Bring It, Bose: Noise-Canceling Car Interiors
No, Bose can not shut up your screaming kids. But it may start making all of our interiors quieter.
Bose has stamped its italicized name nearly everywhere. If you’re a churchgoer, the minister is likely booming a sermon over Bose speakers. If you’re reading this article on the toilet in a nice hotel restroom, you’re probably hearing XM Watercolors from a Bose ceiling unit.
In cars, Bose systems are so commonplace -- they’re on offer from 20 different brands, from Mazda to Maybach -- that the idea of a high-end stereo isn’t so special anymore. In the early 1980s, when some of the first Bose car-audio systems debuted on Cadillacs and the Corvette, good factory sound didn’t exist. You had to rip everything out, go to Circuit City and slam the car with huge subs and tacky head units. Now that automakers realize car buyers will pay hundreds, if not thousands, for premium sound, we have car audiophiles arguing whether a Burmester is better than a Bowers & Wilkins or a Bang & Olufsen. We can also choose from Mark Levinson, ELS, Harman Kardon, Infinity and Shaker systems.
But while Bose has plenty of competition, the company’s most promising advances have nothing to do with reproducing sweet music. It’s silencing the nasty vibrations from today’s engine-bogging transmissions and making engines sound better, all through smart electronics built into the stereo. I asked John Pelliccio, manager of technical product marketing for Bose Automotive, about where these technologies are headed.
Noise cancellation , a feature Bose helped to pioneer for commercial pilots in the late 1980s, is now entering the car interior. Cadillac will offer Bose active noise cancellation on the upcoming ATS and XTS sedans, as will Buick on the compact Encore. The idea is to place microphones throughout the cabin, listen for offending frequencies and then play back those unwanted sounds – inverted – through the stereo speakers. The graph, pictured above from Bose, shows decibels over an rpm range of 1,000 to 5,000; noise cancellation, when switched on, is shown in blue.
General Motors adapted its own system on 4-cylinder models of the current Chevrolet Equinox in order to block the booming vibrations normally heard when the engine stays at low revs. I recently tested a 2012 Volkswagen Tiguan and Range Rover Evoque, and trust me, those “booms” still haunt my eardrums.
While I’m not convinced until I hear a “before and after” test on the same car, active noise cancellation looks to be the easiest shortcut to improve NVH (industry-speak for noise, vibration and harshness). It’ll become a cheaper way to develop quieter, potentially more fuel-efficient cars -- sound-deadening material and acoustic glass add considerable weight and cost -- that can be added at any point in development without requiring a total redesign. Plus, as more automakers shift to direct injection (a noisier, high-pressure fuel line), auto start/stop (which tends to cause low-frequency shuddering) and even diesel engines (which clatter at idle), noise cancellation will be sorely needed.
Says Pelliccio: “If you fine-tuned the insulation and pipes and valves and all these other things -- if you fine-tuned the engine to sound a certain way -- and the CEO hops in the car and says ‘You know, I’m not crazy about the way it sounds, can you change it?’ You can’t, without a lot more engineering and a lot more time. ”
How much time would the Bose process take? Pelliccio estimates an automaker’s NVH team could target and fix the bad sounds in a matter of “hours or days versus weeks or months.” Better still, Bose will sell its noise-cancellation feature to work with any automaker’s audio system, with or without Bose speakers. The company would not say what other automakers, other than GM, were interested in the technology.
Bose has also been treading -- very cautiously, after the controversial music of the new BMW M5 -- with “sound enhancement,” which is essentially noise cancellation in reverse. In the M5, BMW found its interior too insulated and the twin turbos so muffling that a recording of the engine’s exterior sound plays through the stereo, synced with actual revs. Other automakers must be watching BMW’s experiment, too. So far, Bose says it has no takers for this system.
“We’re offering the [automakers] tools that they can use to be able to change their engine sound, but we’re very careful about not offering specific engine sounds,” Pelliccio said.
Then again, trusty, old-fashioned piping seems to do the trick quite well. Porsche built a “sound symposer” for the new 911, which channels engine music through the interior with an actual pipe connected to the intakes. Electronically controlled muffler baffles, organ-style vents that open the exhaust pipes at higher revs, expel glorious noise like on the Corvette. Or, you can enjoy the resonator pipe Ford built into the Mustang GT.
But making nice noise is easy. All you have to do is roll down the windows in a tunnel and floor the throttle. To filter unwanted noise, well, that's easy, too. I’m going to try driving with my Audio-Technica QuietPoint headphones. We can’t all afford Bose, OK?
Clifford Atiyeh has spent his entire life driving and riding in cars he doesn't own. He was raised in Volvos and has grown to love fast, irresponsible vehicles of all kinds. He lives in Boston, is a member of the New England Motor Press Association, and has reported for The Boston Globe, Car and Driver, Popular Mechanics and The Times of London.
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