Near-field null and beamforming
First Claim
1. An electronic device comprising:
- a speaker; and
a microphone array comprising;
a first microphone positioned a first distance from the speaker;
a second microphone positioned a second distance from the speaker, wherein the first and second microphones are configured to receive an acoustic signal;
a complex vector filter coupled to the second microphone, wherein the complex vector filter is applied to an output signal of the second microphone to generate an acoustic sensitivity pattern for the array that provides an acoustic null at the location of the speaker;
a first delay circuit coupled to the second microphone;
a first difference circuit coupled to the first delay circuit and the first microphone;
a multiplier circuit coupled to the output of the first difference circuit;
a second difference circuit coupled to the output of the multiplier circuit;
a second delay circuit coupled to the first microphone;
a third difference circuit coupled to the second delay circuit and an output of the complex vector filter, wherein the output from the third difference circuit is provided to the second difference circuit; and
a beamforming circuit coupled to the output of the second difference circuit, wherein the beamforming circuit is configured to form an acoustic sensitivity pattern for the array by adjusting values for the complex vector filter or the multiplier circuit.
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Accused Products
Abstract
Devices and methods are disclosed that allow for selective acoustic near-field nulls for microphone arrays. One embodiment may take the form of an electronic device including a speaker and a microphone array. The microphone array may include a first microphone positioned a first distance from the speaker and a second microphone positioned a second distance from the speaker. The first and second microphones are configured to receive an acoustic signal. The microphone array further includes a complex vector filter coupled to the second microphone. The complex vector filter is applied to an output signal of the second microphone to generate an acoustic sensitivity pattern for the array that provides an acoustic null at the location of the speaker.
49 Citations
19 Claims
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1. An electronic device comprising:
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a speaker; and a microphone array comprising; a first microphone positioned a first distance from the speaker; a second microphone positioned a second distance from the speaker, wherein the first and second microphones are configured to receive an acoustic signal; a complex vector filter coupled to the second microphone, wherein the complex vector filter is applied to an output signal of the second microphone to generate an acoustic sensitivity pattern for the array that provides an acoustic null at the location of the speaker; a first delay circuit coupled to the second microphone; a first difference circuit coupled to the first delay circuit and the first microphone; a multiplier circuit coupled to the output of the first difference circuit; a second difference circuit coupled to the output of the multiplier circuit; a second delay circuit coupled to the first microphone; a third difference circuit coupled to the second delay circuit and an output of the complex vector filter, wherein the output from the third difference circuit is provided to the second difference circuit; and a beamforming circuit coupled to the output of the second difference circuit, wherein the beamforming circuit is configured to form an acoustic sensitivity pattern for the array by adjusting values for the complex vector filter or the multiplier circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of operating an electronic device to functionally provide an acoustic near-field unidirectional microphone and a far-field omnidirectional microphone, the method comprising:
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receiving an acoustical signal at an acoustic transducer array, wherein the acoustic transducer array comprises at least a first and a second microphones; generating a plurality of electrical signals, wherein each microphone of the acoustic transducer array generates an electrical signal; filtering at least one of the electrical signals according to the complex vector such that the output is defined by filtering at least one of the electrical signals according to the complex vector such that the output is defined by
Y(ω
,θ
)=|S(ω
)|√
{square root over ((A2+1)−
2A cos φ
)},wherein S is the acoustic signal, ω
is the frequency of the signal S, θ
is an angle of propagation of the signal S, k is a wave number, d is the distance between a first and second microphones, Φ
=kd(1+cos θ
), and A is a gain factor,wherein filtering generates an acoustical sensitivity pattern for the acoustical transducer array that provides a near-field null. - View Dependent Claims (18, 19)
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Specification