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Objective: Mutations in the GJB2 gene encoding connexin 26 (Cx26) protein are a major cause for nonsyndromic autosomal recessive and sporadic deafness. However, its contribution to hearing impairment in Switzerland remains undefined. To determine the frequency and type of GJB2 mutations in the Swiss hearing-impaired population diagnosed under the age of 2 yr and at 2 yr and older and to assess the effectiveness of denaturing high-performance liquid chromatography (DHPLC) in screening for mutation in GJB2. Methods: Thirty-four patients with hearing impairment underwent mutation screening of the single coding exon of GJB2 with DHPLC followed by bidirectional sequencing to identify sequence alterations. Results: GJB2 mutations were more common in children diagnosed with hearing impairment under the age of 2 yr compared to the group 2 yr and older. In patients under age 2 yr, 9 of 20 (45%) harbored 13 GJB2 mutations including a common 313del14nt mutation; four of these patients were homozygous or compound heterozygous for GJB2 mutations. In contrast, 2 of 14 patients in the 2 yr and older group (14%) had a single mutation in GJB2. The 35delG mutation was exclusively found in 5 patients under the age of 2 yr. DHPLC for mutation screening was 100% sensitive and 83% specific for detecting sequence alterations in GJB2. Conclusions: In Switzerland, GJB2 mutations are a major cause of nonsyndromic hearing impairment in children under the age of 2. Similar to other populations, GJB2 mutations are uncommon in the affected Swiss patients identified after 2 yr. Although 35delG mutation is common in the hearing-impaired children under the age of 2, it was absent in patients diagnosed with hearing impairment after the age of 2. DHPLC is a highly sensitive tool for detection of GJB2 mutations.

Measurement of transiently evoked otoacoustic emissions, elicited primarily using click stimuli, and distortion-product otoacoustic emissions is gaining prominence as a clinical technique. One proposed application is the estimation of hearing levels. In this report, several formats for describing otoacoustic emission test results obtained from adult subjects are discussed. Descriptive analyses involve comparisons of individual results with normative data obtained from a group of normally hearing adults.

The clinical value of extended high-frequency audiometry for the detection of noise-induced hearing loss has not been established conclusively. The purpose of this study was to assess the relative temporary threshold shift (TTS) in two frequency regions (conventional versus extended high frequency). In this exploratory study, pure-tone thresholds from 0.5 to 14 kHz were measured in both ears of 16 nonprofessional pop/rock musicians (mean age, 35 yr; range, 27 to 49 yr), before and after a 90-minute rehearsal session. All had experienced repeated exposures to intense sound levels during at least 5 yr of their musical careers. After the rehearsal, median threshold levels were found to be significantly poorer for frequencies from 0.5 to 8 kHz (Wilcoxon signed rank test, p

The purpose of this study was to evaluate the hearing and subjective auditory symptoms in a group of nonprofessional pop/rock musicians who had experienced repeated exposures to intense sound levels during at least 5 yr of musical activity.An evaluation of both ears in 42 nonprofessional pop/rock musicians included pure-tone audiometry in the conventional and extended high-frequency range, the measurement of uncomfortable loudness levels, and an assessment of tinnitus and hypersensitivity to sound. Exclusion criteria were (a) the occurrence of acoustic trauma, (b) excessive noise exposure during occupational activities, (c) a history of recurrent otitis media, (d) previous ear surgery, (e) a fracture of the cranium, (f) ingestion of potentially ototoxic drugs, and (g) reported hearing difficulties within the immediate family. These audiometric results were then compared with a control group of 20 otologically normal young adults with no history of long-term noise exposure.After adjusting for age and gender, relative to ISO 7029, the mean hearing threshold in the frequency range of 3 to 8 kHz was 6 dB in the musicians and 1.5 dB in the control group. This difference was statistically significant (Mann-Whitney rank sum test, p0.001). A significant difference was also observed between musicians using regular hearing protection during their activities (average 3 to 8 kHz thresholds = 2.4 dB) and musicians who never used such hearing protection (average 3 to 8 kHz thresholds = 8.2 dB), after adjusting for age and gender (Mann-Whitney rank sum test, p = 0.006). Eleven of the musicians (26%) were found to be hypersensitive to sound, and seven (17%) presented with tinnitus. Tinnitus assessment, however, did not reveal any clinically significant psychological distress in these individuals.Tinnitus and hypersensitivity to sound were observed in a significant minority within a group of nonprofessional pop/rock musicians who had experienced repeated exposure to intense sound levels over at least 5 yr but with minimal impact on their lives. Moreover, hearing loss was minimal in the subjects who always used ear protection, being only 0.9 dB higher than the control group. In contrast, hearing loss was significantly more pronounced, at 6.7 dB higher than the control group, in those musicians who never used ear protection. Continued education about the risk to hearing and the benefits of the persistent use of ear protection is warranted for musicians who are exposed frequently to intense sound levels.

The purposes of the study were: (1) To evaluate the intrasession test-retest reliability of pure-tone thresholds measured in the 0.5-16 kHz frequency range for a group of otologically healthy subjects using Sennheiser HDA 200 circumaural and Etymotic Research ER-2 insert earphones and (2) to compare the data with existing criteria of significant threshold shifts related to ototoxicity and noise-induced hearing loss.Auditory thresholds in the frequency range from 0.5 to 6 kHz and in the extended high-frequency range from 8 to 16 kHz were measured in one ear of 138 otologically healthy subjects (77 women, 61 men; mean age, 24.4 yr; range, 12-51 yr) using HDA 200 and ER-2 earphones. For each subject, measurements of thresholds were obtained twice for both transducers during the same test session. For analysis, the extended high-frequency range from 8 to 16 kHz was subdivided into 8 to 12.5 and 14 to 16 kHz ranges. Data for each frequency and frequency range were analyzed separately.There were no significant differences in repeatability for the two transducer types for all frequency ranges. The intrasession variability increased slightly, but significantly, as frequency increased with the greatest amount of variability in the 14 to 16 kHz range. Analyzing each individual frequency, variability was increased particularly at 16 kHz. At each individual frequency and for both transducer types, intrasession test-retest repeatability from 0.5 to 6 kHz and 8 to 16 kHz was within 10 dB for99% and94% of measurements, respectively. The results indicated a false-positive rate of3% in reference to the criteria for cochleotoxicity for both transducer types. In reference to the Occupational Safety and Health Administration Standard Threshold Shift criteria for noise-induced hazards, the results showed a minor false-positive rate of1% for the HDA 200.Repeatability was similar for both transducer types. Intrasession test-retest repeatability from 0.5 to 12.5 kHz at each individual frequency including the frequency range susceptible to noise-induced hearing loss was excellent for both transducers. Repeatability was slightly, but significantly poorer in the frequency range from 14 to 16 kHz compared with the frequency ranges from 0.5 to 6 or 8 to 12.5 kHz. Measurements in the extended high-frequency range from 8 to 14 kHz, but not up to 16 kHz, may be recommended for monitoring purposes.

Objective: The purposes of this study were: To determine the quantitative and qualitative changes that occur in transient-evoked otoacoustic emissions (TEOAEs) in older individuals without addressing the effect of aging alone and without correction for hearing loss of the subject selection. To investigate the clinical value of measuring TEOAEs in the routine audiological evaluation of older people reasoning that a finding of hearing loss in the presence of TEOAEs could indicate a form of presbycusis with a primary central component. Design: Click-evoked otoacoustic emissions (CEOAEs) were measured in 201 subjects without middle ear problems aged 60 yr and older (range 60 to 97 yr) who volunteered for the study because of complaints concerning their hearing. Audiological procedures included a pure-tone audiogram, modified Speech Perception in Noise test (German version : Basler Satztest), and the Hearing Handicap Inventory for the Elderly (German version). Results from ears with a pure-tone average (PTA) at 0.5, 1, and 2 kHz of ≤30 dB HL were further analyzed with respect to the presence or absence of CEOAEs. In addition, tone burst evoked otoacoustic emissions (TbOAEs) were tested in ears with responses to click stimuli. The test consisted of a paradigm used previously in our laboratory to assess superposition and suppression of frequency within the cochlea (see Xu, Probst, Harris, & Roede, 1994). Results: CEOAEs were not detectable in ears with a PTA >30 dB HL. The prevalence of CEOAEs in ears with a PTA ≤30 dB HL was 60%. Response levels decreased as hearing thresholds became poorer, but there was no apparent influence on TEOAE level due to age alone. The audiological measures from ears with and without CEOAEs and with PTAs ≤30 dB HL were similar with the exception of small between group differences at lower frequencies. The TbOAE results showed no differences in linear superposition and suppression when results were compared with those of younger subjects tested previously. Conclusions: The lower overall amplitudes of TEOAEs and the lower prevalence of 60% in comparison to results from younger subjects with normal hearing imply that cochlear changes do occur with aging. However, the preservation or loss of TEOAEs does not separate subjects with presbycusis into distinct audiological categories or handicaps. Tone burst results suggest that frequency processing within the cochlea is not affected by age alone. We conclude that TEOAEs add no relevant information in the routine clinical evaluation of elderly persons with hearing problems.

Otoacoustic emissions can be separated into two interrelated classes according to the type of eliciting stimulus. On the basis of this categorization, four discrete subtypes can be recognized that include spontaneous, transiently evoked, stimulus-frequency, and distortion-product otoacoustic emissions. Methods of recording and findings in the ears of normally hearing humans are reviewed for each emission type.