Adaptation properties of the acoustic reflex (AR) were evaluated in a group of normal-hearing subjects. Signals used to elicit the AR included: (1) continuous broad-band noise; (2) broad-band noise interrupted every 7.5 s. with pauses of 250, 500 and 750 ms, and (3) industrial noise. AR activity was continuously monitored for a period of 5 min. Values of acoustic admittance at the beginning and end of the test period were used to calculate percent adaptation for all five elicitor conditions. The greatest adaptation occurred during continuous broad-band-noise stimulation and the least adaptation was observed under the industrial-noise condition. The AR system appears to be resistant to the process of adaptation when activated by stimuli with periodically changing temporal signatures. Results also support previous investigations that demonstrate that the AR is extremely active in certain industrial environments.