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Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive multiple congenital malformation and intellectual disability syndrome resulting from variants in DHCR7. Auditory characteristics of persons with SLOS have been described in limited case reports but have not been systematically evaluated. The objective of this study is to describe the auditory phenotype in SLOS. Age- and ability-appropriate hearing evaluations were conducted on 32 patients with SLOS. A subset of 21 had auditory brainstem response testing, from which an auditory neural phenotype is described. Peripheral or retrocochlear auditory dysfunction was observed in at least one ear of 65.6% (21) of the patients in our SLOS cohort. The audiometric phenotype was heterogeneous and included conductive, mixed, and sensorineural hearing loss. The most common presentation was a slight to mild conductive hearing loss, although profound sensorineural hearing loss was also observed. Abnormal auditory brainstem responses indicative of retrocochlear dysfunction were identified in 21.9% of the patients. Many were difficult to test behaviorally and required objective assessment methods to estimate hearing sensitivity. Individuals with SLOS are likely to have hearing loss that may impact communication, including speech and language development. Routine audiologic surveillance should be conducted to ensure prompt management of hearing loss., (© 2021 Wiley Periodicals LLC.)

Objectives/hypothesis: The variability in speech perception between cochlear implant users is thought to result from the degeneration of the auditory nerve. Degeneration of the auditory nerve, histologically assessed, correlates with electrophysiologically acquired measures, such as electrically evoked compound action potentials (eCAPs) in experimental animals. To predict degeneration of the auditory nerve in humans, where histology is impossible, this paper reviews the correlation between speech perception and eCAP recordings in cochlear implant patients., Data Sources: PubMed and Embase., Review Methods: We performed a systematic search for articles containing the following major themes: cochlear implants, evoked potentials, and speech perception. Two investigators independently conducted title-abstract screening, full-text screening, and critical appraisal. Data were extracted from the remaining articles., Results: Twenty-five of 1,429 identified articles described a correlation between speech perception and eCAP attributes. Due to study heterogeneity, a meta-analysis was not feasible, and studies were descriptively analyzed. Several studies investigating presence of the eCAP, recovery time constant, slope of the amplitude growth function, and spatial selectivity showed significant correlations with speech perception. In contrast, neural adaptation, eCAP threshold, and change with varying interphase gap did not significantly correlate with speech perception in any of the identified studies., Conclusions: Significant correlations between speech perception and parameters obtained through eCAP recordings have been documented in literature; however, reporting was ambiguous. There is insufficient evidence for eCAPs as a predictive factor for speech perception. More research is needed to further investigate this relation. Laryngoscope, 2016 127:476-487, 2017., (© 2016 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives/hypothesis: To evaluate the correlation between a narrow bony cochlear nerve canal (BCNC) and facial nerve stimulation (FNS) after cochlear implantation (CI) and their underlying mechanisms and to predict the risk of FNS preoperatively., Study Design: Retrospective cohort study., Methods: A total of 64 pediatric cases that underwent CI were included. Among them, 32 cases experienced FNS after CI, and another 32 cases were selected from 817 pediatric implantees by stratified random sampling. The width of the BCNC, the status of the cochlear nerve (CN) and the internal auditory canal (IAC), T level, and C level were compared and analyzed. Strategies for eliminating FNS were also analyzed., Results: The FNS group showed a narrower BCNC (1.09 ± 0.52 mm) than the control group (1.99 ± 0.61 mm; P < .01), a lower CN/facial nerve ratio (0.32 ± 0.36) than the control group (1.34 ± 0.76; P < .01), and narrower IAC diameter (4.06 ± 1.71 mm) than the control group (5.66 ± 1.36 mm; P < .01). The FNS group also showed higher T level (165.7 ± 28.3 μA) than the control group (142.2 ± 21.2 μA; P < .01). Adjustment of the C levels and/or pulse width and switching off offending electrodes were attempted to eliminate FNS, with a 75.0% success rate. The FNS group still showed low Categories of Auditory Performance scores (3.00 ± 1.90) compared with the control group (5.94 ± 1.41, P < .01) after adjustment., Conclusions: A narrow BCNC could be a cause of FNS after CI. Therefore, careful selection of the side for CI and programming strategies are required to reduce FNS., Level of Evidence: 4. Laryngoscope, 126:1433-1439, 2016., (© 2015 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives/hypothesis: To examine the relationship between bony cochlear nerve canal (BCNC) width, degree of hearing loss, and speech discrimination in children with unilateral sensorineural hearing loss (USNHL)., Study Design: Retrospective chart review (case-control study)., Methods: Audiometric database was cross-referenced with radiologic database at pediatric tertiary care facility to identify children with USNHL and temporal bone computed tomography. BCNC widths were measured independently by two radiologists blinded to affected ear. Regression analyses investigated associations among variables., Results: One hundred and sixty children with USNHL had temporal bone imaging. Mean BCNC width was significantly smaller in affected ears, P = 0.0001. Narrower width was associated with more severe hearing loss, P = 0.01. Among children who had narrower cochlear nerve canals in affected ears compared to unaffected ears, smaller width was associated with lower speech discrimination score, P = 0.03. Increasing asymmetry in BCNC width between affected and unaffected ears was associated with poorer discrimination scores, P = 0.02. Among ears with asymmetrically smaller cochlear nerve canals, a 1-mm reduction in cochlear canal width between the normal and affected ear was associated with 30.4% lower word recognition score percentage in the affected ear, P = < 0.001., Conclusion: There is a significant association between BCNC stenosis and impaired speech discrimination, independent of degree of hearing loss. Further investigation is needed to determine whether BCNC stenosis is a poor prognostic factor for auditory rehabilitation., (© 2014 The American Laryngological, Rhinological and Otological Society, Inc.)

Objectives/hypothesis: The possibility that long-term mobile phone use increases the incidence of astrocytoma, glioma and acoustic neuroma has been investigated in several studies. Recently, our group showed that direct exposure (in a surgical setting) to cell phone electromagnetic fields (EMFs) induces deterioration of auditory evoked cochlear nerve compound action potential (CNAP) in humans. To verify whether the use of Bluetooth devices reduces these effects, we conducted the present study with the same experimental protocol., Study Design: Randomized trial., Methods: Twelve patients underwent retrosigmoid vestibular neurectomy to treat definite unilateral Ménière's disease while being monitored with acoustically evoked CNAPs to assess direct mobile phone exposure or alternatively the EMF effects of Bluetooth headsets., Results: We found no short-term effects of Bluetooth EMFs on the auditory nervous structures, whereas direct mobile phone EMF exposure confirmed a significant decrease in CNAPs amplitude and an increase in latency in all subjects., Conclusions: The outcomes of the present study show that, contrary to the finding that the latency and amplitude of CNAPs are very sensitive to EMFs produced by the tested mobile phone, the EMFs produced by a common Bluetooth device do not induce any significant change in cochlear nerve activity. The conditions of exposure, therefore, differ from those of everyday life, in which various biological tissues may reduce the EMF affecting the cochlear nerve. Nevertheless, these novel findings may have important safety implications., (© 2013 The American Laryngological, Rhinological and Otological Society, Inc.)

In adult mammals a single exposure to loud noise can damage cochlear hair cells and initiate subsequent episodes of degeneration of axonal endings in the cochlear nucleus (CN). Possible mechanisms are loss of trophic support and/or excitotoxicity. Fibroblast growth factor 2 (FGF2), important for development, might be involved in either mechanism. To test this hypothesis, we noise-exposed FGF2 overexpressor mice and observed the effects on synaptic endings by immunolabelling for SV2, a synaptic vesicle protein, at 1, 2, 4, and 8 weeks after noise exposure. SV2 staining was observed in two major locations; perisomatic, representing axo-somatic terminals, and neuropil, representing axo-dendritic terminals. The wildtype (WT) lost both perisomatic and neuropil clusters with an intervening period of modest recovery for the perisomatic. In contrast, in the overexpressor, the perisomatic clusters remained unchanged after intervening periods of increase. The neuropil clusters underwent a period of initial decline, followed by a transient recovery and ultimate decline. Changes in SV2 immunostaining correlated with changes in vesicular glutamate and GABA transporters at synapses and, in the overexpressor, with staining changes for FGF2 and FGF receptor 1. These molecules may contribute to the synaptic reorganization after noise damage; they may protect and/or aid recovery of synapses after overstimulation.

Here we characterized the relationship between duration of sensorineural hearing loss and the response of the auditory nerve to electrical stimulus rate. Electrophysiological recordings were made from undeafened guinea pigs and those ototoxically deafened for either 5 weeks or 6 months. Auditory neuron survival decreased significantly with the duration of deafness. Extracellular recordings were made from auditory nerve fibres responding to biphasic, charge-balanced current pulses delivered at rates of 20 and 200 pulses/s via a monopolar scala tympani stimulating electrode. The response to 20 pulses/s electrical stimulation of the deafened cochlea exhibited a decrease in spike latency, unaltered temporal jitter and unaltered dynamic range (of nerve firing rate against stimulus current), and a reduction in threshold after 6 months of deafness. The response to a 200-pulse/s stimulus was similar except that the dynamic range was greater than with 20 pulses/s and was also greater in deafened animals than in undeafened animals. Deafness and pulse rate are related; in deaf animals spike recovery appears to be complete between successive stimulus pulses at a low rate (20 pulses/s), but incomplete between pulses at a moderate pulse rate (200 pulses/s). These results suggest that changes in the function of individual auditory nerve fibres after deafness may affect clinical responses during high-rate stimulation such as that used in contemporary speech processing strategies, but not during lower rate stimulation such as that used to record evoked potentials.

The goals were to study the physiological effects of auditory nerve myelinopathy in chinchillas and to test the hypothesis that myelin abnormalities could account for auditory neuropathy, a hearing disorder characterized by absent auditory brainstem responses (ABRs) with preserved outer hair cell function. Doxorubicin, a cytotoxic drug used as an experimental demyelinating agent, was injected into the auditory nerve bundle of 18 chinchillas; six other chinchillas were injected with vehicle alone. Cochlear microphonics, compound action potentials (CAPs), inferior colliculus evoked potentials (IC-EVPs), cubic distortion product otoacoustic emissions and ABRs were recorded before and up to 2 months after injection. Cochleograms showed no hair cell loss in any of the animals and measures of outer hair cell function were normal (cubic distortion product otoacoustic emissions) or enhanced (cochlear microphonics) after injection. ABR was present in animals with mild myelin damage (n = 10) and absent in animals with severe myelin damage that included the myelin surrounding spiral ganglion cell bodies and fibers in Rosenthal's canal (n = 8). Animals with mild damage had reduced response amplitudes at 1 day, followed by recovery of CAP and enhancement of the IC-EVP. In animals with severe damage, CAP and IC-EVP thresholds were elevated, amplitudes were reduced, and latencies were prolonged at 1 day and thereafter. CAPs deteriorated over time, whereas IC-EVPs partially recovered; latencies remained consistently prolonged despite changes in amplitudes. The results support auditory nerve myelinopathy as a possible pathomechanism of auditory neuropathy but indicate that myelinopathy must be severe before physiological measures are affected.

Loss of cochlear hair cells in the rat initiates degenerative change within the primary auditory neurons (ANs) of the cochlea. These degenerative changes include loss of peripheral processes, demyelination and ultimately cell death. This pathology will affect the biophysical processes involved in action potential generation and propagation to an electrical stimulus via a cochlear implant. We measured the response properties of ANs, with particular reference to their refractory behaviour, in normal, short- (9 weeks) and long-term (> 52 weeks) deafened rats. AN loss was moderate in the short-term and severe in the long-term deafened animals. AN activity was elicited using a brief electrical stimulus delivered via a bipolar electrode array implanted into the cochlea. The general response properties of ANs recorded from deafened cochleae were similar to those observed in normal cochleae, i.e. a monotonic increase in the probability of firing and a decrease in response latency and temporal jitter with increasing stimulus intensity. However, the absolute refractory period was significantly prolonged in animals deaf for > 12 months (P = 0.0026). Deafened animals also exhibited a highly significant increase in threshold compared with normal controls (P < 0.001). These functional changes have implications for recipients of cochlear implants and potential therapies directed toward halting or reversing AN pathology.

We described a patient with progressive non-syndromic hearing loss (NSHL) harboring the A3243G mutation in the mitochondrial DNA (mtDNA). Muscle biopsy showed scattered ragged-red, cytochrome c oxidase negative fibers, whereas the biochemical analysis of the mitochondrial respiratory chain complexes was normal. Restriction fragment length polymorphism (RFLP) analysis showed A3243G mtDNA transition, present at very low in patient's muscle (3%) and in urinary sediments (1%), and not detectable in blood and buccal mucosa. The patient was submitted to a bilateral cochlear implantation with post-operative excellent hearing and communicative outcomes. Our findings indicate that A3243G mutation may be responsible both for SHL and NSHL, may be depending on the levels of mutated mtDNA. Patients with hearing loss due to mtDNA mutations should be considered as good candidates for cochlear implantation.

Objectives/hypothesis: Auditory neuropathy is a sensorineural hearing disorder characterized by absent or abnormal auditory brainstem responses and normal cochlear outer hair cell function as measured by otoacoustic emission recordings. Many risk factors are thought to be involved in its etiology and pathophysiology. Four Chinese pedigrees with familial auditory neuropathy were presented to demonstrate involvement of genetic factors in the etiology of auditory neuropathy., Study Design: Probands of the above-mentioned pedigrees, who had been diagnosed with auditory neuropathy, were evaluated and followed in the Department of Otolaryngology-Head and Neck Surgery, China People Liberation Army General Hospital (Beijing, China). Their family members were studied, and the pedigree maps established., Methods: History of illness, physical examination, pure-tone audiometry, acoustic reflex, auditory brainstem responses, and transient evoked and distortion-product otoacoustic emissions were obtained from members of these families. Some subjects received vestibular caloric testing, computed tomography scan of the temporal bone, and electrocardiography to exclude other possible neuropathic disorders., Results: In most affected patients, hearing loss of various degrees and speech discrimination difficulties started at 10 to 16 years of age. Their audiological evaluation showed absence of acoustic reflex and auditory brainstem responses. As expected in auditory neuropathy, these patients exhibited near-normal cochlear outer hair cell function as shown in distortion product otoacoustic emission recordings. Pure-tone audiometry revealed hearing loss ranging from mild to profound in these patients. Different inheritance patterns were observed in the four families. In Pedigree I, 7 male patients were identified among 43 family members, exhibiting an X-linked recessive pattern. Affected brothers were found in Pedigrees II and III, whereas in pedigree IV, two sisters were affected. All the patients were otherwise normal without evidence of peripheral neuropathy at the time of writing., Conclusion: Patients with characteristics of nonsyndromic hereditary auditory neuropathy were identified in one large and three smaller Chinese families. Pedigree analysis suggested an X-linked, recessive hereditary pattern in one pedigree and autosomal recessive inheritances in the other three pedigrees. The phenotypes in the study were typical of auditory neuropathy; they were transmitted in different inheritance patterns, indicating clinical and genetic heterogeneity of this disorder. The observed inheritance and clinical audiological findings are different from those previously described for nonsyndromic low-frequency sensorineural hearing loss. This information should facilitate future molecular linkage analyses and positional cloning for the relative genes contributing to auditory neuropathy.

Stereocilia are specialized actin-filled, finger-like processes arrayed in rows of graded heights to form a crescent or W-shape on the apical surface of sensory hair cells. The stereocilia are deflected by the vibration of sound, which opens transduction channels and allows an influx of ions to depolarize the hair cell, in turn triggering synaptic activity. The specialized morphology and organization of the stereocilia bundle is crucial in the process of sensory transduction in the inner ear. However, we know little about the development of stereocilia in the mouse and few molecules that are involved in stereocilia maturation are known. We describe here a new mouse mutant with abnormal stereocilia development. The Tasmanian devil (tde) mouse mutation arose by insertional mutagenesis and has been mapped to the middle of chromosome 5. Homozygotes show head-tossing and circling and have raised thresholds for cochlear nerve responses to sound. The gross morphology of the inner ear was normal, but the stereocilia of cochlear and vestibular hair cells are abnormally thin, and they become progressively disorganized with increasing age. Ultimately, the hair cells die. This is the first report of a mutant showing thin stereocilia. The association of thin stereocilia with cochlear dysfunction emphasizes the critical role of stereocilia in auditory transduction, and the discovery of the Tasmanian devil mutant provides a resource for the identification of an essential molecule in hair cell function.

Objectives: To objectify the effects of retrocochlear disease on distortion-product otoacoustic emissions (DPOAEs) by developing a computer-based software strategy for classifying DPOAE patterns as cochlear or noncochlear and to evaluate the sensitivities of these techniques in a large series of patients with unilateral acoustic neuromas., Study Design: Development of a novel, software-based method of DPOAE analysis, which was evaluated with data obtained from a retrospective review of the results from audiometric tests performed in a series of patients., Methods: A computer-based software strategy was developed, using frequency-specific data from normal-hearing adults, for the purpose of distinguishing cochlear from noncochlear patterns of hearing loss, by determining the discrepancies between DPOAEs and behavioral audiometry. Preoperative pure-tone thresholds and DPOAEs from 97 patients with surgically confirmed acoustic neuroma were compared using an objective method and a standard, subjective technique that was considered to be the gold standard. The effects of bilateral hearing losses, such as noise-induced hearing loss and presbycusis, were accounted for during the analysis to isolate the effects of the tumors on hearing thresholds and DPOAEs., Results: Overall, 55 (57%) of the tumor ears were assigned to the cochlear group (i.e., DPOAEs consistent with hearing thresholds), 40 (41%) to the noncochlear group (i.e., DPOAEs inconsistent with hearing thresholds), and 2 (2%) to an indeterminate group, using the subjective technique for classifying DPOAEs. There was no significant difference in the categorization of the patients with acoustic neuroma when employing the objective strategy. The objective algorithm, when modified to maximize the number of noncochlear identifications, led to assignments of 36 (37%) to the cochlear, 57 (59%) to the noncochlear, and 4 (4%) to the indeterminate categories., Conclusions: Subjective analysis of a large series patients with acoustic neuromas showed that the majority of ears with tumors demonstrated cochlear (57%), rather than non-cochlear (41%), patterns of DPOAEs. The computerized, software-based algorithm developed for differentiating cochlear from noncochlear patterns of DPOAEs in patients with retrocochlear disease had a maximum sensitivity of 59%. This value was significantly higher than that reported in previous studies.

Unilateral removal of Scarpa's ganglion and neurectomy of the peripheral vestibular nerve branches were compared in rats as methods to eliminate primary vestibular input. Ocular nystagmus was consistently observed after both types of lesion, but it completely disappeared within 4 to 7 days. Imbalance and rotation were more serious and prolonged after ganglionectomy than after peripheral neurectomy. Corresponding with these differences in symptoms were differences in terminal degeneration. After ganglionectomy, degenerated axons and terminals were distributed throughout all terminal regions of primary vestibular fibers on the lesioned side, while after peripheral neurectomy, the degeneration was more limited. The results of this study suggest that vestibular ganglionectomy is a more successful approach than peripheral vestibular neurectomy for removing the primary vestibular input.

The present study was undertaken to systematically examine and characterize pathological changes in vestibular nerve specimens obtained at surgery in patients with symptomatic cochleovestibular nerve compression syndrome (CNCS). Vestibular nerves were obtained in six cases of CNCS and were intermingled with vestibular nerves obtained in cases of Meniere's disease. All of the nerve specimens were coded and reviewed microscopically in a blind-study fashion by the neuropathologist. The vestibular nerves obtained from CNCS cases showed significant endoneurial fibrosis, compared to controls (specimens from patients with Meniere's disease). Based on observations in this study, as well as the clinical symptoms and audiovestibular test findings in these patients, a theory of pathophysiology in CNCS of the cochleovestibular nerve is proposed. The implications of this theory are discussed with respect to the diagnosis of CNCS.

Cochleovestibular nerve compression syndrome (CNCS) is the term used to describe a group of audiovestibular symptoms thought to be due to a vessel compressing the cochleovestibular nerve. These symptoms include recurrent vertigo, continuous disequilibrium and acquired motion intolerance. Recently, Moller reported that CNCS can be diagnosed based on abnormalities in the auditory brainstem response (ABR). After specifically excluding all other vestibular disorders, 63 patients with symptoms suggestive of CNCS were identified. These patients were systematically evaluated with a standard neurotologic test battery, and the results were reviewed retrospectively. Hearing loss was found in 51 (81%) of 63 cases, including 33 cases of unilateral high-frequency loss and 14 cases of middle-frequency loss. ABR data were interpreted with respect to Moller's criteria, and abnormal studies were found in 42 (75%) of 56 cases. Abnormal electronystagmograms were found in 57 (93%) of 61 cases. Thirteen of the patients subsequently underwent a posterior fossa procedure for vertigo and, vessels were found in contact with the cochleovestibular nerve in 11 of 13 cases. The results of this study suggest that the majority of CNCS patients have neurotologic test findings that suggest an abnormality of the cochleovestibular nerve. The results and their implications are discussed.

Unlike the eventual resolution of facial paralysis in most patients with intact facial nerves, delayed hearing return after acoustic tumor resection is rare. This discrepancy in recovery has been ascribed to the inherent resilience of the facial nerve (a special visceral efferent nerve) to injury versus the cochlear nerve (a special somatic afferent nerve). In the presence of an intact cochlear nerve, hearing loss has been attributed to transection or spasm of the internal auditory artery or to direct mechanical trauma to the cochlear nerve during manipulation of the tumor. The possibility of a reversible conduction block in the cochlear nerve has not been considered. A review of three instances of delayed spontaneous hearing recovery several months after acoustic tumor resection suggests that a conduction block phenomenon can exist. This report describes the pathophysiology and the possible intraoperative predisposing features of this condition.

Degeneration of the cochlear nerve before and after placement of the cochlear implant might influence the efficacy of the device. We examined histological characteristics, including the caliber of the cochlear nerve fibers of the central segment proximal to the porus acusticus, in three profoundly deaf patients. Two of them used a cochlear implant for many years longer in one ear than in the other, and one used an implant in one ear only. No qualitative or quantitative differences between the two sides were found. However, in all three cases we found that the cochlear nerves on both sides were substantially degenerated. These results indicated no noticeable effects of stimulation by the cochlear implant on the central portion of the cochlear nerve.

Although tinnitus severely afflicts 7.2 million Americans, the pathophysiology of this problem remains obscure because there presently exists no good animal model in which to study the phenomenon. We have examined changes in activity in the guinea pig auditory pathway using an autoradiographic method of functional brain mapping after short-term and long-term cochlear ablations which can, in humans, initiate the occurrence of tinnitus. With this method we have observed a reduction in activity in various nuclei in the auditory pathway between 4 hrs and 10 days after unilateral cochlear ablation. In contrast to these findings we have found a return of activity in these same nuclei if they are observed from 12 to 48 days following the lesion. These preliminary data suggest that this return of activity in the absence of sensory input may be a valid experimental analogue for tinnitus in humans. Such evidence for auditory plasticity may represent a significant first step toward understanding this common and profound otologic symptom.

Electrocochleography (ECoG) involves the recording of electrical responses to sound from the vicinity of the cochlea. The technique, as we practice it, utilizes a trans-tympanic recording needle situated on the promontory of the middle ear. Filtered clicks in the frequency range between 500 and 8,000 Hz are presented to the ear under test at a rate of 10/sec. Repetitive clicks of a given frequency are first presented at high intensity and the responses summed (averaged) in a computer. The click is systematically lowered in intensity, and an average is collected at each level until the normal dynamic range of hearing has been explored. Two major electrical indices are present in the recording: these are 1. the whole-nerve action potential (AP) derived from the first-order auditory neurons, and 2. the cochlear microphonic (CM) derived from the hair cells. Inspection of the whole nerve AP as intensity is lowered allows the estimation of the response threshold, which correlates well with behavioral threshold. Inspection of the relation between the CM and the AP allows qualitative differentiation to be made between pathology arising in the hair cell (sensory) and in the nerve (neural).

In disorders of the auditory organ associated with hearing loss, a correlation of the anatomical, behavioral and electrophysiological studies furnishes the investigator several parameters of study to better comprehend the hearing mechanism and the various anatomical structural dysfunctions that relate to the hearing loss. Mice are interesting to study because they carry several types of genes for hereditary deafness. Until recently, it was very difficult to train mice for behavioral hearing threshold testing; however, having developed such a method, the next step was to study the normal mice in these three parameters and extend the studies to mice with hereditary hearing loss. The type of mouse studied in this research was the C57/b16 strain which carries such a gene. The results of the studies indicate that the results of the behavioral and electrophysiological studies relate well to each other, and that light microscopic studies (if taken alone) do not furnish us with the actual functional capability of the structures of the inner ear. It is recommended (and it would be most valuable) that efforts should be made to collect and study human temporal bones with all three parameters of study for a better understanding of the structures of the human inner ear. Reference is made and recommendations given as to the parameters of studies while performing human electrocochleography.