Psychoacoustical Characteristics of Impact Ball Sounds on Concrete Floors

Abstract

Measurements of impact sounds generated by an impact ball (heavy/soft impact source) were conducted in apartment buildings with box-frame type reinforced concrete structures. Variations in frequency characteristics were found in the impact ball sounds and these were classified into three frequency groups. An auditory experiment was carried out to investigate the relationship between various level indices and subjective responses to floor impact sounds. It was found that sound quality ratings (LLz and N-max) as well as instrumental metrics (L-Aeq, L-Amax and L-m,L-1/1(63-500)) showed good correlation with impact sound annoyance. Among them, LAmax was suggested as a practical descriptor of the auditory sensation of impact ball sounds on the basis of measurement and calculation procedures. Additional auditory experiments were conducted to characterize the classified impact sound groups and to evaluate the annoyance of impact ball sounds through paired comparison and semantic differential tests. The results show that the impact ball sound with a dominant sound pressure level at 250 Hz was most annoying. Sound Quality (SQ) metrics were used to explain the annoyance level of heavy-weight floor impact sounds. The annoyance obtained from the paired comparison test correlated well with loudness and fluctuation strength. In the semantic differential test, it was found that the adjectives describing loudness had a dominant effect on the subjects' annoyance levels.