Influence of alcohol on the acoustic reflex and temporary threshold shift.

Blood alcohol levels between 0.09% and 0.15% were found to reduce the protective action of the acoustic reflex in five human subjects with normal hearing. Specifically, acoustic reflex thresholds were raised, reflex magnitude decreased, and temporary threshold shift increased under alcohol conditions. Stimuli consisted of a narrowband noise (500 to 1,000 Hz) and a 500-Hz pure tone. Measurements were made at blood alcohol concentrations from 0.05% to 0.15%. Temporary threshold shift at 1,000 Hz was determined three minutes after a ten minute exposure of narrowband noise at -5, +5, and +20 dB relative to the subject's prealcohol acoustic reflex threshold.