Sound testing

[dele]

Morning all,

Ive got a Db meter im borrowing from work, ive never been to a trackday and im suspect that my exhaust is going to be too loud, i hope to do a rough test here at home before i go

Can anyone tell me the standard way they perform noise tests?

Thanks

[motco]

MSA said:

“12.17.8. Sound Test Requirements. Measurements will be made at 0.5m from the end of the exhaust pipe with the microphone at an angle of 45° with the exhaust outlet and at a height of 0.5 to 1.0m above the ground. Where more than one exhaust outlet is present, the test will be repeated for each exhaust and the highest reading will be used. In circumstances where the exhaust outlet is not immediately accessible, the test may be conducted at 2.0m from the centre line of the vehicle at 90° to the centre line of the vehicle, with the microphone 1.2m above the ground. Measurements should be made outdoors with no large reflecting objects (e.g. walls etc.) within 3.0m (in the 0.5m test) or within 10.0m (in the 2.0m test). Background sound

levels should be at least 10dB(A) below the measured level.



Where possible measurements should be taken as close as possible to the vehicle, at the defined distances, to avoid background noise. Cars of periods A to D falling within Sections C and D should run engines at two thirds maximum RPM. The 2.0m test can be made from either side of the car. The highest reading registered being the one needing to comply with the maximum noise requirements.”

[GC8]

Make sure that you use the correct 'loading' too. Most dB meters will have two options.

The static test will usually be easy enough to pass, but the drive-by can catch you out, especially if you drive a turbocharged car, whichll be off-boost in the static test...