Beamforming in a reverberant environment using numerical and experimental steering vector formulations

Fischer, Jeoffrey; Doolan, Con J.

doi:10.1016/j.ymssp.2016.12.025

Cited by 27 publications

(10 citation statements)

References 13 publications

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“…The steering vector represents the transfer functions from the focus point to the microphone positions and account for the phase shift and amplitude correction (sound propagation model) as well as the microphone weighting [2]. They can be either obtained by measurements [3] or by theoretical models. In [4], different steering vector formulations are discussed.…”

Section: Beamforming Based Algorithmmentioning

confidence: 99%

“…In such cases, the steering vectors have to be adapted to take the reverberant environment into account. Two approaches are considered in [3]: (1) modeling reflections by a set of monopoles located at the image source positions; (2) experimentally based identification of Green's function. Thereby, the best results could be obtained by using the formulation with the experimentally obtained Green's functions.…”

Section: Limitations and Challengesmentioning

confidence: 99%

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Sound source localization – state of the art and new inverse scheme

Gombots

Nowak

2021

Elektrotech. Inftech.

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Acoustic source localization techniques in combination with microphone array measurements have become an important tool for noise reduction tasks. A common technique for this purpose is acoustic beamforming, which can be used to determine the source locations and source distribution. Advantages are that common algorithms such as conventional beamforming, functional beamforming or deconvolution techniques (e.g., Clean-SC) are robust and fast. In most cases, however, a simple source model is applied and the Green’s function for free radiation is used as transfer function between source and microphone. Additionally, without any further signal processing, only stationary sound sources are covered. To overcome the limitation of stationary sound sources, two approaches of beamforming for rotating sound sources are presented, e.g., in an axial fan.Regarding the restrictions concerning source model and boundary conditions, an inverse method is proposed in which the wave equation in the frequency domain (Helmholtz equation) is solved with the corresponding boundary conditions using the finite element method. The inverse scheme is based on minimizing a Tikhonov functional matching measured microphone signals with simulated ones. This method identifies the amplitude and phase information of the acoustic sources so that the prevailing sound field can be with a high degree of accuracy.

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Section: Beamforming Based Algorithmmentioning

confidence: 99%

Section: Limitations and Challengesmentioning

confidence: 99%

Sound source localization – state of the art and new inverse scheme

Gombots

Nowak

2021

Elektrotech. Inftech.

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“…However, analytical formulations of the Green function in flows are only available for uniform free flows. In the presence of boundaries (such as in closed wind tunnels), an image source model can be used to estimate the Green function [29]. In the case of free shear flows (such as in open wind tunnels), some approximations of the time delays can be obtained from the classical model of Amiet [2], but this model is not well-adapted to jet-type and/or arbitrary anisothermal flows.…”

Section: Beamforming With Ray Tracingmentioning

confidence: 99%

Array processing for the localisation of noise sources in hot flows

Rakotoarisoa

Marx

Prax

et al. 2019

Mechanical Systems and Signal Processing

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This paper investigates the problem of localizing a sound source in a heated flow using a microphone array. Applications are found in studies dealing with the identification of sound sources in hot turbulent jets, or with the sound radiation from installed turbofans. Two configurations have been investigated: a shear layer flow (wind-tunnel type) and a jet flow. In the present study acoustic data are generated using a simulation based on the Linearized Euler Equations. For heated flows, refraction by temperature gradients is superimposed with refraction by velocity gradients, and the objective of this study is to assess whether this effect is important and how it can be accounted for in different source localisation methods. For this purpose, a time-reversal-based imaging method has been compared with a beamforming-based method in which the time-delays are computed based on ray tracing. For the shear flow, the results show that for high subsonic Mach numbers and steep thermal gradients, the thermal stratification must be taken into account to ensure a satisfactory precision of localisation for both methods. However, including the gradients of velocity and temperature is less crucial for imaging sound sources in the jet flow. The results indicate also that the localisation error is lower with the beamforming and ray-tracing technique than with the time-reversal technique, the latter being more sensitive to the limited array aperture.

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“…Another approach developed by Sijtsma [16] consist in reducing the influence of virtual sources based on their coherence with real one. On a another side, Fisher [17] experimentally characterized his test section impulse response and used it in the beamforming process rather than the free-field Green function. Under the constrain of using a very fine mesh, Fisher shows the relevance of the method which overcome IMS in his case.…”

Section: A Contextmentioning

confidence: 99%

S1MAWind Tunnel New Aeroacoustic Capability: a Traversing Microphone Array

Nicolas¹,

Rey²

2018

2018 AIAA/CEAS Aeroacoustics Conference

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This paper aims at describing the new measurement device installed in S1MA wind tunnel for aeroacoustics tests. We present here the in-situ qualification of a traversing microphone array which equipped the acoustic closed test section of the wind tunnel. First, we show that it allows us to capture very complex directivity patterns thanks to a very good spatial resolution. Secondly, we demonstrate the ability of continuous scans measurements to perform as well as stabilized acquisitions, leading to a major improvement in wind tunnel productivity. Finally, we also take advantage of the microphone array to denoise acquisition data using beamforming processing.

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Beamforming in a reverberant environment using numerical and experimental steering vector formulations

Cited by 27 publications

References 13 publications

Sound source localization – state of the art and new inverse scheme

Sound source localization – state of the art and new inverse scheme

Array processing for the localisation of noise sources in hot flows

S1MAWind Tunnel New Aeroacoustic Capability: a Traversing Microphone Array

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