Genetics of presbycusis and presbystasis.

Presbycusis and presbystasis represent relevant problems of aging, caused by the increase in life expectancy in developed countries. As such, it is advantageous to better understand the physiopathological mechanisms of these age-related inner ear diseases. The hypothesis that presbycusis and presbystasis have a genetic background was proposed some years ago. Several studies (in humans and animals) are available in the literature, and possible genes involved in the physiopathology of both diseases have been identified. The aim of this paper is to present an overview of the information available in the current medical literature on presbycusis and presbystasis.

Optimizing otoacoustic emission protocols for a UNHS program.

OBJECTIVE: To identify the optimal test protocol to screen for hearing problems in newborns, an evaluation of three distortion product otoacoustic emission (DPOAE) protocols was conducted in neonates, from a well-baby nursery (WBN) and from a neonatal intensive care unit (NICU) and compared to the performance in newborns of a more standard protocol based on transient-evoked OAEs (TEOAEs). METHODS: The DPOAE protocols used asymmetrical stimulus intensities (L(1) > L(2)) with a frequency ratio of 1.22, in the following format: (P1), L(1) = 60, L(2) = 50 dB SPL; (P2), L(1) = 65, L(2) = 55 dB SPL, and (P3), L(1) = 75, L(2) = 65 dB SPL. Linear TEOAE responses, evoked by click stimuli of 75 dB peSPL, were used as controls of normal cochlear function. Five frequencies at 1.5, 2.0, 3.0, 4.0 and 5.0 kHz were tested with a common commercially available macro-based software subroutine (Otodynamics Corp, ILO-92). The project evaluated the responses from 1200 WBN infants (average age 48 h) and 350 low-birth-weight NICU infants, all randomly selected. RESULTS: Statistical analyses comparing the signal-to-noise ratios (S/N), at the predefined f(2) frequencies, indicated that the P1 and P2 DPOAE protocols generated similar responses. Significant S/N differences were observed in the P3 to P2 dataset comparisons. DPOAE scoring criteria were estimated from the P3 dataset using a one-sided, distribution-free confidence intervals. The scoring criteria for a 'pass' were estimated as a minimum S/N of 6.0, 7.0 and 6.0 dB at 2.0, 3.0 and 4.0 kHz, respectively. In terms of feasibility, the P3 protocol generated responses in 98% of the WBN and 94.8% of the NICU infants. CONCLUSIONS: All three DPOAE protocols demonstrated shorter time-recording requirements than the standard TEOAE test. The false-positive and false-negative rates for the NICU infants were estimated as 0.0028 and 0.003%, respectively.

Neonatal newborn hearing screening: four years' experience at Ferrara University Hospital (CHEAP project): part 1.

The Child Hearing Early Assessment Programme (CHEAP) regional project, was a combined departmental approach (Audiology, Neonatology) of the University Hospital of Ferrara, aimed at identifying neonatal hearing impairment and defining early intervention strategies. Aims of this project have been: (i) construction of a neonatal screening programme using evoked otoacoustic emission and auditory brainstem responses; (ii) the calculation of a precise estimate of cost-benefits for every child tested; (iii) the development of an information flow instrument (database) for the storage of data and the statistical analysis of the results. The present report refers only to the results of the project related to the otoacoustic emission data from well-babies and intensive care unit residents. In the period January 2000-December 2004, 4269 full-term newborns and 654 Neonatal Intensive Care Unit babies were tested at the Neonatology Department. The cost of the Universal Neonatal Hearing Screening was estimated at Euro 9.20 per child, considering the use of the ILO-292 apparatus, and Euro 8.28 per child in the case of an automatic screener. In this screening model, the initial hardware costs can be re-iterated into budget in a period of two years, if 1000 children per year are tested.

Enlarged vestibular aqueduct: Audiological and genetical features in children and adolescents.

BACKGROUND: Enlarged Vestibular Aqueduct (EVA) is one of the most common congenital malformations associated with sensorineural or mixed hearing loss. The association between hearing loss and EVA is described in syndromic (i.e. Pendred Syndrome, BOR, Waardenburg) and non-syndromic disorders, as isolate or familiar mutations of the SLC26A4 gene. The audiological phenotype of the EVA syndrome is heterogeneous, the type and entity of hearing loss may vary and vertigo episodes might also be present. OBJECTIVE: The aim of this retrospective study was to describe the clinical and genetic features of a group of adolescent subjects presenting an EVA clinical profile, considering the presence of SLC26A4 gene mutations. METHODS: 14 Caucasian patients were assessed (24 ears in total; 4 patients presented a monolateral EVA), 10 females and 4 males. Their age at the time of diagnosis was between 1 and 6 years (mean age 2.5 years). Subjects were assessed by an ENT microscopy evaluation with a complete audiometric assessment, CT & MRI scans and genetic tests for the evaluation of the pendrin gene mutations (SLC26A4). RESULTS: Considering the presence of SLC26A4 mutations and thyroid function, we could identify three sub-groups of patients: group 1, non syndromic EVA (ns EVA, no SLC26A4 mutation and no thyroid dysfunction); group 2, EVA with DFNB4 (single SLC26A4 gene mutation and no thyroid dysfunction); group 3, EVA with Pendred Syndrome (two pathological mutation of SLC26A4 and thyromegaly with thyroid dysfunction). Patients of group 1 (ns-EVA) showed various degrees of hearing loss from mild (55%) to severe-profound (45%). In groups 2 (DFNB4) and 3 (PDS), the degree of hearing loss is severe to profound in 70-75% of the cases; middle and high frequencies are mainly involved. CONCLUSIONS: The phenotypic expressions associated with the EVA clinical profile are heterogeneous. From the available data, it was not possible to identify a representative audiological profile, in any of the three sub-groups. The data suggest that: (i) a later onset of hearing loss is usually related to EVA, in absence of SLC26A4 gene mutations; and (ii) hearing loss is more severe in patients with SLC26A4 gene mutations (groups 2 and 3 of this study).

Noise-induced hearing loss: a study on the pharmacological protection in the Sprague Dawley rat with N-acetyl-cysteine.

Noise-induced hearing loss is one of the most common causes of deafness and, at present, there is no treatment for the recovery of the normal hearing threshold after prolonged exposure to loud acoustic stimuli and the generation of acoustic trauma. Prolonged exposure to noise can cause oxidative stress in the cochlea which results in the loss (via apoptotic pathways) of the outer hair cells of the organ of Corti. It has been demonstrated that some antioxidant molecules, for example L-N-acetyl-cysteine, can prevent oxidative stress in the inner ear. Aim of the study was to evaluate whether L-N-acetyl-cysteine, given at various dosages, can preserve the fine structures of the cochlea from the insult of continuous noise. A series of 18 Sprague Dawley male albino rats were exposed to continuous noise (8 kHz octave band noise, 105 dB SPL, 4 hours), and cochlear functionality was evaluated by recordings of transient evoked otoacoustic emissions and distortion products otoacoustic emissions). The group which showed the best protection was that which received a total dosage of 1500 mg/kg of L-N-acetyl-cysteine. These data suggest that while L-Nacetyl-cysteine can partially protect the cochlea from continuous noise, the protection effect is strongly dose-dependent: lower dosages do not fully protect the cochlea and higher dosages can damage the rat systemically (e.g. pulmonary toxicity).

Protection against cisplatin ototoxicity in a Sprague-Dawley rat animal model.

Cisplatin (CDDP) is an anti-neoplastic drug extensively used in cases of head and neck cancer. Cisplatin induces numerous untoward side-effects including ototoxicity. In this study, cisplatin ototoxicity in Sprague-Dawley rat animal model has been evaluated and the oto-protection provided by the systemic administration of the antioxidant drug D-methionine has been tested. A total of 12 Sprague-Dawley rats were used: 8 were treated intra-peritoneally with D-methionine (300 mg/kg) and cisplatin (16 mg/kg, slow 30 min-infusion), 4 only with cisplatin. The hearing threshold of the animals was evaluated by electrophysiological procedures as Otoacoustic Emissions and Auditory Brainstem Responses. The effects of protection were evaluated after 72 hours. The data from the Otoacoustic Emissions (in the 4.0-12 kHz band) and Auditory Brainstem Responses recordings suggested that D-methionine can partially protect from Cisplatin ototoxicity.

Cochlear implant and inflammation reaction: Safety study of a new steroid-eluting electrode.

Dexamethasone is a common anti-inflammatory agent added to cochlear implants to reduce hearing loss due to electrode insertion trauma. We evaluated the safety of eluting silicone rods containing 10% dexamethasone in a Guinea pig model. Animals were implanted with a dexamethasone eluting silicone electrode (DER) or with a non-eluting electrode (NER). The control group only underwent a cochleostomy (CS). Prior to implantation and during the two weeks following implantation, the hearing status of the animals was assessed by means of Compound Action Potentials (CAPs) with an electrode placed near the round window. Two weeks after implantation, the mean click threshold shifts were 1 dB ± 10 dB in the DER group, 10 dB ± 10 dB in the NER group and -4 dB ± 10 dB in the control group. After two weeks the bullae of each animal were extracted to verify the presence of macrophages, the percent of tissue growth in the scala tympani and the tissue sealing around cochleostomy. Silicone electrodes samples were also explanted and examined for bacterial infection. Neither bacterial infection nor enhanced number of macrophages were observed. A limited, but not significant, tissue growth was found in the scala tympani between the experimental and the control group. The data suggest that, in the Guinea pig model, the use of DER is apparently safe as an anti-inflammatory slow-release additive to the cochlear implant.

Idiopathic sudden sensorineural hearing loss: cardiovascular risk factors do not influence hearing threshold recovery.

Previous studies have suggested that risk factors for ischaemic vascular disease, such as cigarette smoking, hypertension and hyperlipidaemia, can also be considered risk factors for the development of idiopathic sudden sensorineural hearing loss (ISSNHL). In this study, we have evaluated the hypothesis that these factors can influence hearing threshold recovery in patients affected by ISSNHL. A total of 141 subjects who suffered an episode of ISSNHL were included. All subjects were assessed with tonal audiometry, auditory brainstem responses and MRI to exclude retrocochlear pathology. Hearing tests were conducted at ISSNHL onset (t = 0) and after 30 days. Patients were divided into three classes according to the presence/absence of one or more cardiovascular risk factors including: history of smoking, total serum cholesterol/triglycerides, history of hypertension and diabetes mellitus. Values of hearing threshold recovery were estimated and comparisons were conducted across the three risk factor classes. 75% of patients affected by ISSNHL showed a threshold recovery. However, the threshold recovery was found to be class-independent (average recovery value of 18 dB HL per classes) and also independent of age and gender. Even if cardiovascular risk factors have been found to be involved in the pathogenesis of ISSNHL, the present study suggests that these factors do not have any significant influence on the threshold recovery in ISSNHL.

Evaluation of cisplatin ototoxicity in a rat animal model.

The ototoxic effects of cisplatin were evaluated by otoacoustic emissions and evoked auditory responses. A transient otoacoustic emissions protocol indicated no significant ototoxic effects in rats treated intravenously with 7.5 mg/kg/week for 2-weeks. A chronic 6-week treatment (2.5 mg/kg/week) monitored by 2F1-F2 distortion product emissions presented significant SNR alterations in a narrow range of frequencies (5.04-5.66 kHz). An acute treatment of 15 mg/kg, using slow 30-min intraperitoneal infusion, presented the highest DP and ABR alterations. The SNR at the 2F1-F2 frequencies 6.34, 7.13, and 7.56 kHz was found significantly decreased, and ABR latency measurements from 8-kHz burst stimuli verified these alterations.

An animal model based on the Sprague Dawley rat for the evaluation of ototoxicity.

Various methodological approaches that can be used to detect ototoxic effects caused by the administration of various substances are presented, using the Sprague-Dawley rat as an animal model. Electrophysiological data are also presented to show how the model behaves with potentially ototoxic (hyaluronic acid) and initially inert (hydroxy-propyl-methyl-cellulose) substances.

A TEOAE screening protocol based on linear click stimuli: performance and scoring criteria.

In order to improve the quality of current TEOAE recording methodologies, we have conducted a comparison of TEOAE neonatal recordings acquired with linear protocols using click stimuli of 68 dB SPL and non-linear protocols using the ILO default stimulus values. From a theoretical standpoint it was expected that the linear recordings would generate responses characterized by higher S/N ratios due to the fact that the stimulus sequence contains four clicks of the same intensity and polarity. The project included recordings from 1,416 neonatal ears (age 48 h). The TEOAE data were compared in terms of correlation, response amplitude, noise, corrected response and S/N ratio in the 1.0-, 2.0-, 3.0-, 4.0- and 5.0-kHz bands, using a paired t-test criterion. We found that windowed (4-14 ms) responses evoked by a linear TEOAE protocol generated superior S/N estimates in the 2.0-, 3.0-, 4.0- and 5.0-kHz TEOAE bands, in addition to superior correlation estimates, and demonstrated lower levels of noise. Clear-cut scoring criteria were established for the S/N ratios at 2.0, 3.0 and 4.0 kHz, by constructing one-sided distribution-free tolerance boundaries.

Efficient otoacoustic emission protocols employed in a hospital-based neonatal screening program.

Within the context of a hospital-based newborn hearing screening program, we have studied the application of two OAE protocols (TEOAE and DPOAE) on a group of 250 well babies. The main goal of this study was to evaluate the performance of DPOAE protocol in a relatively large population sample. using a preset number of five tested frequencies, in comparison with a default TEOAE screening protocol. The data were collected on the second day of life and during spontaneous sleep. The TEOAE recordings were acquired with linear protocols using click stimuli of 70-75 dB SPL and were used as indicators of normal cochlear function. The cubic distortion product DPOAE responses were evoked by an asymmetrical 75-65 dB SPL protocol, with a frequency ratio of 1.22. Five frequencies (referring to F2) were tested at 1.5, 2.0, 3.0, 4.0 and 5.0 kHz. The data from the DPOAE responses show a similar pass rate (similarity = 0.98) to the linear TEOAE protocol. The data presented suggest that a DPOAE cochlear evaluation, at 5 pre-selected frequencies, has clinical potential.

[Audioscan automatic audiometry: theoretical basis and normative data]. / Audiometria automatica Audioscan: basi teoriche e dati normativi.

Audioscan automatic audiometry is a high resolution method to explore hearing thresholds in the 125 Hz-16 KHz range offering a resolution of 64 points per octave. This procedure makes it possible to study hearing threshold levels at intermediate frequencies which are not measured by conventional audiometry. As suggested in the literature, it is possible to identify hearing threshold notches, considered indicators of mild or subclinical cochlear pathology. In clinical practice, the use of a new audiometric technique requires affirmation of reliability, sensitivity and replicability in time. It also requires defining standard criteria for use in various otologic pathologies. The present study examined 50 normal hearing subjects with conventional audiometry and Audioscan (Essilor model) measurements. A standard acquisition protocol was followed where three Audioscan measurements were conducted per subject. Subjects with a history of acute otologic pathology and familiarity for genetic deafness were ruled out of the study. Multiple, pairwise correlation analyses of the audiometric and Audioscan responses indicate that: (1) there are no significant differences between threshold levels measured by Audioscan and conventional audiometry; (2) there are no significant variations in the hearing levels measured by three Audioscan retests. Three mean indicators of the threshold level have been defined, expressing Audioscan normality in three different frequency ranges. The data suggest that there are some difficulties in the subjectivity of the Audioscan method and some technical problems regarding the lower octave frequencies and these need to be addressed. The results obtained in this study confirmed reliability of the Audioscan in the mid and high frequencies. The definition of the standard mi criteria makes it easier to interpret the Audioscan measurements from cases presenting various otologic pathologies. Therefore, the plasticity and high detection sensitivity of hearing loss make the automatic Audioscan audiometry a useful clinical tool for diagnostic and/or preventive purposes.

[Evaluation of a linear TEOAE protocol in hearing screening of neonates: feasibility study]. / Valutazione di un protocollo TEOAE lineare nello screening audiologico neonatale: studio di fattibilità.

The audiological screening of newborns based on recording TEOAEs--the expression of anatomical-functional integrity of the cochlea--has unanimously gained importance. The prevalence of severe of genetic or congenital hearing loss in the healthy infant population and in the population at risk for audiological disorders, as well as the consequent psycholinguist and socialization problems such children have to deal with, have led the authors to set up a preliminary protocol for the audiological screening of neonates. The purpose of this protocol is to improve the feasibility of applying such a program. To this purpose, the preliminary protocol called for the recording of the TEOAE in both non linear (NL) and linear (L) modes. Examination was performed in 347 newborns (30% of all the children born during 1997) the second day of life and during spontaneous sleep. The ILO 92 was used for the screening. The results obtained with the two methods were statistically compared using the 9 parameters considered response indicators. Using the linear method of a function-window and improving the signal-to-noise ratio, the study showed a significant difference in the quality of the TEOAE using the linear method as compared with the non linear method, although this did not modify response reliability. This lead to the definition, through free distribution statistical analysis, of broader than normal criteria by which to evaluate the responses evoked with the L method. All this is aimed at increasing system specificity and reducing the number of false positives which feeds family anxiety.

[Distortion product otoacoustic emission (DPOAEs) and newborn hearing screening: a feasibility and performance study]. / Otoemissioni Acustiche dei Prodotti di Distorsione (DPOAEs) e screening audiologico neonatale: studio di applicabilità e performance.

In view of the great psychological effect deafness has on one's social life, the scientific community has long sought the best way to define the hearing function. The development of new technologies in this field has set "early intervention" as the primary target for screening. For this reason, within the contest of a program of audiological newborn hearing screening, the Authors have used data from a selected group of 1250 newborns to (a) compare the clinical feasibility and performance of three different DPOAE protocols and (b) establish the scoring criteria defining "pass" or "fail" responses. All subjects participating in this study were randomly selected and their normal hearing was verified by linear TEOAE recordings. The test was carried out, using an Otodynamics ILO92 Analyser version 5.60, on the second day of life or later (in case of extended recovery), during natural sleep and after feeding. The DPOAE recordings were elicited using asymmetric stimuli with L1 > L2 and a frequency-ratio of 1.22 following three different SPL protocols: 60-50 dB (PR1), 65-55 dB (PR2) and 75-65 dB (PR3). Five frequencies of the cubic distortion product (referring to f2) were tested with an ILO macro at 1.5 KHz, 2.0 KHz, 3.0 KHz, 4.0 KHz and 5.0 KHz. The statistical evaluation of differences in the signal-to-noise ratio (S/N) between the PR1 and PR2 protocols showed no significant differences. On the other hand significant differences were found between the PR3 and the PR2 S/N ratios, the former providing the best performance (higher values). The scoring criteria were defined by minimum free distribution tolerance intervals of the S/N ratios at the five tested frequencies. In conclusion this study confirms the feasibility of DPOAE recordings in a un iversal newborn hearing screening program and shows the appropriate pass-fail parameters to be used for this purpose. It should be noted that this approach enables acquisition of frequency-specific information which might further improve audiological diagnosis.

[Cisplatin and carboplatin-induced ototoxicity in children: clinical aspects and perspectives for prevention]. / Ototossicità da cisplatino e carboplatino in età pediatrica: aspetti clinici e prospettive di prevenzione.

In 70% of the cases of malignant neoplasms in pediatric patients antiblast therapy is used. The administration of platinum compounds, Cisplatin (CDDP) or Carboplatin (CBDCA), often at high cumulative doses, necessarily implies a certain degree of toxicity which normally takes on secondary significance in the healing of the child. Among the side effects, early and delayed ototoxicity is well known and, in the child, take on particular aspects. While not abandoning the treatment of the base pathology, the therapeutic findings, increasingly comforting in terms of long-term survival, require more accurate evaluation and overall control of the quality of life of these young patients. Since initial cochlear damage can be reversible, auditory function must be carefully monitored in order to prevent the lesions from becoming permanent, in particular prior to the onset of speech. For this reason a retrospective study was made of a group of 26 children affected by malignant neoplasms all of whom had undergone a polychemotherapy protocol with the administration of CDDP in 14 cases and CBDCA in 12 cases. All these young patients were monitored with conventional audiometry. The presence of different variables (antiblastic drug administration schedule, course of the disease, general conditions) only permitted evaluation of a single correlation: between auditory function at the end of the treatment (or after a few cycles of therapy) and the overall dose of CDDP or CBDCA administered. In 16 cases (62%) typical bilateral perceptive deafness was detected progressively involving the hyperacute and acute frequencies. The finding of hearing loss was significantly greater in the patients treated with CDDP (86%) vs. those treated with CBDCA (33%). Moreover, analysis of the results showed that, within certain limits, ototoxicity can depend more on individual sensitivity to the drug than to the total dose administered. The results confirm the well-known ototoxicity of platinum compounds, in particular CDDP. As ever improved therapeutic results are achieved in the treatment of malignant neoplasms in pediatric patients, greater attention can be paid to the quality of life of these young patients after the disease has been healed. Careful monitoring of auditory function can be extremely important in the pursuit this objective; indeed, this makes it possible to adjust antiblast drug administration, particularly in the later stages of treatment, customizing the treatment schedule to individual patient sensitivity.

Identifying congenital hearing impairment: preliminary results from a comparative study using objective and subjective audiometric protocols.

To compare objective and subjective protocols assessing hearing loss in young children and evaluate frequency-specific hearing impairment through a comparison between auditory steady state responses (ASSR), auditory brainstem responses (ABR), transient otoacoustic emissions and conditioned orientation reflex responses (COR). Thirty-five hearing-impaired children (20 male and 15 female), aged between 14 months and 4 years, participated in the study. Hearing threshold levels and peripheral auditory function were assessed by measurements of ABR, ASSR, otoacoustic emissions and COR. The analysis of the COR and ASSR variables showed significant correlations in the majority of tested frequencies. The data highlight a characteristic of the COR procedure, which is an underestimation of the hearing threshold in comparison to the ASSR estimate. The data show that the COR threshold assessment follows the pattern of the other two established electrophysiological methods (ABR, ASSR). The correlation analyses did not permit evaluation of the precision of these estimates. Considering that the ASSR variables show a better relationship with ABR (higher correlation values) than COR, it might be advantageous to utilize the ASSR to gain frequency-specific information.

A comparison of audiometric and objective methods in hearing screening of school children. A preliminary study.

OBJECTIVE: In newborn hearing screening, one exclusively applies objective hearing testing methods--based on evoked potentials and/or on otoacoustic emissions. However, when testing school children, one can consider both audiometric and electrophysiological methods. The choice of methods is determined by the aims of the program. If one wants to detect conductive hearing losses, impedance audiometry seems to be the method of choice. METHODS: The aim of this study was to compare test performance measures from audiometric and objective methods (OAEs and impedance audiometry), in the hearing screening of school children. Screening protocols were applied on a group of 190 children of about 12 years of age (6th grade of primary school). RESULTS: For a single application of a screening procedure, the best performance was observed in the automated four-tone audiometry, followed by the tympanometry and the TEOAE-based procedures. Screening performance was enhanced using a combination of automated and impedance audiometry. A four-tone audiometry test combined with tympanometry gives a sensitivity of 65%, and the PPV of 46%, which are reasonable values, acceptable for practical use. The use of a TEOAE protocol degrades the overall performance of screening. CONCLUSIONS: Screening of school children is feasible with a combination of automated audiometry and tympanometry with time requirements equal to 3 min per subject.

Identification of hearing loss using TEOAE descriptors: theoretical foundations and preliminary results.

It was hypothesized that the relationship between transiently evoked otoacoustic emission (TEOAE) signals and the functional status of the outer hair cells provides an opportunity to design a clinical procedure that can evaluate the normality of cochlear function. To discriminate normal subjects from subjects suffering from mild to moderate hearing loss (HL), it was assumed that every subject population has unique and discrete TEOAE signal descriptors. The main classification algorithm was based on a discriminant analysis of raw fast Fourier transform data. When it was applied to a sample set of TEOAE recordings (from 56 normal and 68 HL subjects) elicited from 68-dB SPL click stimuli, it correctly identified 90.2% of the normal and 87.5% of the HL subjects. The same algorithm yielded an 85.5% discrimination between TEOAE recordings from conductive and cochlear HL cases.

Time-frequency analyses of TEOAE recordings from normals and SNHL patients.

This study evaluated the characteristics of transient evoked otoacoustic emission (TEOAE) time-frequency (TF) representations from normal and hearing-impaired ears. Linear and non-linear TEOAE recordings from normally-hearing subjects (40) and non-linear recordings from patients with sensorineural hearing loss (SNHL) (40) were analysed using the short-time-Fourier-transform spectrogram, the Gabor spectrogram, and the adaptive spectrogram. The TF representations of the TEOAE recordings indicated a considerable dispersion of energy across frequencies and TEOAE time segments >4.0 ms. The linear and non-linear recordings from the normal subjects showed common frequency peaks. The TF representations from the patients with SNHL indicated that the significantly reduced energy in the mid-to-high TEOAE frequencies did not correlate closely with the threshold elevation. As in the recordings from the normal subjects, a high percentage of the TEOAE cumulative energy was found within a short TEOAE segment (4-14 ms).