Annex 2.
Descriptive table of Brock et al.'s proposed classification (1991)
| Hearing loss Bilateral | Grade |
|---|---|
| < 40dB at all frequencies | 0 |
| ≥ 40 dB only at 8.000Hz | 1 |
| ≥ 40 dB starting at 4.000Hz | 2 |
| ≥ 40 dB starting at 2.000Hz | 3 |
| ≥ 40 dB starting at 1.000Hz | 4 |
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