Prevention of blindness and deafness

Grades of hearing impairment


Grade of impairment Corresponding audiometric ISO value Performance Recommendations
0 - No impairment 25 dB or better
(better ear)
No or very slight hearing problems. Able to hear whispers.  
1 - Slight impairment 26-40 dB
(better ear)
Able to hear and repeat words spoken in normal voice at 1 metre. Counselling. Hearing aids may be needed.
2 - Moderate impairment 41-60 dB
(better ear)
Able to hear and repeat words spoken in raised voice at 1 metre. Hearing aids usually recommended.
3 - Severe impairment 61-80 dB
(better ear)
Able to hear some words when shouted into better ear. Hearing aids needed. If no hearing aids available, lip-reading and signing should be taught.
4 - Profound impairment including deafness 81 dB or greater
(better ear)
Unable to hear and understand even a shouted voice. Hearing aids may help understanding words. Additional rehabilitation needed. Lip-reading and sometimes signing essential.

Grades 2, 3 and 4 are classified as disabling hearing impairment.

The audiometric ISO values are averages of values at 500, 1000, 2000, 4000 Hz.

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