Study on sound quality control of engine noise and its evaluation

The conventional solutions to reduce car-engine noise are subject to considerable structural variations. Low frequency sound often cannot be reduced employing ordinary passive methods; only the active control of noise provides a universal solution. On the other hand, the traditional production concept for car engine sound has changed from finding a solution to unwanted noise, to design a particular sound. Although many studies have investigated the development of comfortable car-engine sounds, the psychoacoustic effects of time-varying rate for accelerating engine sounds remain unclear. If the loudness is applied to the engine acceleration sound that is non-stationary, it might be interpreted incorrectly. Therefore, we proposed new indicator for non-stationary noise. We have applied new indicator to car acceleration sound. In order to find the desired sound as the engine sound, we investigated the relationship between the harmonic structure and the auditory impression of the engine sound. Further, to change to the desired car-engine sound, we tried to apply the Command Fx-LMS algorithm to actual car-interior noise.