Adaptive microphone array
DCFirst Claim
1. A method of enhancing the signal-to-noise ratio of a microphone array, the array including a plurality of microphones and having a directivity pattern, the directivity pattern of the array being adjustable based on one or more parameters, the method comprising the steps of:
- a. evaluating one or more parameters to realize an angular orientation of a directivity pattern null, which angular orientation reduces microphone array output signal level in accordance with a criterion, said evaluation performed under a constraint that the null be precluded from being located within a predetermined region of space which comprises a range of directions about the array, which range reflects a predetermined directional variability of the desired acoustic energy with respect to the array;
b. modifying output signals of one or more microphones of the array based on the one or more evaluated parameters; and
c. forming an array output signal based on one or more modified output signals and zero or more unmodified microphone output signals.
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Abstract
The present invention is directed to a method of apparatus of enhancing the signal-to-noise ratio of a microphone array. The array includes a plurality of microphones and has a directivity pattern which is adjustable based on one or more parameters. The parameters are evaluated so as to realize an angular orientation of a directivity pattern null. This angular orientation of the directivity pattern null reduces microphone array output signal level. Parameter evaluation is performed under a constraint that the null be located within a predetermined region of space. Advantageously, the predetermined region of space is a region from which undesired acoustic energy is expected to impinge upon the array, and the angular orientation of a directivity pattern null substantially aligns with the angular orientation of undesired acoustic energy. Output signals of the array microphones are modified based on one or more evaluated parameters. An array output signal is formed based on modified and unmodified microphone output signals. The evaluation of parameters, the modification of output signals, and the formation of an array output signal may be performed a plurality of times to obtain an adaptive army response. Embodiments of the invention include those having a plurality of directivity patterns corresponding to a plurality of frequency subbands. Illustratively, the array may comprise a plurality of cardioid sensors.
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Citations
23 Claims
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1. A method of enhancing the signal-to-noise ratio of a microphone array, the array including a plurality of microphones and having a directivity pattern, the directivity pattern of the array being adjustable based on one or more parameters, the method comprising the steps of:
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a. evaluating one or more parameters to realize an angular orientation of a directivity pattern null, which angular orientation reduces microphone array output signal level in accordance with a criterion, said evaluation performed under a constraint that the null be precluded from being located within a predetermined region of space which comprises a range of directions about the array, which range reflects a predetermined directional variability of the desired acoustic energy with respect to the array; b. modifying output signals of one or more microphones of the array based on the one or more evaluated parameters; and c. forming an array output signal based on one or more modified output signals and zero or more unmodified microphone output signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus for enhancing the signal-to-noise ratio of a microphone array, the array including a plurality of microphones and having a directivity pattern, the directivity pattern of the array being adjustable based on one or more parameters, the apparatus comprising:
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a. means for evaluating one or more parameters to realize an angular orientation of a directivity pattern null, which angular orientation reduces microphone array output signal level in accordance with a criterion, said evaluation performed under a constraint that the null be precluded from being located within a predetermined region of space which comprises a range of directions about the array which range reflects a predetermined directional variability of the desired acoustic energy with respect to the array; b. means for modifying output signals of one or more microphones of the array based on the one or more evaluated parameters; and c. means for forming an array output signal based on one or more modified output signals and zero or more unmodified microphone output signals. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification