TABLE 9.
Prevalence of Audiometric Notch Among Working Canadians, Aged 16 to 79 Years: Occupational Noise Exposure Duration, Noise Sources, and Hearing Protection Usage
| §Notch (n = 3,431) | ||Notch (n = 3,431) | |||||||||||||
| 95% CI | 95% CI | |||||||||||||
| Characteristics | n | N | % | SE % | From | To | n | N | % | SE % | From | To | ||
| Occupational characteristics | ||||||||||||||
| Currently working in a noisy environment | ||||||||||||||
| Yes | 130 | 1,135 | 33.3 | 4.2 | 24.7 | 43.2 | *e | 88 | 516 | 15.2 | 3.5 | 8.9 | 24.7 | e,E |
| No† | 539 | 4,417 | 20.2 | 1.9 | 16.4 | 24.6 | 305 | 2,595 | 11.9 | 1.3 | 9.3 | 15.0 | ||
| Ever worked in a noisy environment | ||||||||||||||
| Yes | 348 | 2,781 | 26.0 | 2.9 | 20.2 | 32.8 | 224 | 1,770 | 16.6 | 2.0 | 12.6 | 21.5 | ‡ | |
| No† | 321 | 2,771 | 19.0 | 1.8 | 15.4 | 23.2 | 169 | 1,342 | 9.2 | 0.9 | 7.4 | 11.4 | ||
| Time worked in noisy environment | ||||||||||||||
| <12 months | 65 | 377 | 14.7 | 3.4 | 8.7 | 23.8 | ‡ e,E | f,F | ||||||
| 1 year to <5 years | 94 | 858 | 26.9 | 4.4 | 18.4 | 37.6 | E | 57 | 556 | 17.4 | 4.1 | 10.1 | 28.4 | e,F |
| 5 years to <10 years | 52 | 575 | 33.0 | 5.9 | 21.5 | 46.9 | e,E | f,F | ||||||
| 10 years or more† | 136 | 970 | 30.3 | 4.2 | 21.9 | 40.3 | 104 | 706 | 22.1 | 3.1 | 16.1 | 29.5 | e | |
| Used hearing protection at work | ||||||||||||||
| Always/often† | 138 | 1,209 | 30.2 | 4.9 | 20.5 | 42.0 | e | 89 | 760 | 19.0 | 4.7 | 10.7 | 31.3 | e,E |
| Sometimes/rarely/never | 209 | 1,568 | 23.5 | 2.7 | 18.1 | 29.8 | 135 | 1,010 | 15.1 | 1.6 | 11.9 | 19.0 | ||
| Hearing protection required/used | ||||||||||||||
| Yes/yes | 104 | 997 | 33.9 | 6.7 | 21.1 | 49.7 | e,E | 62 | 613 | 20.9 | 6.1 | 10.4 | 37.4 | e,E |
| Yes/no† | 32.9 | 10.9 | 14.2 | 59.2 | f,E | f,F | ||||||||
| No/yes | 19.2 | 6.4 | 8.8 | 36.9 | f,E | f,F | ||||||||
| No/no | 166 | 1,292 | 22.7 | 2.7 | 17.2 | 29.2 | 113 | 832 | 14.6 | 1.9 | 10.8 | 19.4 | ||
| Job category | ||||||||||||||
| White collar | 324 | 2,968 | 22.8 | 2.5 | 17.9 | 28.7 | * | 175 | 1,449 | 11.1 | 1.6 | 8.1 | 15.1 | ‡ |
| Blue collar† | 141 | 1,119 | 35.2 | 4.4 | 26.2 | 45.4 | e | 97 | 776 | 24.4 | 3.4 | 17.8 | 32.5 | e |
| Source of loud work noise | ||||||||||||||
| Machinery/transport | ||||||||||||||
| Yes | 281 | 2,416 | 27.8 | 3.3 | 21.2 | 35.6 | 191 | 1,581 | 18.2 | 2.2 | 13.8 | 23.7 | * | |
| No† | 67 | 366 | 18.2 | 3.9 | 11.1 | 28.5 | e,E | 9.4 | 2.8 | 4.7 | 17.7 | f,E | ||
| Music/people | ||||||||||||||
| Yes | 54 | 409 | 20.7 | 5.1 | 11.7 | 34.1 | e,E | 20 | 136 | 6.9 | 2.0 | 3.6 | 12.9 | ‡ e,E |
| No† | 294 | 2,372 | 27.2 | 3.6 | 20.1 | 35.7 | 204 | 1,634 | 18.7 | 2.5 | 13.9 | 24.8 | ||
| Other (munitions and/or other unspecified) | ||||||||||||||
| Yes | 20.9 | 5.2 | 11.7 | 34.6 | f,E | 17.2 | 5.0 | 8.7 | 31.2 | f,E | ||||
| No† | 307 | 2,543 | 26.6 | 3.1 | 20.4 | 33.9 | 198 | 1,574 | 16.5 | 2.0 | 12.5 | 21.4 | ||
Any hearing loss: FFPTA and/or HFPTA and/or LFPTA.
e, E use with caution (coefficient of variation 16.6–33.3%), population size and %, respectively.
f, F too unreliable to be published (coefficient of variation greater than 33.3%), population size and %, respectively.
DPOAE, distortion product otoacoustic emissions; FFPTA, four-frequency pure tone average over frequencies (0.5, 1, 2, and 4 kHz); HFPTA, high-frequency pure tone average over frequencies (3, 4, 6, and 8 kHz); LFPTA, low-frequency pure tone average over frequencies (0.5, 1, and 2 kHz).
*, ‡ significantly different from estimate for reference category (P < 0.05) and (P < 0.01), respectively.
†Reference category.
Audiometric notch definitions:
§Criteria for audiometric notch 1: (1) thresholds at 0.5 and 1 kHz of ≤15 dB, (2) maximal threshold at 3, 4, or 6 kHz ≥15 dB higher than the highest threshold for 0.5 and 1 kHz, and (3) threshold at 8 kHz ≥10 dB lower (better than) the maximal threshold for 3, 4, or 6 kHz. (Niskar et al46)
||Criteria for audiometric notch 2: thresholds at 2 and 8 kHz were both minimally at hearing levels 10-dB lower (better than) the threshold at 4 kHz (Wilson45).