Method for the indirect measurement of acoustic power emitted by synchronous belts

One of the main problems in direct measurement of synchronous belt noise is the considerable level of disturbing acoustic emission produced by other components of the transmission. This causes uncertainty when measuring the sound power specifically emitted by the belt. In recent years there have been only a few systematic studies on noise emission mechanisms and some noise causes have been identified. In this paper a method on how to investigate single noise causes is proposed. The methodology developed consists of two distinct phases. In the former, aboustic power emission is measured by means of acoustic intensity techniques. In the latter, an acoustic prediction is performed by using a Scanning Laser Doppler (SLDV) Vibrometer and data processing routines based on the superposition principle and on commercial Boundary Element codes. The SLDV is utilized for its non-intrusivity and capability of in-operation data measurement on the running belt. The results obtained in the two phases are compared to evaluate the influence of the vibratory behaviour on the total acoustic emission experimentally determine.