To show the effect of the temporal pattern of acoustic stimulation on TTS15 min, guinea pigs were subjected to isoenergetic noises with the same spectrum. The exposures in a first experimental series were continuous noises and noise bursts. The continuous noise was presented with different durations and levels but always with the same energy. The noise burst stimulation consisted of a constant number of bursts with different interstimulus intervals. Both duration and repetition rate were shown to affect the TTS15 minmeasured for these isoenergetic stimuli. A duration of 225 to 1800 s and a repetition rate of one per second produced the greatest TTS15 min. In a second experimental series continuous noise and acoustic impulses with the same spectrum and 100‐Hz repetition rate were presented at different levels. In this case the waveform of the stimulus (phase spectrum) was shown to have an effect on TTS15 min.