Differences In Hearing Levels Research Articles

The prevalence and expression of inherited connexin 26 mutations associated with nonsyndromic hearing loss in the Israeli population.

Connexin 26 (GJB2) mutations lead to hearing loss in a significant proportion of all populations studied so far, despite the fact that at least 50 other genes are also associated with hearing loss. The entire coding region of connexin 26 was sequenced in 75 hearing impaired children and adults in Israel in order to determine the percentage of hearing loss attributed to connexin 26 and the types of mutations in this population. Age of onset in the screened population was both prelingual and postlingual, with hearing loss ranging from moderate to profound. Almost 39% of all persons tested harbored GJB2 mutations, the majority of which were 35delG and 167delT mutations. A novel mutation, involving both a deletion and insertion, 51del12insA, was identified in a family originating from Uzbekistan. Several parameters were examined to establish whether genotype-phenotype correlations exist, including age of onset, severity of hearing loss and audiological characteristics, including pure-tone audiometry, tympanometry, auditory brainstem response (ABR), and transient evoked otoacoustic emissions (TEOAE). All GJB2 mutations were associated with prelingual hearing loss, though severity ranged from moderate to profound, with variability even among hearing impaired siblings. We have not found a significant difference in hearing levels between individuals with 35delG and 167delT mutations. Our results suggest that, in Israel, clinicians should first screen for the common 167delT and 35delG mutations by simple and inexpensive restriction enzyme analysis, although if these are not found, sequencing should be done to rule out additional mutations due to the ethnic diversity in this region.

Improved Word Perception in Tinnitus Patients Following Electrical Stimulation of the Ear: A Preliminary Report

The present study showed that there were close relationships between tinnitus relief and improved word perception by means of a grammatically correct but non-sense Japanese word perception test. Fourteen out of 20 patients reported tinnitus relief and improvement in hearing. Nine out of the 14 patients were thought to be significantly improved in word perception. Improved word perception was observed in 7 out of 10 patients whose ears tested were opposite to ears treated while in 2 out of 10 patients whose ears tested were the same as ears treated. Improved word perception was observed in 5 patients at one segment, 2 patients at two segments and 2 patients at three segments. Improved word perception was observed in one patient at the first segment, 5 patients at the second segment, 5 patients at the third segment and 5 patients at the fourth segment. There were no significant differences in hearing level nor age in patients with and without relief of tinnitus.

Gender differences in a longitudinal study of age-associated hearing loss

Current studies are inconclusive regarding specific patterns of gender differences in age-associated hearing loss. This paper presents results from the largest and longest longitudinal study reported to date of changes in pure-tone hearing thresholds in men and women screened for otological disorders and noise-induced hearing loss. Since 1965, the Baltimore Longitudinal Study of Aging has collected hearing thresholds from 500 to 8000 Hz using a pulsed-tone tracking procedure. Mixed-effects regression models were used to estimate longitudinal patterns of change in hearing thresholds in 681 men and 416 women with no evidence of otological disease, unilateral hearing loss, or noise-induced hearing loss. The results show (1) hearing sensitivity declines more than twice as fast in men as in women at most ages and frequencies, (2) longitudinal declines in hearing sensitivity are detectable at all frequencies among men by age 30, but the age of onset of decline is later in women at most frequencies and varies by frequency in women, (3) women have more sensitive hearing than men at frequencies above 1000 Hz but men have more sensitive hearing than women at lower frequencies, (4) learning effects bias cross-sectional and short-term longitudinal studies, and (5) hearing levels and longitudinal patterns of change are highly variable, even in this highly selected group. These longitudinal findings document gender differences in hearing levels and show that age-associated hearing loss occurs even in a group with relatively low-noise occupations and with no evidence of noise-induced hearing loss.

Effects of adverse perinatal events on hearing

The hearing sensitivity for frequencies 8 kHz through to 18 kHz was compared between children with adverse perinatal factors (study group) and children without adverse perinatal factors (control group). Children in both groups had hearing at levels of 20 dB HL or better in the frequency range between 250 Hz to 8 kHz with normal middle ear pressure. High frequency hearing tests showed that the mean high frequency hearing threshold levels were worse in the study group. Statistical analysis showed significant differences in hearing levels at and above 12 kHz frequencies between the study and control groups. The hearing levels were found to be more significantly affected in females as compared to males, indicating that the high frequency hearing of females was more vulnerable to damage. The results indicate that adverse perinatal events are associated with raised high frequency thresholds in both sexes, especially in females.

Hearing loss in facioscapulohumeral muscular dystrophy

The coincidence of facioscapulohumeral muscular dystrophy (FSHD) with sensorineural hearing loss and retinal abnormalities might imply genetic heterogeneity of FSHD. We performed screening audiometry in 56 patients with autosomal dominant FSHD and in 72 healthy family members, and found that the difference in hearing level between 4,000 Hz and 6,000 Hz was significantly greater in FSHD patients than in controls, independently both for the left and right ear. We conclude that this change of hearing function is part of the disease and may lead to severe hearing loss in some patients. The fact that it was present in all families is another argument against genetic heterogeneity.

Psychological dimensions in patients with disabling tinnitus and craniomandibular disorders

Forty-two patients with severe tinnitus and craniomandibular disorders (CMD) are presented from an audiological and psychological point of view. During a 2-week period, the patients rated their mood and their tinnitus. Based upon mood ratings, patients were grouped into three clusters (high, medium and low mood). The three groups differed in a number of respects, audiological as well as psychological. Patients in the low mood group experienced significantly more intense and severe tinnitus and more daily stress than patients in the high mood group. Ratings of irritation and concentration difficulties seemed to be mood related, and discriminated between patients in the low mood group and patients in the moderate and the high mood groups. Difference in hearing level between the left and the right ear was more pronounced in patients with low mood. There were, however, no significant differences between the groups in the stomatognathic variables. It is concluded that the above mentioned audiological and psychological observations should be considered as potentially important for satisfactory management of individual tinnitus patients. Further studies of the effects of optimally compensated hearing on depressed mood in patients with noise-induced hearing loss (NIHL) and tinnitus are required.

Hearing levels of railroad trainmen.

The hearing sensitivity of 9427 railroad train crew members, determined during the first year of a company-wide hearing conservation program, was compared with hearing sensitivity in a control population not exposed to occupational noise. The hearing sensitivity of the trainmen did not differ significantly from that of the control population. Multiple regression analysis, which considered separately the effects of age and years of service, showed significant differences in hearing levels due to age, but no differences in hearing levels due to years of service. Evaluation of the data by risk categories developed by the National Institute for Occupational Safety and Health indicate that this group of trainmen had no risk of occupational noise-induced hearing loss. These analyses, combined with studies of locomotive cab noise, show clearly that trainmen are not typically exposed to hazardous occupational noise.

Comparison of hearing acuity of rural, urban, and industrial populations

Auditory acuity of 104 rural individuals, 126 urban individuals not exposed to occupational noise, and 118 workers from a textile mill was examined in order to study the influence of noise exposure characteristics on hearing level of the three populations. Pure-tone audiometry in 5-dB steps at selected frequencies was conducted with the help of a portable diagnostic audiometer. Noise level recordings were made by a B&K impulse precision sound level meter and an octave band analyzer. The differences in hearing level at 4 kHz between the populations were found to be statistically significant, with the rural individuals exhibiting superior hearing capacity compared to other groups, and urban individuals showing better ability compared to their industrial counterparts. In the low frequencies (0.5 and 1 kHz), however, significant differences were observed only between rural and industrial workers. The comparison between urban and industrial workers yielded only differences in absolute values which were not significant. Some factors contributing to the poorer hearing capacity of urban individuals have been discussed. The significance of this evaluation in the context of a mass movement of individuals from rural to urban areas to seek employment has been outlined.

Extended high-frequency hearing loss in children with cleft palate.

Hearing sensitivity for frequencies 250 through 20 000 Hz was compared between children with repaired cleft palate and a history of otitis media, and children without cleft palate or middle ear disease. All subjects were clear of middle ear effusion during the evaluation. Although children in the cleft palate group had consistently poorer hearing throughout the auditory range, statistical analysis demonstrated significant differences in hearing levels above 9 000 Hz only. No statistical difference was observed for the standard clinical audiometric frequencies. Extra-high-frequency hearing loss appears to be associated with cleft palate and its sequelae.

An evaluation of hearing conservation program--a five-year longitudinal study.

The effectiveness of a hearing conservation program was investigated by analyses of changes in hearing threshold levels over a 5-year period among 2770 male employees of the DuPont Company. The study focused on 1966 men in this group whose level of noise exposure did not change during the study period. Three categories of noise levels were established. One consisted of areas in which the level was below the hearing conservation criterion, approximately 90 dBA; the other two were above that level. The mean differences in hearing levels were essentially the same in the three noise level categories, at each test frequency, and regardless of the hearing level at the beginning of the study period. We therefore concluded that a hearing conservation program whose components include periodic audiometric testing and ear protection, and which utilizes a hearing conservation criterion of approximately 90 dBA, is capable of protecting the hearing of noise-exposed workers.

Some possible effects of the delay of early treatment of deafness.

Questionnaire responses by parents of children enrolled in a school for the deaf indicated that those children who have additional learning problems superposed on their severe hearing impairment had been diagnosed as hearing-impaired, had been fitted with hearing aids, and had begun an educational program at a later age than the other children. These same children had more often been labeled “aphasic.” The difference in hearing levels between the groups of children was not enough to account for the considerable differences in early experiences. These data are interpreted as suggesting the hypothesis that sensory deprivation in hearing-impaired children resulting from delayed educational procedures and delayed sound amplification may produce an additional learning handicap which is only partly reversible by later therapeutic procedures.