Noise source identification on rolling tires by sound intensity measurement.

Abstract

The sound radiation characteristics of actually rolling tires with three types of the tread patterns were measured by the 2-microphone sound intensity technique. The measure mentswere performed at a test course in Japan Automobile Research Institute, in which a special trailer equipped with an automatic microphone scanning system was used and the normal sound intensity distribution in a plane parallel to the sidewall of a tire was measured during actual running. The results show that it is possible to identify the source positions on a tire actually rolling on a road surface by means of the soundin tensity technique. In the case of a rib tire, the noise was mainly generated from the leading and the trailing edges, not from the contact patch, while in the case of a lug tire, the main source position was the contact patch. The noise radiation pattern varied according to the difference of tread pattern. Further, the sound power radiated by three kinds of tires were compared. A-weighted sound power level of the lug tire is the biggest among them.