Psychoacoustic assessment of auditory impression of the coolness and warmness induced by HVAC noise

Abstract

Noise induced by a heating, ventilation and air conditioning (HVAC) system in a vehicle is an important factor that affects the comfort of the interior of a car cabin. To date, much effort has been devoted to reduce noise levels. However, for example, silence sometimes causes a loss of operation feeling—we recognize the HVAC doesn't work enough in case the air flow sound is too quiet, even if it works well actually. Therefore, there is a need for a new sound design that addresses the noise problem from a different point of view in addition to the reduction of noise levels. In this study, focusing on the auditory impression of automotive HVAC noise concerning coolness and warmness, listening tests were performed using a paired comparison technique 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, and were presented through headphones at 70 dBA. 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.