Test ; Young Adult

Auditory Perception ; physiology ; Child Development ; physiology ; Hearing ; physiology ; Humans ; Infant, Newborn ; growth & development ; Intensive Care Units, Neonatal ; Noise ; adverse effects

Child, Preschool ; Early Diagnosis ; Evoked Potentials, Auditory, Brain Stem ; Hearing ; physiology ; Hearing Loss ; diagnosis ; Humans ; Infant ; Otoacoustic Emissions, Spontaneous

Stimulation of the round window (RW) for coupling an implantable hearing system to the cochlea has gained increasing clinical importance. To compare the vibration transfer to the cochlear fluids and partition in response to normal acoustic stimulation and to mechanical stimulation of the RW, we carried out an acoustic-structure coupled finite element analysis using a recently developed finite element (FE) model in our laboratory, which consisted of external ear canal, middle ear and cochlea. Intracochlear pressures were derived during normal forward sound stimulation as well as reverse RW stimulation. A model was utilized to calculate the force required of an actuator at the RW to produce a differential intracochlear pressure that is equivalent to a stimulus produced in normal ear by a given external ear-canal pressure. The current results provided further information to support the optimization of the actuators and adapt existing prostheses for RW stimulation in order to insure sufficient acoustic output.
Acoustic Stimulation ; Cochlea ; physiology ; Cochlear Microphonic Potentials ; physiology ; Ear Canal ; physiology ; Finite Element Analysis ; Hearing Aids ; Humans ; Ossicular Prosthesis ; Pressure ; Round Window, Ear ; physiology ; Vibration

A new method in OAE's measurement by computer sound card is introduced. It is a measurement system using SF-1 detector. We designed the appropriate analog filter amplifier peripheral, utilized the mature technology of computer sound card, and recorded the OAE signal using Windows' API function programming by VB. The recorded signals can be analyzed by Matlab, such as digital filtering and Coherence average. The system is, in the main, cost-effective. The statistical results of the experiments proved the reliability of the method.
Acoustic Stimulation ; Cochlea ; physiology ; Evoked Potentials ; Hearing Tests ; instrumentation ; Humans ; Otoacoustic Emissions, Spontaneous ; physiology ; Signal Processing, Computer-Assisted ; instrumentation ; Sound

OBJECTIVETo evaluate the effect of low frequency and high frequency tympanometry in the diagnosis of middle ear function of infants.

METHODSTympanometries with 226 Hz, 678 Hz and 1000 Hz probe tones were obtained from infants aged 5-25 weeks with normal ABR (15 infants, 30 ears) and those with prolonged Wave I latency suggesting middle ear dysfunction (17 infants, 20 ears) using GSI Tympstar middle ear analyzer.

RESULTSThe type, peak pressure, peak compensated static acoustic admittance and gradient of 226 Hz tympanometry were of no significant differences between two groups. The pattern of 678 Hz tympanograms for admittance, susceptance and conductance included non-peaked, single-peaked, W-shaped and three-peaked type in both groups. The consistency between auditory brainstem response (ABR) and 678Hz tympanometry for admittance, susceptance and conductance were 70.0%, 58.0%, 64.0% (kappa = 0. 324,0. 234,0. 118) respectively. A single peaked tympanogram was typical in normal infants for 1000 Hz admittance, susceptance and conductance tympanograms and there were 28 ears (93.3%), 25 ears (83.3%) and 26 (86.7%) respectively. Tympanogram without any positive peak was the most characteristic for a probe frequency of 1000 Hz in infants with prolonged wave I latency and there were 15 ears (75%), 17 ears (85%) and 13 ears (65%) respectively. For admittance, susceptance and conductance, the consistency between 1000 Hz tympanometry and ABR were 90.0%, 92.0% and 86.0% and kappa were 0.783, 0.831 and 0.690, respectively.

CONCLUSIONS1000 Hz probe tone tympanometry was accurate diagnostic tests for middle ear function in infants younger than 25 weeks of age, while 226 Hz and 678 Hz probe tone tympanometries were not.

Acoustic Impedance Tests ; Ear, Middle ; physiology ; Evoked Potentials, Auditory, Brain Stem ; physiology ; Female ; Hearing Tests ; methods ; Humans ; Infant ; Male

More than 80% of all cases of deafness are related to the death or degeneration of cochlear hair cells and the associated spiral ganglion neurons, and a lack of regeneration of these cells leads to permanent hearing loss. Therefore, the regeneration of lost hair cells is an important goal for the treatment of deafness. Atoh1 is a basic helix-loop-helix (bHLH) transcription factor that is critical in both the development and regeneration of cochlear hair cells. Atoh1 is transcriptionally regulated by several signaling pathways, including Notch and Wnt signalings. At the post-translational level, it is regulated through the ubiquitin-proteasome pathway. In vitro and in vivo studies have revealed that manipulation of these signaling pathways not only controls development, but also leads to the regeneration of cochlear hair cells after damage. Recent progress toward understanding the signaling networks involved in hair cell development and regeneration has led to the development of new strategies to replace lost hair cells. This review focuses on our current understanding of the signaling pathways that regulate Atoh1 in the cochlea.
Basic Helix-Loop-Helix Transcription Factors/physiology* ; Cell Differentiation ; Cochlea/physiology* ; Hair Cells, Auditory/physiology* ; Hearing Loss/etiology* ; Humans ; Proteasome Endopeptidase Complex/physiology* ; Signal Transduction/physiology* ; Transcription Factors/physiology* ; Ubiquitin/metabolism* ; Wnt Signaling Pathway ; beta Catenin/physiology*

BACKGROUNDDetermining the nerve of origin for vestibular schwannoma (VS), as a method for predicting hearing prognosis, has not been systematically considered. The vestibular test can be used to investigate the function of the superior vestibular nerve (SVN) and the inferior vestibular nerve (IVN). This study aimed to preoperatively distinguish the nerve of origin for VS patients using the vestibular test, and determine if this correlated with hearing preservation.

METHODSA total of 106 patients with unilateral VS were enrolled in this study prospectively. Each patient received a caloric test, vestibular-evoked myogenic potential (VEMP) test, and cochlear nerve function test (hearing) before the operation and 1 week, 3, and 6 months, postoperatively. All patients underwent surgical removal of the VS using the suboccipital approach. During the operation, the nerve of tumor origin (SVN or IVN) was identified by the surgeon. Tumor size was measured by preoperative magnetic resonance imaging.

RESULTSThe nerve of tumor origin could not be unequivocally identified in 38 patients (38/106, 35.80%). These patients were not subsequently evaluated. In 26 patients (nine females, seventeen males), tumors arose from the SVN and in 42 patients (18 females, 24 males), tumors arose from the IVN. Comparing with the nerve of origins (SVN and IVN) of tumors, the results of the caloric tests and VEMP tests were significantly different in tumors originating from the SVN and the IVN in our study. Hearing was preserved in 16 of 26 patients (61.54%) with SVN-originating tumors, whereas hearing was preserved in only seven of 42 patients (16.67%) with IVN-originating tumors.

CONCLUSIONSOur data suggest that caloric and VEMP tests might help to identify whether VS tumors originate from the SVN or IVN. These tests could also be used to evaluate the residual function of the nerves after surgery. Using this information, we might better predict the preservation of hearing for patients.

Adult ; Female ; Hearing ; Humans ; Male ; Neuroma, Acoustic ; pathology ; physiopathology ; Vestibular Nerve ; physiology