Left-right asymmetry in the human response to experimental noise exposure. I. Interaural correlation of the temporary threshold shift at 4 kHz frequency.

Most epidemiological surveys concerning populations exposed to occupational noise or random populations have shown that the left ear is slightly but significantly poorer than the right ear, especially at frequencies most susceptible to noise damage. To experimentally study the possible left-right asymmetry in response to noise exposure, 28 non-shooting healthy young adults were exposed binaurally to symmetrical broad-band noise for a maximum of 8 h. 4 kHz hearing thresholds of each individual were monitored alternately in the left and right ears during short interruptions in the exposure. Considerable efforts were made to exclude any external factors that might influence the left-right asymmetry. A significant positive correlation between the temporary threshold shifts (TTS) in the left and in the right ear was found. The average TTS was higher in the left than in the right ear, the difference between ears being statistically indicative.