Adaptive near-field beamforming techniques for sound source imaging

Abstract

Phased array signal processing techniques such as beamforming have a long history in applications such as sonar for detection and localization of far-field sound sources. Two sometimes competing challenges arise in any type of spatial processing; these are to minimize contributions from directions other than the look direction and minimize the width of the main lobe. To tackle this problem a large body of work has been devoted to the development of adaptive procedures that attempt to minimize side lobe contributions to the spatial processor output. In this paper, two adaptive beamforming procedures-minimum variance distorsionless response and weight optimization to minimize maximum side lobes-are modified for use in source visualization applications to estimate beamforming pressure and intensity using near-field pressure measurements. These adaptive techniques are compared to a fixed near-field focusing technique ͑both techniques use near-field beamforming weightings focusing at source locations estimated based on spherical wave array manifold vectors with spatial windows͒. Sound source resolution accuracies of near-field imaging procedures with different weighting strategies are compared using numerical simulations both in anechoic and reverberant environments with random measurement noise. Also, experimental results are given for near-field sound pressure measurements of an enclosed loudspeaker.

Passive wideband source localization based on cylindrical focused beamforming in shallow water

“…The localization of narrowband source has been discussed in the literature, including many advanced source localization techniques, such as conventional beamforming algorithm, MUSIC, ESPRIT, and MVDR [1]. MVDR beamformer is one of the most widely used adaptive beamforming procedure, it can improve the accuracy of noise source localization and reduce side lobe contributions to the beamformer output [2], [3]. Several adaptive wideband source localization approaches has been developed in the literature recently, including the spatial-time-frequency-distributionbased method [4] and the coherent signal subspace method (CSM) [5].…”

Strategies to predict radiated sound fields from foldable, Miura-ori-based transducers for acoustic beamfolding

“…5,6 By virtue of acoustic reciprocity, delaying and shading received signals from microphone array transducers achieves similarly large increases in acoustic wave directionality for applications of environmental imaging and measurement. [7][8][9][10][11] Yet, the digital signal processing methods that enable such beamforming with active phase delays introduce particular challenges associated with the computational cost, filter stability, complexity of implementation, and limited portability of the beamformer and signal processing system. [12][13][14] These difficulties are exacerbated when real-time beam steering is required, particularly for high frequencies.…”

Near field broadband beam space antenna array processor for multiple Interference Canceler

“…Mostly the existing near field beamforming methods emphasize only on designing the specified array responses or optimizing the array gain for certain noise and interference environment as discussed in [3][4][5][6][7][8]. The distance discrimination and robustness against location errors is crucial for near field beamforming due to the difficulty in estimating near field signal locations especially the radial distances.…”

“…These situations arise, for example, in the application of microphone arrays to mobile telephony, video or teleconferencing in small rooms where the source is located in the array's near field. The near field beamforming using microphone arrays, where spherical wave propagation is applicable, has been discussed in [1][2][3][4][5][6][7][8][9] and has found wide applications in hands free phones, hearing aids, video and teleconferencing, speech input devices to computers etc.…”