Experimental reconstruction of non-stationary sound and vibration sources by means of Transient Planar Near-field Acoustic Holography

A novel algorithm called Transient Planar Near-field Acoustic Holography is presented to analyse nonstationary sound and vibration sources. The method is able to obtain the time-dependent pressure, particle velocity and intensity field at the source plane without any pre-knowledge of the source by inverse propagation of measured pressure fields. This makes it possible to analyse phenomena like transients and run-ups for all kinds of vibrating and sound radiating objects. Transient responses of thin plates are analysed to experimentally validate the performance of the algorithm. The determined velocity at the center of the plate is validated using a laser vibro-meter directed at the center of the plate and the spatial fields are qualitatively compared with theoretical mode shapes. It is shown that the algorithm is able to analyse transient responses of plates with good quantitative as well as qualitative results.