Active Noise Control (ANC) and Active Sound Control (ASC)
Key contributors to Insight's quiet, refined interior are Active Noise Control (ANC) and Active Sound Control (ASC). The two systems are comprised of dual overhead microphones, an ANC/ASC electronic processor, and the audio system's speakers. ASC/ANC operates whenever Insight is running, even if the audio system is turned off.
ANC is designed to reduce low frequency sound in the cabin caused mainly by the roughness of the road surface. The overhead microphones pick up sound waves and send them to the ANC/ASC processor, which then creates and sends a precisely timed "reverse phase" audio signal to a special amplifier. In turn, the amplifier drives the speakers to cancel the original noise signal.
ASC is a related technology designed to improve the engine sound quality by making the sound pressure level more linear as the engine revs increase. Typically, engine noise doesn't increase in a linear way with rising revs; instead there can be many resonances that create peaks and valleys in the sound pressure level and an uneven sound. From idle to redline, ASC helps smooth out the engine sound by reforming the sound signal as needed and sending it to the speakers. In SPORT mode, ASC provides Insight with a more dynamic engine sound profile.