Abstract
The loudness of impact sound which has a steady part is compared in this paper with one having no steady part. PSE for loudness of impact sound with steady part longer than ten odd ms corresponds well to its sound energy level, while it shows a rather higher level for the steady duration of about 10ms or less. This difference is explained by the spread of frequency spectrum for the shorter duration. A method to compensate for this deflection of PSE from energy rule is to apply the weighting function of 6-8dB/oct to components beyond the critical band around carrier frequency. PSE for loudness of impact sound corresponds to the peak sound energy level observed through a time window of the form “exp (-βt)”, where β is the damping constant of 5-10. This value of β is equivalent to the time constant of 100-200ms in a square circuit of a sound level meter. And the mean value of readings of SPL measured by the sound level meter with 5ms time constant and the one measured by the meter with 125ms time constant may well describe the loudness of impact sound even when its duration is very short.
