Average hearing at 500, 1000, 2000 Hz is 45 db in the left ear. Percentage hearing loss in left ear is, when 25 dB loss is considered normal:
Ref: Diseases of Ear, Nose and Throat, By Mohan Bonsai Page 164 Explanation: DEGREE OF HEARING HANDICAP The hearing impairment can affect person's ability to hear and perform certain activities (disability). The degree of hearing impairment and handicap are termed in percentage for purposes of compensation. METHOD OF CALCULATING IN PERCENTAGE Calculate the average of thresholds of hearing for speech frequencies of 500, 1000 and 2000 Hz for the ear (say A). Deduct from it 25 dB (as up to 25 dB loss is considered normal) means A-25. Multiply it by 1.5 means (A-25) x 1.5. This the percentage of hearing impairment for the ear. Percentage handicap of an individual = 1 6. Example of calculating hearing impairment in each ear and total hearing handicap 500 Hz 1000 Hz 2000 Hz Average Right ear 50 65 80 65 dB Left ear 20 35 50 35 dB Right ear impairment % (65 - 25) x 1.5 = 60% Left ear impairment % (35 - 25) x 1.5= 15% Total handicap / 6 = 22.5 = 23% * In the given case, the ear impairment percentage is calculated as: (45-25) x 1.5 = 20 x 1.5 = 30% = 0.30
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