Perceptual evaluation of the sound quality of car HVAC systems

For electric and hybrid vehicles the engine sound has become a less important concern because its level is now much lower. However this reduction made other sound sources clearly audible, such as air conditioning. The CEVAS project deals with the simulation and the perception of the sounds of air conditioning (HVAC) and battery cooling (BTM) systems in cars. In the framework of the project a psychoacoustic study involving a semantic differential listening test was carried on in order to identify the perceptual space of car HVAC sounds and link it to perceived sound quality. Twelve semantic scales were presented to 20 participants in order to describe 60 HVAC sounds representative of the existing variety of systems. A principal component analysis identified a 3-dimensional perceptual space explaining more than 95% of the variance in the data. Finally regression analyses on the sound quality of the car HVAC systems revealed the expected strong influence of loudness, and more occasionally tonality and fluctuation strength.