#274 Measuring the Sound of Silence : The Noise Snare

Calgarians may not like Photo Radar, but at least they’ve had time to get used to automated stealth traffic control measures. Now, they can look forward to the Noise Snare.

Editor Campbell having just returned from the 2011 Hydrogen and Fuel Cell Conference and Exhibition in Vancouver, I’m sure we can expect more ink in CB about the electric revolution coming soon to the motorcycle industry. And while hydrogen can, of course, be used to fuel internal combustion engines, the future thrust of this technology is certain to be in using hydrogen fuel cells to power batteries and/or electric motors. After all, the internal combustion engine has had a pretty good run, but can never exceed its maximum theoretical energy conversion rate of less than 40 per cent. As such it won’t challenge electricity as the efficient future driving force.
Whether the long-term winner in on-board electricity will be hydrogen fuel cells topped up at the local gas bar, or a plug-and-play rechargeable battery, or a hybrid of the two remains to be seen. No doubt the existing gasoline industry would rather you topped up with H2-on-the-go because of their investment in the distribution infrastructure. But I remain to be persuaded that carrying a cryogenic gas tank and hydrogen fuel cells around on a motorcycle is a good idea.
Whichever technology prevails, one outcome is an absolute: cars and motorcycles of the future will be much quieter than they are now. Or will they?
Electric vehicles, of course, are inherently much quieter than gas powered autos—apart from tire noise, that is. In response to input from organizations representing those with impaired vision, several states in the US have introduced proposals to make hybrid and electric cars noisier, so that those with impaired sight can hear them approaching. In the UK, Lotus Engineering has produced a synthesized “engine sound” generator that can be fitted to electric cars to fulfill this need.
Electric motorcycles will likely be pretty quiet too, and motorcycles generate far less tire noise than a typical car. But the visceral appeal of “motorcycle sound,” as the industry likes to call it, is important to motorcycle buyers, so it’s almost certain some kind of noise generation system will get to be fitted to the electric Future Bike. But what kind of noise–and how much?
Though a race-tuned slip-on may sound great to a sportbike aficionado, and straight-through pipes may stir a Softailer’s soul, to 99 per cent of the population it’s just noise. And they’re getting pretty fed up with it.
It’s certain Edmonton, Alberta-based electrical engineer Mark Nesdoly’s experience isn’t unique. He was putting his young daughter to bed one night when a throttle-happy biker’s loud exhaust upset her nascent repose. Nesdoly determined to do something about excessive street noise. The result was the Noise Snare.
The Noise Snare works a bit like photo radar. A roadside receiver measures sound levels of passing vehicles, and if the noise exceeds a pre-set level, the Noise Snare snaps a picture of the vehicle’s licence plate. The miscreant’s ticket arrives shortly thereafter in the mail. Calgary looks set to be the first city in Canada to test the Sound Snare: last year, the City received 1,310 vehicle noise complaints—the third most common of all residents’ complaints. The city is planning to make a noise level of more than 96dB measured at the roadside an offence, and is using Noise Snare technology to enforce it.
There are, of course, existing bylaws in most jurisdictions about excessive vehicle noise, but these typically require a vehicle to be pulled over for some other offence before a noise test can be administered. And existing bylaws demand strict adherence to measurement criteria, including angle and distance from the exhaust. The Noise Snare, while less objective in its measurement, is more realistic in terms of assessing nuisance, because it measures sound pressure at street level.
It will come as no surprise that Calgary bikers are opposed to the Noise Snare, and equally predictably cite the old saw about loud pipes saving lives. However, there’s no objective, authoritative, published research that supports that position. After all, most motorcycle collisions, according to the Hurt report, involve the bike being hit from the front where exhaust noise is not a factor. Hurt concluded that “conspicuity” was easily the most important passive factor in preventing motorcycle collisions.
Every motorcyclist likes to hear their engine’s “voice.” But there’s a world of difference between the sotto voce purr of a correctly tuned exhaust and the rasp of open pipes, which sound to me more like chronic flatulence.
So are Termignioni, Akrapovic, Leo Vince and the rest working on sound synthesizers for electric motorcycles? If they are, they might want to consider keeping the volume down.

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