Q&A - Noise & Motorcycle Mufflers

Q&A ImageI have a question regarding aftermarket motorcycle mufflers. What is the noise requirements or standards in BC for mufflers that are too loud and how should this be measured?

I actually heard one police officer say that any motorcycle muffler with a black coloured tip is illegal.

I have heard of motorcyclists being stopped and issued a Notice & Order to have the mufflers tested at an authorized inspection facility only to find that they are well within limits. This is after paying around $100.00 to have the inspection done.

Is there any way the motorcycle owner can test this themselves?

Comments

Answer

This is a popular topic as a quick search of "muffler motorcycle" shows. The noise levels referenced in the Motor Vehicle Act Regulations are part of those articles.

As for testing, there are at least two, one is at a designated inspection facility and the other is at the side of the highway. To complicate matters, the roadside would depend on whether the enforcement action is done under the MVAR or a bylaw. I will leave it to you to search for any bylaw that you are interested in as it is impractical for me to report on every municipality in BC.

If you were to buy your own decibel meter, you could test the sound levels of your motorcycle  yourself.

Just because a muffler has a black tip does not mean that it will be illegal. Perhaps what the officer is saying is that every muffler with a black tip that he has tested has failed.

It is possible that a motorcycle may be ordered to inspection and passes. The officer may not have been able to estimate the noise level properly and I have known facilities to pass vehicles that should not have been passed.

Measuring sound

Measuring sound is not as simple as say measuring temperature or weighing an object because sound changes in intensity depending on the distance from the source and objects that might reflect or absorb the sound waves. The formulae for describing the intensity of sound is Energy divided by (Time x Area). Reflecting sound will add to the intensity and absorbing will reduce the intensity. If I were to stand next to the motorcycle and hold the sound metre a foot away from the exhaust the reading I would get will be higher than if I turned around and held the metre in front of me and shielding it from the exhaust.

There should be a standard distance, height above ground and control for reflective or absorbing objects that is required for any measurement. The sound metres should be certified too. I would be suspect of the accuracy of any reading made on a roadside and unless the reading was some considerable amount over the limit I would think it should be challenged.

FWIW, sound is not linear. A reading of 90 dB is considerably more damaging to hearing than is 80. 90 will cause hearing loss. 140 dB is painful. 60 dB is roughly normal conversation and most people can hear down to zero. Young people can often hear down to -15 dB.

There are apps for smart phones and inexpensive metres that will do a reasonable job of measuring sound but will suffer from accuracy issues. However because sound is not linear as it increases you can be assured a reading more than 20 dB over the regulations or bylaw will likely fail a test conducted by a police officer.

Perhaps the police could charge a driver of a loud vehicle with assault when that driver uses ear plugs for protection but still subjects the public to damaging noise?

Noise and Motorcycle Mufflers

I took part in Transport Canada motorcycle noise certification tests at Boundary Bay Airport back in the 80's.  it was a very precisely-laid out test area with no reflecting sound surfaces within 150 metres, as I recall.  the tests required full-throttle acceleration over a 100 metre distance, with the measuring devices at the mid-point about 25 metres to the side, I believe.  this is pretty well impossible to duplicate on the roadside, and the police don't have the same equipment.  I was also part of a BC Motorcycle Federation project at about the same time aimed at sound testing of off-road motorcycles.  the test required the sound meter held at the same height as the exhaust outlet, at a distance of 1 metre and at a 45 degree angle to the side.  the certified meters cost us about $2500 at the time, but should be cheaper now.  this kind of test could be easily duplicated on the roadside, assuming the right equipment and a trained tester.  the hard part is knowing what dbA rating is appropriate and acceptable under this test procedure compared to the Transport Canada one for on-street certification.  I'm sure there's an engineer out there with those answers.

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