The loudness of repeated impact sound (A study on the loudness of impact sound. IV)

The effect of repetition of impact sound on its loudness is investigated. The stimuli used in this experiment are the repeated model impact sounds which have triangular envelope after the actual impact sounds, and they are synthesized by amplitude modulation of sinusoidal carrier. The stimulus is repeated 1, 2, 4, or 8 times with the interval of 100, 200, or 400 ms. As the results of this experiment, PSE for loudness of repeated impact sound increases by about 1 dB for doubling of the number of repetition, and it shows a tendency of saturation along with the increase in the number of repetition. PSE for loudness corresponds to a lesser degree to the energy principle, since doubling of the number of repetition means 3 dB increase of sound energy. The readings of SPL, measured by a sound level meter with a square circuit of 125 ms rise time constant and 200 ~ 300 ms decay time constant, may well describe the loudness of repeated impact sound.