Three experiments compared the amounts of temporary threshold elevation resulting when a given total amount of noise energy was presented to the ear in the form of repeated, short, intense bursts, and in the form of continuous noise (of much lower maximum intensity). Several patterns of noise bursts were tested, as well as continuous noise. One‐millisecond noise bursts and continuous noise, of 20 min duration, were tested most extensively. The most severe impulsive noise tested consisted of 1‐msec bursts every 10 msec for 20 min, with a burst SPL of 127 db or long‐time‐average level of 117 db.
It appeared quite conclusively that 1‐msec bursts of noise have considerably less effect than the equivalent amount of continuous energy on thresholds at 3000, 4000, 6000, and 8000 cps. Noise bursts of 10 msec, 100 msec, and 1 sec length were tested less extensively; it appears that they would cause no more threshold elevation than would the equivalent amount of continuous noise.