The four-cylinder powertrain operate at the fuel-conserving range of 1,000 to 1,500 RPM. Noise reduction is attained through acoustically laminated windshield and front-door glass. Liquid-applied sound deadener applied to the floor pan and trunk help. The car uses triple-sealed doors with acoustic perimeter water deflectors, sound-absorbing carpets and dash mat. There’s also acoustic foam baffles inside body cavities and between inner and outer quarter panels, and an isolated engine cradle.
The mobile studio Impala’s interior acoustics were tested with a mannequin-like binaural recording device, Aachen Head with specially calibrated microphones to record a dynamic range equal with human hearing during test drives on a range of road surfaces at GM’s Milford Proving Ground.
“The Corktown wobble, the Motor City slide, some Detroit throttle with that good time vibe, we’ll get in the Impala and take that ride, ‘til we feel like we’re 25 miles above the sky,” Frankie sang while Mark Pastoria of Harmonie Park Studios recorded it onto a laptop computer.
“I am amazed at how quiet the Impala is,” Pastoria said, after playing the vocal recording through Impala’s audio system. “It was important that we wouldn’t hear background noise while recording, and with all that was going on outside the car, I am astounded that we couldn’t hear any of it. The Impala rocks.”
“Achieving a high level of acoustic refinement requires the most advanced tools available and many hours of road testing,” said GM noise and vibration engineering specialist, Stephanie Ernster. “The new Impala benefitted from both, resulting in a quiet driving experience that is truly something to sing about.”
“Having a quiet cabin makes it easier for Impala’s voice recognition software to understand commands,” said Kara Gordon, a General Motors’ noise and vibration performance engineer. “A quieter cabin also makes it easier for front and backseat passengers to have a conversation at normal speaking levels.”