The primary reason for noise monitoring within motorsport is potential disturbance within local residential areas. Increasing regulation, changing public perception and more events each year has led to noise becoming a major issue within the motorsport community and one which has led to the closure of events and even race-tracks themselves!
Castle has been involved in the measurement of vehicle noise for many years which has included a lot of work with motor sport organisations in the UK and dealings with various race circuits. This has given the company an insight into the problems faced and has led to the development of potential solutions.
There are two ways in which the noise from motorsport is measured, depending on the venue/organisation. Firstly, the overall noise can be monitored at or near the boundaries of an event to keep an eye on the potential for disturbance or at least to monitor against any pre-agreed maximum permitted levels. This would usually be an agreement between the event organisers and the local authorities.
The equipment to do this can be a hand held meter, so long as it measures Leq such as the Castle GA116I or Ga216I (SONUS Sound Meter) or it can be done with a semi-permanent system such as the SONUS boxed system (SONUS Weatherproof System).
Secondly, and this is most important for road events like rallying or street based races, the noise of each car can be checked prior to the event as part of the normal safety checks.
This involves measuring the maximum noise level at 0.5m from the exhaust and at a 45 degree angle as shown in the diagram below. This noise level is the maximum sound pressure level (Lmax), normally taken at ¾ max power rpm for that engine. As this can sometimes be difficult to calculate on the spot, event organisers tend to manage this in different ways. For example, if the cars are in one or just a few classes then the rpm can be set for each class just to keep things simple. Alternatively, a guide can be produced covering the cars expected at the event.
For this kind of measurement, you can use the GA216I or GA116I as mentioned above and as shown in the picture on the left.