Noise Test

Your car will also be subject to a static noise test. This may be carried out during scrutineering, or more likely as you line-up ready for first practice. The maximum static noise level for most events is normally 105 decibels.

Measurements will be made at 0.5m from the end of the exhaust pipe with the sound meter’s microphone at an angle of 45° with the exhaust outlet and at a height of 0.5 to 1.0m above the ground [Blue Book, J, 5.18.1]. You will be asked to raise the RPM of your engine to 2/3 of maximum RPM. If you fail to pass this test, then you will not be allowed to compete. If you think your car might be marginal, then before you enter an Event, go along to your local circuit during a Track Day and ask the Organisers to check your car. They will usually be quite happy to do so, even if you are not entered for an event on the day. Some tracks [mainly circuits] will have ‘Drive-by’ noise tests [normally 92dB at 20 metres and will monitor the noise of individual cars as they pass. You will be warned if your car infringes one of these tests which will result in a voided run and you might have to keep your RPM low and change up early if your noise exceeds the limit in the area of the ‘Drive-by’ test. Not ideal for setting competitive times!

Another noise procedure at some circuits is to ‘average’ the noise of all cars over a period of time. If the average noise rises above a certain level, then competition may be halted until the average level is deemed to have returned to normal. A bizarre turn of events where all activity is frozen and everyone sits quietly waiting…