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. Author manuscript; available in PMC: 2015 Apr 1.
Published in final edited form as: Pediatr Blood Cancer. 2013 Nov 1;61(4):601–605. doi: 10.1002/pbc.24830

Table I.

Ototoxicity Grading Scales*

Chang SIOP
Grade 0 ≤ 20 dB at 1, 2, and 4 kHz Grade 0 ≤20 dB HL at all frequencies
Grade 1a
Grade 1b		 ≥ 40 dB at any freq 6 to 12 kHz
> 20 and < 40 dB at 4kHz		 Grade 1 >20 dB HL (i.e. 25 dB HL or greater) SNHL above 4000 Hz (i.e. 6 or 8 kHz)
Grade 2a
Grade 2b		 ≥ 40 dB at 4 kHz and above
> 20 and < 40 dB at any freq below 4kHz		 Grade 2 >20 dB HL SNHL at 4000 Hz and above
Grade 3 ≥ 40 dB at 2 or 3 kHz & above Grade 3 >20 dB HL SNHL at 2000 Hz or 3000 Hz and above
Grade 4 ≥ 40 dB at 1 kHz and above Grade 4 >40 dB HL (i.e. 45 dB HL or more) SNHL at 2000 Hz and above
*

Sensorineural Hearing Threshold (dB HL) bone conduction or air conduction with normal tympanogram