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Generating Nonstationary Multisensor Signals
under a Spatial Coherence Constraint

E.A.P. Habets, I. Cohen and S. Gannot

Abstract

Noise fields encountered in real-life scenarios can often be approximated as spherical or cylindrical noise fields. The characteristics of the noise field can be described by a spatial coherence function. For simulation purposes, researchers in the signal processing community often require sensor signals that exhibit a specific spatial coherence function. In addition, they often require a specific type of noise such as temporally correlated noise, babble speech that comprises a mixture of mutually independent speech fragments, or factory noise. Existing algorithms are unable to generate sensor signals such as babble speech and factory noise observed in an arbitrary noise field. In this paper an efficient algorithm is developed that generates multisensor signals under a predefined spatial coherence constraint. The benefit of the developed algorithm is twofold. Firstly, there are no restrictions on the spatial coherence function. Secondly, to generate M sensor signals the algorithm requires only M mutually independent noise signals. The performance evaluation shows that the developed algorithm is able to generate a more accurate spatial coherence between the generated sensor signals compared to the so-called image method that is frequently used in the signal processing community.

Status

Published in the Journal of the Acoustical Society of America, Vol. 124, Issue 5, pp. 2911-2917, Nov. 2008.

Babble Speech Example

The input signals are constructed using a single-channel babble speech recording that can be found here. For this example, the single-channel signal was downsampled to 8 kHz and four (non-overlapping) segments were used. The multisensor babble speech signals were generated using the MATLAB script "gen_babble_speech.m", which can be found in the package below. In total four sensor signals were generated with an inter sensor distance of 10 cm. The spatial coherence between sensors (1,2) and (1,3) are shown in Fig. 1. The resulting sensor signals can be found here (note that this wav-file contains 4 channels). These signals can be used as additive noise components for the evaluation of multimicrophone speech enhancement algorithms.


Fig. 1 Spatial coherence between two sensor pairs with an inter sensor
distance of 10 and 20 cm, respectively.

Download

MATLAB implementation of the developed algorithm (version 20090821).

Related Papers

BibTex Entry

@ARTICLE{Habets2008,
  author = {E. A. P. Habets and I. Cohen and S. Gannot},
  title = {Generating nonstationary multisensor signals under a spatial coherence constraint},
  journal = J_ASA,
  year = {2008},
  volume = {124},
  pages = {2911--2917},
  number = {5},
  month = nov,
  doi = {10.1121/1.2987429},
}

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