A study of the relevance of an acoustic holography method using wavelets based on features extracted from wavenumber spectra

摘要

The aim of the study is to find objective criteria that prove the relevance of a method using wavelets in Nearfield Acoustic Holography (NAH). The goal is to highlight the advantage of the method that involves reducing distortion in NAH reconstruction process. Indeed, NAH is very sensitive to truncation effects due to the finite size of the microphone array. These effects that influence the acoustic pressure field acquired in the nearfield of the noise sources are exaggerated on the back-propagated pressure field. Distortion introduced by truncation effects is hard to lessen by filtering in the domain of wavenumbers, even by using regularization methods. The wavelet treatment was experimented on three loudspeakers: one is close to the borders of the antenna. Visual comparisons were made between resulting acoustic fields for the studied frequency from wavelet treatment and from usual holography processing with filtering in the wavenumber spectrum. These comparisons show the advantage of the method. The present study gives more relevant objective criteria to argue for the use of the wavelet method in practical applications. Objective features based on distance measurements in the domain of wavenumbers are described.