Identification of Sound Quality Parameters With Respect to Subjective Feel of HVAC Noise of Diesel SUV’s

Recent trends in developing quieter diesel power plants in automobiles leading to unmasking the secondary sound sources. One of the major secondary sound sources of in-cabin noise is HVAC system. HVAC noise is one such sound likely to be present as long as the automobile is in use. In extreme climatic conditions, like in India, HVAC is majorly operated at higher speeds and adding to that SUV volume requires more air circulation which generates lot of flow induced noise. Under these conditions, the contribution of HVAC noise is more significant for passengers and many a times it influences subjective cognition that causes the driver’s emotional response to be unpleasant, it is more important to identify the most significant sound quality parameters that contribute to the perception of HVAC noise. Measurements were done on five different diesel SUVs with different HVAC operating conditions each having variable fan speeds with engine on and off respectively. Using the semantic differential technique subjective rating of the measured signals has been done. The psycho acoustic parameters calculated objectively for the measured interior sounds later those were compared with subjective rating by using HVAC noise function (HNF) to obtain the suitable parameters to represent HVAC noise.