TABLE 1.
Comparison of incidence rates for STS between the two groups
| Study group (N = 119) | Control group (N = 105) | |
|---|---|---|
| Age; years (mean ± SD) | 22.31 ± 1.44 | 22.36 ± 1.40 |
| Number of ears | 238 | 210 |
| Pre‐noise exposure | ||
| Normal hearing thresholds | 234 (98.3%) | 200 (95.2%) |
| Post‐noise exposure | ||
| STS | 153 (65.4%) | 150 (75.0%) |
| Positive STS (increase in hearing threshold) | 48 (31.4%) | 83 (55.3%) |
| Right ears | 23 (47.9%) | 43 (51.8%) |
| Left ears | 25 (52.1%) | 40 (48.2%) |
| Negative STS (improvement in hearing threshold) | 105 (68.6%) | 67 (44.7%) |
| Right ears | 55 (52.4%) | 30 (44.8%) |
| Left ears | 50 (40.6%) | 37 (55.2%) |
| Early warning sign of permanent hearing loss | 8 (5.2%) | 8 (5.3%) |
| Right ears | 5 (62.5%) | 5 (62.5%) |
| Left ears | 3 (37.5%) | 3 (37.5%) |
Note: STS—either a 10 dB INCREASE or DECREASE in hearing threshold averaged across 2, 3, and 4 kHz in the same ear from an individual's baseline, confirmed by a retest, and shifting to a pure‐tone average threshold that exceeds 25 dB HL. Positive STS—an increase (worsening) of 10 dB or greater for the average of 2, 3, and 4 kHz in either ear. Negative STS—a decrease (improvement) of 10 dB or greater for the average of 2, 3, and 4 kHz in either ear. Early warning sign of permanent hearing loss – a post‐noise exposure threshold shift at a single frequency of 15 dB at 1, 2, 3, or 4 kHz and that results in a hearing loss as defined as a threshold in excess of 25 dB HL.
Abbreviation: STS, significant threshold shift.