New Techniques for Microphone Array Systems: A Wireless Array and a Phase-based Talker Isolation Algorithm

Shakya, Rahul Ratna

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Year:: 2017
Contributor:: Shakya, Rahul Ratna (creator); Silverman, Harvey (Advisor); Rosenstein, Jacob (Reader); Brandstein, Michael (Reader); Brown University. Engineering: Electrical Sciences and Computer Engineering (sponsor)
Genre:: theses
Subject:: Microphone arrays; Blind source separation; Signal processing--Digital techniques; Microphone--Calibration
Extent:: 11, 110 p.
DOI: https://doi.org/10.7301/Z0QN657M

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Abstract:: Over the years, advancements in microphone and computing technologies have simplified microphone-array-system architectures and allowed for more complex algorithms. However, arrays are virtually always wired. For large arrays, the wiring of the microphones to a processing unit can be complex, time-consuming to implement, and is almost always fixed to a room. In this thesis, we present our new system - the ‘Wireless Microphone Array’. It comprises of battery-operated individual microphone units that transmit data over Wi-Fi to a central PC. The system also includes a separate wireless timer beacon that helps synchronize all microphone signals. We also describe a new process to calibrate the array, i.e. determine all the microphone locations, in which inter-unit distances are determined by utilizing the speakers onboard each unit, and microphone positions are hence derived by minimizing a maximum-likelihood estimator. Steps to ensure accurate distance measurements and detect erroneous measurements have also been proposed for the new procedure. The calibration process is quick and is fully automated, thus allowing the array to be easily reconfigured and used in any new room or placement. Microphone arrays have been used for a variety of applications such as speech enhancement, acoustic source localization/tracking, and source separation. The second continuation of this thesis focuses on the problem of isolating a single desired-talker from a multi-talker mixture. Based on the fact that competing speech signals are likely disjoint in the time-frequency domain, we present a time-frequency masking algorithm to isolate a desired-talker. The algorithm requires only the location of the target, and masks are generated based solely on phase information from the cross-correlations of microphone signals. A theoretical analysis for anechoic/echoic conditions, and for cases with beamforming errors are presented. We also introduce additional correction and softening stages to reduce any musical and click noises that may be introduced due to misassigned time-frequency points, and the sparsity of the mask. We provide performance results for the phase-based mask using both simulated recordings and real recordings made in an office environment room with a T60 of 0.55 seconds.
Notes:: Thesis (Ph. D.)--Brown University, 2017

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Rights: In Copyright
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Citation

Shakya, Rahul Ratna, "New Techniques for Microphone Array Systems: A Wireless Array and a Phase-based Talker Isolation Algorithm" (2017). Electrical Sciences and Computer Engineering Theses and Dissertations. Brown Digital Repository. Brown University Library. https://doi.org/10.7301/Z0QN657M

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Electrical Sciences and Computer Engineering Theses and Dissertations

Theses and Dissertations for the Electrical Sciences and Computer Engineering department.
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