ULTRA SMALL MICROPHONE ARRAY
First Claim
1. A method for digitally processing a signal from an array of two or more microphones M0 . . . MM, the method comprising:
- producing a discrete time domain input signal xm(t) from each of the two or more microphones M0 . . . MM, where M is greater than or equal to 1;
determining a listening direction of the microphone array;
using the listening direction in a semi-blind source separation to select a set of N finite impulse response filter coefficients bi, where N is a positive integer.
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Abstract
Methods and apparatus for signal processing are disclosed. A discrete time domain input signal xm(t) may be produced from an array of microphones M0 . . . MM. A listening direction may be determined for the microphone array. The listening direction is used in a semi-blind source separation to select the finite impulse response filter coefficients b0, b1 . . . , bN to separate out different sound sources from input signal xm(t). One or more fractional delays may optionally be applied to selected input signals xm(t) other than an input signal x0(t) from a reference microphone M0. Each fractional delay may be selected to optimize a signal to noise ratio of a discrete time domain output signal y(t) from the microphone array. The fractional delays may be selected to such that a signal from the reference microphone M0 is first in time relative to signals from the other microphone(s) of the array. A fractional time delay Δ may optionally be introduced into an output signal y(t) so that: y(t+Δ)=x(t+Δ)*b0+x(t−1+Δ)*b1+x(t−2+Δ)*b2+ . . . +x(t−N+Δ)bN, where Δ is between zero and ±1.
169 Citations
30 Claims
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1. A method for digitally processing a signal from an array of two or more microphones M0 . . . MM, the method comprising:
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producing a discrete time domain input signal xm(t) from each of the two or more microphones M0 . . . MM, where M is greater than or equal to 1;
determining a listening direction of the microphone array;
using the listening direction in a semi-blind source separation to select a set of N finite impulse response filter coefficients bi, where N is a positive integer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A signal processing apparatus, comprising:
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an array of two or more microphones M0 . . . MM wherein each of the two or more microphones is adapted to produce a discrete time domain input signal xm(t);
one or more processors coupled to the interface; and
a memory coupled to the array of two or more microphones and the processor, the memory having embodied therein a set of processor readable instructions for configured to implement a method for digitally processing a signal, the processor readable instructions including;
one or more instructions for determining a listening direction of the microphone array from the discrete time domain input signals xm(t); and
one or more instructions for using the listening direction in a semi-blind source separation to select filtering functions to separate out two or more sources of sound from the discrete time domain input signals xm(t). - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A method for digitally processing a signal from an array of two or more microphones M0 . . . MM, the method comprising:
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receiving an audio signal at each of the two or more microphones M0 . . . MM;
producing a discrete time domain input signal xm(t) from each of the two or more microphones M0 . . . MM;
applying one or more fractional delays to one or more of the time domain input signals xm(t) other than an input signal x0(t) from a reference microphone M0, wherein each fractional delay is selected to optimize a signal to noise ratio of an output signal from the microphone array and wherein the fractional delays are selected to such that a signal from the reference microphone M0 is first in time relative to signals from the other microphone(s) of the array. - View Dependent Claims (29, 30)
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Specification