Table 1.

Ototoxicity grading scales. Chang Scale.

Chang
Grade 0	≤20 dB at 1, 2, and 4 kHz	Normal
Grade 1a	≥40 dB at any freq 6–12 kHz	Normal
Grade 1b	>20 and <40 dB at 4 kHz	Normal
Grade 2a	≥ 40 dB at 4 kHz and above	Normal
Grade 2b	>20 and <40 dB at any freq below 4 kHz	Hearing loss
Grade 3	≥40 dB at 2 or 3 kHz and above	Hearing loss
Grade 4	≥40 dB at 1 kHz and above	Hearing loss