Design and implementation of comfort-quality HVAC sound inside a vehicle cabin

Abstract

This study presents a practical heating, ventilation, and air-conditioning (HVAC) system that emits good-quality sound along with a pleasant and cool climate inside a vehicle cabin. This development included two steps. The first step was to design a new HVAC sound while the second step focused on the development of an active electric control system (AECS) inside cars; the AECS is used to emit a HVAC sound inside the vehicle cabin. To design the new HVAC sound with a pleasant and cool feel, a sound-quality index is necessary to evaluate which sound is pleasant. Therefore, two indices was developed based on subjective tests and the psychoacoustic parameters of HVAC sounds of 7 luxury passenger cars. A new HVAC sound was designed by adjusting the magnitude and phase of the HVAC sound recorded inside a test car. After designing the new HVAC sound, to deploy it at the driver seat of the test car, the AECS was employed. The source signal of the AECS was obtained using an inverse filter, which was designed based on the least-square method. The source signal was used as the input signal of the car audio part of the AECS. The output sound of the AECS was added to the existing HVAC sound to achieve a new HVAC sound at the driver seat. The sound quality of the new HVAC system was evaluated using the two developed indices.