Sound Advice

Investigation of HVAC cabin noise

Regulations, like Australian Vehicle Standard Rules, are in practice to control the level of noise emitted by vehicles. The Environment Protection Act (EPA) makes it an offence to own or use a vehicle which exceeds prescribed noise levels. Currently, there are no regulations in practice to limit the in-cabin vehicle noise, other than the manufacturer’s internal target levels. However, noise as part of Noise, Vibration and Harshness (NVH), driving comfort and quality of ride feeling were some of the criteria considered for the tests carried out by various organisations.

Consumer awareness is made through comprehensive road tests of new and used vehicles and the results are provided by various organisations across the world, in Australia by RACV. In these tests, noise is rated by subjective evaluation while driving the vehicle to check driving smoothness with respect to engine noise while at constant speed or acceleration and also aerodynamic noise intrusion. A measure of noise efficiency, the star rating system, has a minimum of one star (poor quality or noisy) and a maximum of five (excellent quality or very quiet), by means of which we can directly compare a great range of similar products from various manufacturers. For example, star ratings for the noise can be seen under performance and handling refinements in www.racv.com.au, www.whatcar.co.uk.