Continuous judgment of sound quality of electric home appliances

The sound quality of machinery noises is multi-dimensional and is often examined using semantic differential. In this case the overall impression of sound quality is judged. However, sound quality may vary according to the temporal stream of sounds. In this study, sound quality of electric home appliances was judged using the continuous judgment by line length. Forty-one kinds of the sound of home electric appliances were connected in random sequences with a slight interval between the sounds. The original sounds and their modified sounds were included in the stimulus of 8 min. The experiment was conducted in Technische Universiät München. Ten German participants joined the experiment. They conducted three sessions in which they judged the instantaneous impression of loudness, sharpness and unpleasantness, respectively. The subjective responses were sampled every 100ms. The values of every 100ms of LAeq, LLz(p), calculated sharpness and comfort index (CI) were measured. As a whole the physical metrics showed good correlation with subjective judgments. On the other hand, when the relation between physical metrics and subjective judgments was examined in a limited portion, different tendency was found. It would be better to examine the sound quality along the temporal stream in detail in order to find the clues to improve the sound quality.