The protective effect of the acoustic reflex for impulsive noises.

Twenty‐four male subjects were trained in the use of the Bekesy audiometer. Then they were exposed to 100 rounds of machine‐gun fire, both with and without a pre‐exposure to a 1000‐cps tone for activating the acoustic reflex. Pre‐ and post‐firing audiograms, taken under both conditions, were compared to determine temporary threshold shifts. Shifts obtained with the reflex‐activating tone were found to be significantly smaller than those obtained in its absence.