On the use of modified phase transform weighting functions for acoustic imaging with the generalized cross correlation

Type de document

Études primaires

Année de publication

2019

Langue

Anglais

Titre de la revue

Journal of the Acoustical Society of America

Première page

1546

Dernière page

1555

Résumé

The generalized cross correlation (GCC) is an efficient technique for performing acoustic imaging. However, it suffers from important limitations such as a large main lobe width for noise sources with low frequency content or a high amplitude of side lobes for noise sources with high frequencies. Prefiltering operation of the microphone signals by a weighting function can be used to improve the acoustic image. In this work, two weighting functions based on PHAse Transform (PHAT) improvements are used. The first adds an exponent to the PHAT expression (ρ-PHAT), while the second adds the minimum value of the coherence function to the denominator (ρ-PHAT-C). Numerical acoustic images obtained with the GCC and those weighting functions are compared and quantitatively assessed thanks to a metric based on a covariance ellipse, which surrounds either the main lobe or the side lobes. The weighting function ρ-PHAT-C provides the smallest surface ellipses especially when the arithmetic of the GCC is replaced by the geometric mean (GEO). Experimental measurements are carried out in a hemi-anechoic room and a reverberant chamber where two loudspeakers were set in front of microphone array. The acoustic images obtained confirm that the ρ-PHAT-C with the GEO outperforms the GCC, GCC-PHAT, and GCC ρ-PHAT.

Mots-clés

Carte de bruits, Noise chart, Instrument de mesure, Measuring instrument, Propagation du son, Sound propagation, Description du matériel, Description of equipment, Évaluation du matériel, Evaluation of equipment, Lutte contre le bruit, Noise control, Préservation de l'ouïe, Hearing conservation, Mesure du bruit, Noise measurement, Microphone

Numéro de projet IRSST

2015-0075

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