Best way to measure DB of bike

[grant965]

Hi all, what is the most accurate way of measuring how loud my exhaust is whilst riding. I have only been using the app on my phone and I had it in my outside pocket with the front of the phone (and presumably the mic) facing outwards.
It came back at 101, but thought it would be a lot higher as that is still within the legal limit?
Grant
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Ex bikes: 05 Suzuki En 125, '98 Yamaha Thundercat, '08 Honda cbr125, '05 Kawasaki z750, '03 Triumph Daytona 600, '91 Kawasaki ex250, '03 Hyosung Comet 125
Current Bike: '02 Suzuki TL1000R

[MarJay]

has to be measured behind the bike, approximately 50cm from the exhaust outlet at an oblique angle.

That's what they do at MSV circuits anyway.
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F; Cheap project: CBR900RR FireBlade
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[Ja7]

Is that a free app ?

[P.addy]

[Ariel Badger]

Phone apps are just for fun, proper sound testing is done with serious kit and as said above at 2/3 revs at about half a meter and at an oblique angle.
Most tracks work on 105 Db max, Brighton Speed Trials are 110 Db.
They also put a sort of spring on your can during the test that vibrates, this may or may not measure your revs.
However the law says that your pipe should be no louder than factory (or it used to).
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[supZ]

[P.addy]

Nice to know, ta!

[i.p.phrealy]

Ride Faster, noise will be behind you! Innit!

oh, and on a serious note, Maplin used to do a fairly accurate hand held decibel meter, don't know if they still do.
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and if you just tried you need professional help.
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[andyscooter]

we use the maplin decibel meter at the track

we work to 84 at a range of 30cm behind the bike on the 125s and a bit higher on the 250s

most four stroke 450s had to be banned as they were too loud and we were getting 140 odd decibels at a range of 50 metres and then the enviromentel health got called and we lost ten meets a year
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[Ariel Badger]

[Red Devil]

[Acemastr]

[Ariel Badger]

click
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Bikers make great organ donors, get 115 on your licence today.

[bazza]

[MarJay]

[sidewinder]

I have a decent idea for once Might be worth popping into a decent music shop they will have quality db meters to measure any kit they hire out .pop them a few quid i'm sure they will take a reading of your bike for you
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"Nitrous is like a cheap hooker, you want to hit it but are scared of the consequences

[Souleh]

Guys im a race event sound tester.

For testing, hold the DB meter at 50cm and 45degrees from the exhaust with any wind direction blowing engine noise AWAY from the meter (Aka back up the exhaust)

For RPMs see here

https://www.clubmsv.com/bike-testing-noise-limits

Any questions ask away

[Kickstart]

Hi

There is more than one DB scale, so make sure you are using the right one (not sure but think the difference is how is biases noise levels from different frequencies).

Measuring in your pocket will be pretty meaningless. Way too much difference caused by position relative to the exhaust, and on top of that there is wind noise to screw up the readings.

For circuits they use a pretty crude reading, with the noise meter in a particular position relative the exhaust at some set rpm. The details may well vary between different circuits.

For road noise tests it is done very differently. Not really any chance of getting an accurate measure of that in a random place with a phone app.

All the best

Keith
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[Red Devil]

[WindyMiller]

[Walloper]

[i.p.phrealy]

[Walloper]