Direction Specific Analysis of Psychoacoustics Parameters Inside Car Cockpits: a Novel Tool for NVH and Sound Quality

Psychoacoustics parameters are widely employed in automotive field for objective evaluation of Sound Quality of vehicle cabins and their components. The standard approach relies on binaural recordings from which numerical values and curves are calculated and head-locked binaural listening playback can be performed. Recently, the Virtual Reality technology started to diffuse also in automotive field, bringing new possibilities for enhanced and immersive listening sessions. In this paper, we combine both solutions: the VR approach is adopted to calculate the principal psychoacoustics parameters. The acquisition system consists in a massive spherical microphone array featuring a camera for recording panoramic visual background. The acoustical information is encoded into High Order Ambisonics spatial format, that can be rendered on stereoscopic visors and Spatial PCM Sampling format that can be used to produce 360° colour maps. In this way, we are able to plot the psychoacoustics parameters adding their directivity information over the panoramic background, turning the array into a novel 360° diagnostic tool. At the same time, the playback can be performed inside Ambisonics listening rooms or binaurally reproduced over HMDs, benefiting from head-tracking and also personalized HRTFs. Two case studies are presented: a laboratory experiment and an in-car measurement. In the first, a source produces a sharp annoying sound inside a noisy room. The mapping technique is used to localize the source based on psychoacoustic parameters, whilst the standard SPL map does not work. In the second, a wideband RNC system has been measured to evaluate its spatial SQ performances. A novel diagnostic tool has been shown: it displays the spatial information of the principal psychoacoustics parameters making it possible to localize the most annoying sources. In addition, it allows a jury test to make subjective evaluations, performing listening tests with binaural head tracking and personalized HRTFs.