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New Arctic lab can tailor engine sound

August 18, 2003
Filed under Features

If Arctic Cat celebrated the opening of its new Noise, Vibration and Harshness lab with a raucous party, engineers would be able to monitor the sound, pinpoint the biggest noise-makers and usher them out of the room.
That’s what Bala Holalkere, engineering design manager for noise, vibration and harshness (NVH) and his team of five are attempting to do for snowmobiles.
“Arctic Cat is very much committed to meeting the regulatory requirements (for decibel levels) but we also want to make sleds distinctly different from our competition with smoothness and sound,” Holalkere said.
With this facility, Holalkere and his team plan not only to lessen the noise output of snowmobiles, but improve the sound quality, create a special tone for the machines and eliminate vibration. Their work should start appearing on the 2005 model year lineup, he said, though changes will be subtle at first.
“Up until this moment, we’ve just been covering up noise,” he said. The emphasis now will be to isolate noise and alter it, he added.
In the facility, Holalkere defines “noise” as the negative version of “sound.” Vibration, he said, is the tactile feeling that is felt through the body has contact with the snowmobile: the handlebars, the foot rests and the seat.
So far, the team has identified and prioritized target areas of sound and vibration, including the track, intake, exhaust and engine.
“We’ve set a target for the whole vehicle,” Holalkere said, “and then we’re taking a look at the individual components.” The engine, which people tend to consider the biggest noise-maker, really isn’t, he added.
For dealers, benefits may come by using the machine’s sound as a selling point. Customers, Holalkere said, should be able to hear and feel a difference in the snowmobiles.
Sound Studio
The new NVH facility, which constitutes a “large investment” according to Arctic Cat spokesman Jay Lusignan, takes up 3,500 square feet of space and is located across from the company’s engineering offices in Thief River Falls, Minn.
The lab comprises several components, the largest being the sound chamber. The two-foot-thick double walls and ceiling are a combination of baffles and foam. A snowmobile sits in the center of the room, on a chassis dyno that can simulate riding variables, surrounded by microphones.
The design of the room allows sound to go nowhere, which allows the team to hear the snowmobile in its rawest form. Whistle in the room, and it sounds dead and hollow. No reflection.
Sound is different if it’s measured on a flat bed of ice versus fluffy snow, Holalkere said, adding that noise generated on the dyno in the sound chamber represents snowmobile noise at its most severe. “If we can make them quieter on the dyno, we can easily extrapolate that it would be quieter in a snow situation, since snow absorbs sound,” he said.
The Sound Quality Room will be used to create and evaluate sounds from Arctic Cats and other machines, with the goal of finding a unique Arctic Cat sound.
They’re not going for a one-sound-fits-all scenario, Lusignan said. “The high-performance rider will want something with an edge, but as for a goal sound, it depends on the segment and the demographics.”
Various snowmobile sounds will be evaluated by market research groups comprised of snowmobilers.
“How sound is perceived is subjective, and we want to transfer it to an objective number,” Holalkere said. “We’ll play the kinds of sound generated in the field and let them tell us what they like and don’t like. We’ll look at the sound signature and put it into a matrix.”
Acoustics specialists
Holalkere has a background in sound, a Masters degree he holds in mechanical engineering with an emphasis in advanced vibration and acoustics. He came to Cat in 2002 after 10 years in the automotive industry and work in the construction and agricultural equipment industry.
When he arrived at the company, he had no experience with snowmobiles. Neither did the other NVH engineers, all experts in noise and vibration. “I think the company wanted out-of-the-box ideas,” he said. “Having a generic expertise in solving problems in vehicles that move is an advantage.”
The NVH engineers and the design team will work together closely, Holalkere said, “because what we do may affect the flow of something else.”

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