Acoustical characterization of vibrating structures by non contact measurement techniques: application to loudspeaker diaphragm

: The underlying objective of this work is to propose a technique for the measurement of the acoustical power, emitted from a vibrating surface, by non-contact vibration measurements. In order to calculate the acoustical power from vibration measurements, some different approaches have been proposed. Those techniques are here used to process the vibration field measured by a laser scanning vibrometer. Laser techniques open up new possibilities because of their high spatial resolution and their non intrusivity. An acoustical intensity measurement system has been employed to validate results obtained from the processing of the vibration data. In this paper the technique has been applied to calculate the acoustical power emitted from a loudspeaker diaphragm. The loudspeaker was mounted on a rigid panel and the measurement of sound intensity has been performed in a grid placed in front of the loudspeaker.