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As an avid sport fisherman, General Motors development engineer Frank Delekta enjoys the peace, quiet and tranquility of Michigan lakes and streams. His sense for silence – and the use of advanced technology – served him and his team well in their mission to bring luxury-like interior quietness to the 2013 Chevrolet Cruze.
The engineering team used a number of noise-reducing and noise-cancelling technologies on the Cruze body structure, including 30 distinct acoustical treatments. For example, the acoustic package on the Cruze is a Liquid Applied Sound Deadener applied strategically throughout the body structure and melted into place when the body passes through the paint oven.
The doors have triple seals and feature fiberglass “blankets” that serve as water, airflow and noise barriers. They close with a solid, precise sound and no resonance . Before devising these solutions and many more, engineers performed intensive testing throughout the vehicle’s development.
Delekta and his colleagues have significantly sharpened their hearing skills because of their years of experience working in GM’s Squeak and Rattle Lab at the Milford (Mich.) Proving Ground.
“I have a pretty acute sense of hearing,” said Delekta. “Outside of work, if I ask someone ‘Did you hear that?’ the answer is almost always ‘No.’ I hear noises that others don’t.”
Delekta’s team leveraged Chevrolet’s design and engineering talent in North America, Asia and Europe, all regions where the Cruze is sold. Engineers reported on noises they heard while driving across a variety of real-world roads at various speeds. The team replicated those conditions in the lab to find the source of the noise. Among the tools was a state-of-the art environmental four-post simulator that mimics the world’s most-challenging road surfaces.
This intense testing allowed engineers to adjust for interior compartment noise early in the vehicle development process.
And the team didn’t just beat up the Cruze at room temperature. Test vehicles were put into a climatic anechoic chamber to evaluate the sounds that can emerge at extreme temperatures – from minus 20 to 120 degrees Fahrenheit in the same day.
“A component may squeak or rattle at 100 degrees but not below freezing or vice versa,” said Delekta. The brutal road and lab testing led to improvements in 74 components resulting in a quieter ride.
One of these was traced to the audio system itself. A nasty rattle from the rear deck lid was traced to bigger speakers capable of pumping out more volume for decibel-hungry North Americans. Engineers used an attachment clip to stabilize the panel that houses the rear deck lid speakers, eliminating the sound. The clip also allows for better audio fidelity through Cruze’s optional Pioneer premium speaker system.