Adjustment of soft sounds in cars for multisensory harmony

Advances in vehicle sound optimization and use of innovative powertrain concepts change the vehicle interior towards a notably quiet environment. In combination with increased autonomous vehicle functionality, this enables enhanced driving comfort and extended usability. The vehicle interior has the potential to provide the ambience of a living room. Nonetheless, the quiet car will still feature a variety of sounds. Auditory feedback of the various functions is still needed. Switch sounds and sounds generated by touching surfaces during haptic activity will be more clearly audible. Furthermore, sounds excited by body movement when clothes are rubbing over seat surfaces gain attention. All sounds need careful adjustment to provide plausible feedback, ensure a comfortable ambience, and contribute to a maximum multisensory harmony. This contribution addresses concepts of sound design within a quiet vehicle interior. Particularly, adjustment of the perceived intensity of auditory signals is required to assign sounds to foreground functions which need immediately attention, or to merge soft sound into a background of less importance. How can material touch sounds be optimized? How can sound properties be adapted to the multisensory appearance of the vehicle interior? How can soft sounds contribute to an ambience which is both quiet and lively? Keywords: Psycho-acoustics, Touch sounds, Electric vehicles, Sound design, Multisensory Harmony