Two subjective assessments were performed focusing on the auditory impression of automotive HVAC noise concerning coolness and warmness. First, paired comparison tests were carried out under various conditions of room temperature. Five stimuli were synthesized by stretching the spectral envelopes of recorded automotive HVAC noise to assess the effect of the spectral centroid. Twelve normal-hearing subjects were asked to rate the auditory impression of the stimuli for each pair on a seven-point

more »

... cale according to how much the latter is warmer (for the winter tests) or cooler (for the summer tests) than the former. Results show that the spectral centroid significantly affects the auditory impression concerning coolness and warmness; a higher spectral centroid induces a cooler auditory impression regardless of the room temperature. Second, effects of HVAC noises on the subjects' sensation of coolness and warmness were evaluated by using a method of continuous judgment by category. Room temperature were controlled to increase/decrease linearly, and HVAC noise, having warm/cool auditory impressions, were presented. Subjects had to answer their sensation of coolness/warmness at regular time intervals. The results showed that HVAC noise had significant effect on the time change rate of sensation of coolness/warmness.