Hearing ability according to screening at conscription; comparison with earlier reports and with previous screening results for individuals without known ear disease

Prevalence of noise-induced hearing-threshold shifts and hearing loss among US youths

OBJECTIVE

We investigated trends in noise-induced threshold shifts (NITSs), high-frequency hearing loss (HFHL), and low-frequency hearing loss (LFHL).

METHODS

A total of 4310 adolescents 12 to 19 years of age completed audiometric testing during National Health and Nutrition Examination Surveys in 1988-1994 and 2005-2006. NITS criteria were audiometric patterns of decreased 3- to 6-kHz thresholds but preserved 0.5- to 1-kHz and 8-kHz thresholds; HFHL and LFHL criteria were high and low pure-tone averages, respectively, of >15 dB HL.

RESULTS

There were no significant increases in NITSs (odds ratio [OR]: 0.81 [95% confidence interval [CI]: 0.53-1.22]; P = .29), HFHL (OR: 1.21 [95% CI: 0.87-1.69]; P = .25), or LFHL (OR: 1.37 [95% CI: 0.77-2.45]; P = .28) between survey periods. However, a significant increase in the prevalence of NITSs occurred among female youths (11.6% [95% CI: 9.0%-14.1%] vs 16.7% [95% CI: 13.2%-20.3%]; P < .0001). The overall prevalence of exposure to loud noise or listening to music through headphones in the previous 24 hours increased from 19.8% (95% CI: 17.6%-22.1%) to 34.8% (95% CI: 31.0%-38.5%; P < .0001). In 2005-2006, female youths had a similar prevalence of exposure to recreational noise (23.6% [95% CI: 19.6%-27.6%] vs 27.7% [95% CI: 23.6%-31.8%]; P < .0001) and a lower prevalence of hearing-protection use (3.4% [95% CI: 1.6%-5.3%] vs 10.3% [95% CI: 7.3%-13.2%]; P < .0001) compared with male youths.

CONCLUSIONS

Increased exposure to recreational noise and minimal use of hearing protection might have lead to an increase in NITS prevalence among female youths.

Self-assessed auditory symptoms, noise exposure, and measured auditory function among healthy young Swedish men

The aim of the study was to estimate the prevalence of the exposure to ototraumatic factors and auditory symptoms, and to analyse the relations between these factors in a group of young healthy men. A total of 839 men, 19-22 years old, were recruited for the study when reporting for primary military service. A questionnaire was distributed and audiometry was performed. The prevalence of tinnitus, sensitivity to noise, and measured hearing impairment in the study group was 23.2%, 15.5%, and 14.5% respectively. Exposure to occupational noise often was reported by 21.4%, and playing loud music often by 16.5%. The young men who had experienced tinnitus after noise exposure had an elevated risk of high frequency hearing impairment, tinnitus, and sensitivity to noise. Those who played loud music had elevated prevalence values of tinnitus but not of hearing impairment. In this young group we observed high prevalence values of ototraumatic factors and auditory symptoms. We also observed significant correlations between tinnitus after noise exposure, self-assessed hearing symptoms, and hearing impairment.

Hearing loss in relation to educational attainment and cognitive abilities: A population study

Severe hearing loss among children has often been found to be associated with educational disadvantage and lower-than-average performance on cognitive tests, but less is known about the much more widespread milder levels of hearing loss. In a cohort of 22 162 young Danish men appearing before the draft board, about 75% had normal hearing at 20 dB, and about 20% had mild hearing loss not worse than 25 dB in both ears for all tones less than 3000 Hz, and not worse than an average of 45 dB in both ears for all tones above 2000 Hz. The remaining 5% had more severe hearing loss. The proportions who had continued school education after age 16 years among the three groups were 51%, 42% and 34% respectively and their mean IQs were 101, 98 and 94. The evidence suggests that even mild hearing loss is associated with distinct educational and cognitive disadvantage which itself may result from difficulties in following classroom teaching.

Prevalence of hearing loss among 18-year-old Swedish men during the period 1971-1995

AIMS

To study the hearing of 18-year-old men by using screening audiograms obtained at military conscription.

METHODS

The study group comprised 301,873 Swedish men belonging to six age cohorts born from 1953 to 1977 who had been screened at age 18 years from 1971 to 1995. The prevalence of mild to moderate hearing loss was investigated.

RESULTS

Of the entire study group, 13.1% had elevation of one or more pure tone thresholds. In most cases, 11.9%, the elevation was situated in the high-frequency region. High-frequency hearing loss was more common in the left ear (7.5%) than in the right ear (6.2%). The prevalence of hearing loss decreased during the period 1971 to 1981 from 15.7% to 8.3%. During the last part of the study period, 1986 to 1995, the prevalence increased from 9.8% to 16.3%. The increase included mild to moderate degrees of hearing loss with thresholds below 35 dB HL. The prevalence of threshold elevations was highest in sparsely populated areas of Sweden and lowest in large, metropolitan areas of Sweden from 1971 to 1986. During the last part of the study period the geographical differences decreased or disappeared.

CONCLUSIONS

The total prevalence of hearing loss was in accordance with other reports. The frequency 6 kHz was most affected by threshold elevations. The prevalence of hearing loss decreased in the first part of the study period, and increased at the end of the study period. Hearing loss was most commonly seen in rural areas.