The following aspects of the loudness of impulsive sounds were investigated on the basis of the data from a round robin test in Japan: (1) The propriety of sound exposure level as a measure for the loudness of impulsive sounds. (2) The effects of duration and decay time. (3) The relation between sound exposure level and the peak values measured by means of time constants of sound level meters. Artificial impulsive sounds were used as stimuli and their loudness was judged, using the method of constant stimuli, in 10 different laboratories in Japan. Results showed that sound exposure level has good correspondence with loudness, and that the values of sound exposure level can be approximated by peak levels measured by means of a time constant of 1 s (Slow). Duration, decay time and carrier frequency had no significant effect.