Noise-Induced Hearing Loss and Presbyacusis

Abstract

The effect of aging on hearing (threshold) levels at 1 000 and 4 000 Hz was investigated in war veterans who had normal hearing for their age at 1 000 Hz and considerable hearing losses at 4 000 Hz (produced by acoustic trauma or other war-time noise exposure) when first tested audiometrically. It was found that the threshold levels at both 1 000 and 4 000 Hz had increased by approximately the amounts predicted by presbyacusis curves, in spite of the hearing losses at 4 000 Hz. The results thus support the hypothesis that presbyacusis and noise-induced hearing loss are independent and additive at 4 000 Hz.

Key Words:

• Male war veterans
• War-time noise exposure
• Acoustic trauma
• Presbyacusis equations