Noise cancelation technology is something that's more than just for high-end travel headphones. Now even smartphones use a dual microphone setup to help improve sound quality, and believe it or not, GM putting noise cancelation into its new trucks.
Aside from trying to minimize cabin noise, the engineers had another reason to introduce noise cancelation, and that all started with the quest for better fuel economy.
When GM engineers set out to deliver better fuel economy on the GMC Terrain, they chose to lower the 6-speed transmission's gear shift points to enable the Ecotec 2.4L four-cylinder engine to run at lower rpm torque. In this "Eco" mode, which the driver can activate with a click of a button on the console, the torque converter clutch engages at lower engine speeds to help save gas. While the engineering action improved fuel efficiency by up to one mpg, it also created an objectionable low-end frequency boom. To counteract that boom the engineers turned to active noise cancellation technology.
Terrain's noise cancellation system relies on two microphones embedded in the headliner to detect the hum and prompt an onboard frequency generator to create counteracting sound waves through the audio system's speakers and sub-woofer. The system also reduces higher rpm engine noise at highway cruising speeds to help keep the vehicle interior quiet.
"Terrain measured quieter than the Honda CR-V and Toyota RAV4 in our on-road interior noise tests," said Jim Vallance, noise, vibration and harshness development engineer. "At 70 miles per hour, Terrain's interior is quiet enough to allow conversation in normal tones of voice."