Table 1
Characteristics of the study participants and their relationship with Temporal threshold shift (TTS) among iron and steel workers.
| DESCRIPTIVE VARIABLE | TEMPORAL THRESHOLD SHIFT, DEFINED AS HEARING THRESHOLD SHIFTS DB >10 DB AT 1000, 2000, 3000 OR 4000 HZ | ||
|---|---|---|---|
| YES | NO | ||
| (N, %) | (N, %) | ||
| Personal noise exposure, LAeq,8h | |||
| 85.0–89.0 | 32 (29.1) | 29 (90.6) | 3 (9.4) |
| 89.1–92.4 | 52 (47.3) | 45 (86.5) | 7 (13.5) |
| 92.5–95.5 | 26 (23.6) | 20 (76.9) | 6 (23.1) |
| All | 110 (100.0) | 94 (85.5) | 16 (14.5) |
| Age-group (years) | |||
| 20–27 | 41 (37.3) | 35 (85.4) | 6 (14.6) |
| 28–35 | 34 (30.9) | 31 (91.2) | 3 (8.8) |
| 36–47 | 35 (31.8) | 28 (80.0) | 7 (20.0) |
| Duration of work (years) | |||
| 0–3.0 | 41 (37.3) | 33 (80.5) | 8 (19.5) |
| 3.1–7.0 | 35 (31.8) | 32 (91.4) | 3 (8.6) |
| 7.1–20 | 34 (30.9) | 29 (85.3) | 5 (14.7) |
| Current smoking | |||
| No | 96 (87.3) | 82 (85.4) | 14 (14.6) |
| Yes | 14 (12.7) | 12 (85.7) | 2 (14.3) |
| Use of earphones/headphones | |||
| No | 96 (87.3) | 81 (84.4) | 15 (15.6) |
| Yes | 14 (12.7) | 13 (92.9) | 1 (7.1) |
| MEAN (SD) | MEAN (SD) | MEAN (SD) | |
| Personal noise exposure, dB(A) | 90.4 (2.7) | 90.2 (2.6) | 91.1 (2.6) |
| Number of noise peaks >130, dB(C) | 12 (9.7) | 10 (9) | 16 (12) |
Figure 1
The mean hearing thresholds (dB) at pre- (open boxes) and post- (dotted boxes) shift audiometries with respective standard deviations for 1000, 2000, 3000 and 4000 Hz (N = 55). The difference between the pre- and post-shift hearing thresholds was statistically significant for all frequencies (paired samples t-test, p < 0.001).
Figure 2
Pre-shift hearing threshold (solid lines) and post-shift hearing threshold (dotted lines) for the frequencies 1000, 2000, 3000 and 4000 Hz among noise-exposed workers (N = 55).