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| Chang Grade | Sensorineural Hearing Threshold (dB HL) bone conduction or air conduction with normal tympanogram |
|---|---|
|
| |
| 0 | ≤ 20 dB at 1, 2, and 4 kHz |
|
| |
| 1a | ≥ 40 dB at any freq 6 to 12 kHz |
| 1b | > 20 and < 40 dB at 4kHz |
|
| |
| 2a | ≥ 40 dB at 4 kHz and above |
| 2b | > 20 and < 40 dB at any freq below 4kHz |
|
| |
| 3 | ≥ 40 dB at 2 or 3 kHz and above |
|
| |
| 4 | ≥ 40 dB at 1 kHz and above |
