On nearly every street and highway in the world, digital signal processing (DSP) is improving the sound from someone’s car stereo. But as more communications functions are added to cars, and more functions become automated, DSP is finding uses far beyond traditional audio. These new applications help make cars more comfortable, more reliable, and safer.
The microphone positioned above the driver’s head has become a common sight in cars. Most are used only for phone calls, but the addition of more microphones plus DSP can improve phone calls and voice recognition, and add new functions. Using an array of small microphones instead of just one allows beamforming, so array’s pickup pattern can automatically be “steered” toward the speaker. This arrangement helps reject road/engine noise and make voices sound clearer. Adding microphones at more points in the cabin facilitates automatic road/engine noise cancellation, where the DSP picks up the interior noise and uses the car’s stereo system to create a reverse sound wave to cancel the noise, so the driver and passengers enjoy a quieter environment.
New engines designed for maximum fuel efficiency or employing hybrid power rarely sound the way we expect a well-tuned engine to sound, and new lightweight door and trunk lid materials may not deliver the reassuring “thunk” we expect. DSP can work in conjunction with a car stereo system to synthesize operating sounds, so any car can deliver the kind of gratifying user experience we expect, especially in a luxury sedan.
DSP used in conjunction with microphones can also monitor the operation of a car and the environment around it. Microphones placed around key components and filtered using DSP can detect engine and drive train malfunctions. Microphones placed on the car’s exterior, again filtered with DSP, can pick out the sounds of emergency vehicles or even impacts to warn the driver or activate automatic safety systems.
DSP Concepts’ Audio Weaver makes it easy to program and optimize a DSP for such varied tasks. Its modular, drag-and-drop graphical interface lets system designers choose from more than 250 processing modules, with familiar onscreen knob and slider controls for easy adjustment. Audio Weaver is compatible with many of the new system-on-chip (SoC) components that form the core of most new cars’ electronic systems.