Hearing loss (better ear) and prevalence of audiometric notches (worse ear) and NIHL (worse ear) in male train and track maintenance workers compared with an internal male non-noise exposed reference group
| Age | Train maintenance | Track maintenance | Internal reference | p Value |
|---|---|---|---|---|
| Hearing loss compared with the internal reference, mean 3, 4 and 6 kHz, better ear (95% CI) | ||||
| −24 | 2.3 (0.8 to 3.7) | 1.1 (−0.1 to 2.3)* | 0 (Ref) | |
| 25–34 | 0.8 (−0.5 to 2.1) | 0.0 (−1.2 to 1.3) | 0 (Ref) | |
| 35–44 | 1.8 (0.3 to 3.3) | 1.1 (−0.2 to 2.4) | 0 (Ref) | |
| 45–54 | 3.3 (1.6 to 5.0) | 3.1 (1.5 to 4.6) | 0 (Ref) | |
| 55–64 | 4.6 (2.5 to 6.6) | 4.9 (2.9 to 6.8) | 0 (Ref) | |
| Coles audiometric notch, prevalence, worse ear (%) | ||||
| −24 | 50 | 56 | 39 | <0.001† |
| 25–34 | 50 | 53 | 39 | <0.001 |
| 35–44 | 59 | 62 | 50 | <0.001 |
| 45–54 | 65 | 71 | 55 | <0.001 |
| 55–64 | 60 | 66 | 52 | <0.001 |
| Total | 59 | 64 | 49 | <0.001 |
| NIHL criteria hearing loss‡, prevalence, worse ear, (%) | ||||
| −24 | 26 | 21 | 20 | 0.432§ |
| 25–34 | 36 | 29 | 28 | 0.116 |
| 35–44 | 63 | 56 | 50 | <0.001 |
| 45–54 | 87 | 85 | 74 | <0.001 |
| 55–64 | 95 | 95 | 92 | 0.005 |
| Total | 76 | 70 | 63 | <0.001 |
*Analysis of variance (ANOVA), Bonferroni post hoc.
†χ2 Test.
‡A hearing threshold of 25 dB or more at 3, 4 or 6 kHz, worse ear, or 20 dB for all of the 3, 4 and 6 kHz, worse ear.
§ANOVA.