Dynamic Sound Control Algorithms in Automobiles

Automobiles comprise acoustical environments far from being considered desirable. Therefore, it is necessary that acousticians conduct a vehicle dependent tuning, in which they try to counteract the deficiencies of the room, the loudspeakers, the way the loudspeakers are embedded in the interior and so on. This is achieved by manipulating the channel dependent phase and magnitude responses. As result they are able to enhance the acoustic quality of the system, providing a more enjoyable sound experience. The whole tuning is done while the car is standing still and the engine is turned off.

Usually passengers listen to any kind of sound source whilst driving. Therefore, they inevitably face background noise of any coloration or intensity. It is the task of a dynamic sound control algorithm to compensate for the dynamic changes of the background noise in order to keep the sound impression like it was after the tuning, which was done without any disturbing background noise.

In this chapter we will give an overview of different dynamic sound control systems. Starting with systems controlling just the volume by utilizing nonacoustical and/or acoustical sensor signals, we will turn to more advanced systems whose task it is to control the whole spectrum. This can be considered as a dynamic equalization control.

Finally, we will describe a spectrum-based dynamic equalization control algorithm, applying a psychoacoustic masking model, in more detail, discussing theoretical as well as practical aspects. The chapter will close with the summary of the discussed approaches and by providing a look in the future of forthcoming systems.