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  • Acoustical Society of America (ASA)  (2)
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  • Acoustical Society of America (ASA)  (2)
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  • 1
    Online Resource
    Online Resource
    Factors affecting the performance of large-aperture microphone arrays
    Acoustical Society of America (ASA) ; 2002
    In:  The Journal of the Acoustical Society of America Vol. 111, No. 5 ( 2002-05-01), p. 2140-2157
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 111, No. 5 ( 2002-05-01), p. 2140-2157
    Abstract: Large arrays of microphones have been proposed and studied as a possible means of acquiring data in offices, conference rooms, and auditoria without requiring close-talking microphones. When such an array essentially surrounds all possible sources, it is said to have a large aperture. Large-aperture arrays have attractive properties of spatial resolution and signal-to-noise enhancement. This paper presents a careful comparison of theoretical and measured performance for an array of 256 microphones using simple delay-and-sum beamforming. This is the largest currently functional, all digital-signal-processing array that we know of. The array is wall-mounted in the moderately adverse environment of a general-purpose laboratory (8 m×8 m×3 m). The room has a T60 reverberation time of 550 ms. Reverberation effects in this room severely impact the array’s performance. However, the width of the main lobe remains comparable to that of a simplified prediction. Broadband spatial resolution shows a single central peak with 10 dB gain about 0.4 m in diameter at the −3 dB level. Away from that peak, the response is approximately flat over most of the room. Optimal weighting for signal-to-noise enhancement degrades the spatial resolution minimally. Experimentally, we verify that signal-to-noise gain is less than proportional to the square root of the number of microphones probably due to the partial correlation of the noise between channels, to variation of signal intensity with polar angle about the source, and to imperfect correlation of the signal over the array caused by reverberations. We show measurements of the relative importance of each effect in our environment.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.1471895
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2002
    detail.hit.zdb_id: 1461063-2
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    Online Resource
  • 2
    Online Resource
    Online Resource
    The Huge Microphone Array (HMA)
    Acoustical Society of America (ASA) ; 1997
    In:  The Journal of the Acoustical Society of America Vol. 101, No. 5_Supplement ( 1997-05-01), p. 3119-3119
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 101, No. 5_Supplement ( 1997-05-01), p. 3119-3119
    Abstract: The Huge Microphone Array (HMA) is a collaborative effort between Brown University and Rutgers University that started in February 1994 to design, construct, debug, and test a real-time 512-microphone array system and to develop algorithms for use on it. Analysis of known algorithms made it clear that signal-processing performance of over 6 Gigaflops would be required; at the same time, there was a need for ‘‘portability,’’ i.e., fitting into a small van, that also set an upper limit to the power required. It was essential that the array be able to be used in both large and small acoustic environments. These tradeoffs and many others have led to a unique design in both hardware and software. The hardware uses 128 fast, floating-point DSP microprocessors and is designed so that data flow is independent of data processing. This leads to an unusually simple software environment. This paper presents the full design and its justifications. Performance for a few important algorithms relative to usage of processing-capability, response latency, and difficulty of programming is discussed. [Work supported by NSF Grant MIP-9314625.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.418967
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 1997
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
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    Online Resource
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