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Two heads were better than one when Buick engineers were working on the new Lucerne.

As the flagship of the Buick line, it serves as a showcase for the advances the company has made in acoustic and analytic analysis. The goal was simple: Set new industry standards.

We're not talking about installing a new audio system and locating and sizing the speakers for maximum effectiveness and accuracy. We're talking about working with the vehicle itself and its components to ensure the sounds the occupants can hear are not only minimal but pleasant.

The goal is to block, reduce, absorb or alter sounds ranging from road and wind noise to how a door sounds, from inside and out, when it is being closed.

Blocking and reducing noise is done through things like seals and laminated glass and steel. Absorbing sound falls to various -- and strategically located -- materials like special foams and blankets.

Altering sound is a much more complicated process involving filters and other tricks.

During the development stages of a new vehicle, a lot of attention goes into identifying and dealing with sounds.

Obviously accurate measurement and reproduction of the sound is the key.

Throughout the development of the Lucerne the engineers used a device known as "Aachen HEAD" to measure the interior noise levels while the vehicle was in motion.

This incredibly sophisticated digital recording device, named after a university in Germany where it was developed, allows engineers to simulate the way humans process sound.

Shaped like a human head, it contains specially-calibrated and highly accurate digital microphones within each ear position connected to a 24-bit recording unit.

The typical acoustic memory of the human ear --the ability to judge subtle differences in sound levels and quality -- lasts only 10 seconds.

Making changes to a component or jumping from vehicle to vehicle takes more than that, so accurate comparisons are difficult and often flawed.

The Aachen HEAD allows the acoustic engineers to record sounds as the human ears hear them and replay them over and over again.

During the Lucerne development process, these units were placed in various seating locations and sound levels sampled at various speeds over a variety of road and ambient conditions. They measured everything from the air conditioning unit to the door handles and tires.

After the sounds had been recorded, as many as 24 engineers gathered in GM's acoustically-tuned "Jury Room" to listen to and evaluate multiple recordings back-to-back and make decisions in one to two hours, significantly reducing development time.

Lead acoustical engineer George Bei says it is one thing to reach numerical acoustic targets and quite another to ensure the quality of those sounds is pleasant. His team measured and tuned everything from the power train and body structure to the sound emitted when the glove box door is closed.

"By using the Aachen HEADs, we were able to subjectively identify and play back various sounds using digital filters at critical frequency ranges, which allowed us to craft an overall sound quality that harmonizes with the Lucerne's interior character we were striving for," Bei says.

The Aachen HEAD is used throughout the industry. As another example of its use, Ford engineers used it to evaluate and alter the Quiet Steel in the Sport Trac while satisfying the structural needs of the vehicle. The Aachen HEAD allowed them to remove additional material and simplify the entire vehicle assembly process.

Noise, vibration and harshness are the bane of vehicle development. Increasingly sophisticated measurement devices like the Aachen HEAD mean we can look for improved results in this area.

globeauto@globeandmail.com