Reducing car audio button noise while maintaining tactile quality

Recently, interior noise levels of passenger cars have been significantly reduced. The reduction of major cabin noise led to the recognition of small noises that are previously unnoticed. Specifically, the button noises of electrical devices in passenger compartments have been identified as belonging to this category of noise. The aim of this study is to improve the auditory quality of a car audio button while maintaining its tactile quality that is familiar to users. The tactile and auditory qualities can be described by the load versus stroke characteristics and the operation noise level. For buttons with rubber domes, the buckling behavior of the domes governs the tactile and auditory qualities. To preserve the tactile quality, the sensitivity of load versus stroke characteristics to each of the eight identified parameters is obtained from the finite element analyses using model parameters varied by ±10%. Four parameters to which the tactile quality was insensitive are selected. To identify the contributions of these four design parameters to auditory quality, finite element analyses were performed in conjunction with design of experiments. The improved design obtained by the subsequent response surface methodology optimization was validated by a prototype test with a 12 dBA reduction in noise.