Eight male subjects were exposed for 3 min to a 4000‐cps fatigue tone at 40 dB SL. Each subject was tested under four task conditions: mental arithmetic (MA), written long division (LD), threshold determination (TD) on a 500‐cps tone, and reverie (REV). Temporary threshold shifts (TTS) were computed by comparing pre‐ and post‐fatigue thresholds. MA produced significantly more TTS than any other condition and LD resulted in greater shifts than REV. Amount of auditory fatigue can vary with the type of mental activity performed by the subject.