Acceleration sound design for vehicles using distortion products

When considering the acoustic design of automobiles, generation of low-frequency sounds is advantageous as these sounds can increase users' excitement levels. However, there are several problems associated with an increase in the low-frequency levels of an engine sound. For example, it is difficult to create a balance between invoking silence and excitement in the user when a sound's different-order components are changed. It is also difficult to generate heavy-bass engine sounds in practical scenarios. Thus, the application of distortion products in the auditory system of the cochlea was considered. Distortion products are perceived when two or more sounds with slightly different frequencies are played simultaneously. This study was conducted to examine the possibility of achieving powerful engine sounds using distortion products. First, the relationship between different combinations of complex sounds and the pitch perception of distortion products was investigated. Second, the application of distortion products to acceleration sounds was considered. The results suggested the possibility of synthesizing a low-frequency component using distortion products inside the cochlea.