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In accordance with the present invention, a system and method for computing a location of an acoustic source is disclosed. The method includes steps of processing a plurality of microphone signals in frequency space to search a plurality of candidate acoustic source locations for a maximum normalize

In accordance with the present invention, a system and method for computing a location of an acoustic source is disclosed. The method includes steps of processing a plurality of microphone signals in frequency space to search a plurality of candidate acoustic source locations for a maximum normalized signal energy. The method uses phase-delay look-up tables to efficiently determine phase delays for a given frequency bin number k based upon a candidate source location and a microphone location, thereby reducing system memory requirements. Furthermore, the method compares a maximum signal energy for each frequency bin number k with a threshold energy Et(k) to improve accuracy in locating the acoustic source.

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1. A method for computing a location of an acoustic source, comprising the steps of:receiving acoustic signals from the acoustic source by an array of M-1 microphones and a reference microphone, each microphone identified by an integer microphone index m, 0?m?M-1; storing phase-delay look-up tables,

1. A method for computing a location of an acoustic source, comprising the steps of:receiving acoustic signals from the acoustic source by an array of M-1 microphones and a reference microphone, each microphone identified by an integer microphone index m, 0?m?M-1; storing phase-delay look-up tables, the phase-delay look-up tables based upon a plurality of candidate source locations and a spatial configuration of the array of microphones; and processing the received acoustic signals using the phase-delay look-up tables to compute the location of the acoustic source. 2. The method of claim 1, wherein an entry in a first phase-delay look-up table is defined by an algebraic expression D(r,m)=512·b·Δm·v, where r is a vector to a candidate source location of the plurality of candidate source locations, b is a frequency width, v is inversely proportional to a speed of sound, and Δm is a distance between a location of a microphone m and the candidate source location minus a distance between a location of the reference microphone and the candidate source location.3. The method of claim 1, wherein an entry in a second phase-delay look-up table is defined by an algebraic expression cos_table(j)=cos(π·j/256), where j is an integer index and 0?j511.4. The method of claim 1, wherein an entry in a third phase-delay look-up table is defined by an algebraic expression sin_table(j)=sin(π·j/256), where j is an integer index and 0?j?511.5. The method of claim 1, wherein the processing further comprises the steps of:processing each received acoustic signal to generate blocks of complex coefficients sampled in frequency, each complex coefficient of a block associated with a frequency bin number k, where 0?k?N-1; computing signal energies, a signal energy received by the array of microphones from a candidate source location of the plurality of candidate source locations for the frequency bin number k determined by multiplying a complex coefficient of a selected block from each received acoustic signal associated with a microphone m by an appropriate phase delay, summing the phase-delayed complex coefficients, and squaring the summation; and computing the location of the acoustic source by normalizing and summing the signal energies over the N frequency bin numbers for each candidate source location of the plurality of candidate source locations to give a total signal energy for each candidate source location. 6. The method of claim 5, wherein the processing further comprises the steps of:digitizing each received acoustic signal; segmenting each digitized signal into a plurality of blocks, each block of the plurality of blocks including N digital samples Xpm(n), each digital sample Xpm(n) identified by the integer microphone index m, an integer block index p, and an integer sample index n, where 0?n?N-1 and performing a discrete Fast Fourier Transform (FFT) on each block to transform the N digital samples per block to N complex coefficients Fpm(k) per block, where 0?k?N-1. 7. The method of claim 5, wherein the appropriate phase delay for the frequency bin number k, the candidate source location, and the microphone m is determined from a first phase-delay look-up table D(r,m), a second phase-delay look-up table cos_table(j), and a third phase-delay look-up table sin_table(j), where r is a vector to the candidate source location of the plurality of candidate source locations and j is an integer computed from an algebraic expression based upon the first look-up table and the frequency bin number k.8. The method of claim 5, wherein the computing the location of the acoustic source further comprises the step of determining a maximum total signal energy.9. A method for computing a location of an acoustic source, comprising the steps of:receiving analog signals from M-1 microphones and a reference microphone, each received analog signal and each microphone identified by an integer microphone index m, 0?m?M-1; digitizing each received analog signal to generate a plurality of digital samples; segmenting each digitized signal into a plurality of blocks, each block of the plurality of blocks including N digital samples of the plurality of digital samples and each digital sample of the N digital samples identified by the integer microphone index m, an integer block index p, and an integer sample index n, 0?n?N-1; performing a discrete Fast Fourier Transform (FFT) on each block to transform the N digital samples to N complex coefficients, a complex coefficient Fpm(k) of the N complex coefficients identified by the integer microphone index in, the integer block index p, and an integer frequency bin number k, 0?k?N-1; searching P blocks of each digitized signal for a maximum signal energy associated with the integer frequency bin number k, identifying a block p′ containing the maximum signal energy, 0?p′?P-1; comparing the maximum signal energy with a threshold energy Et(k), and if the maximum signal energy is less than the threshold energy, setting each complex coefficient of the P blocks of each digitized signal associated with the integer frequency bin number k equal to zero; determining a plurality of phase delays using look-up tables; multiplying each complex coefficient by a phase delay eiθm from the plurality of phase delays to generate phase-delayed complex coefficients and summing the phase-delayed complex coefficients over the integer microphone index m for a candidate source location (x,y,z) of a plurality of candidate source locations and for the integer frequency bin number k according to a first algebraic expression computing a normalized total signal energy for the candidate source location (x,y,z) according to a second algebraic expression; where 0?k1?kh?N-1 and S(k) is an approximate measure of signal strength for the integer frequency bin number k; anddetermining the location of the acoustic source based upon the normalized total signal energies computed for the plurality of candidate source locations. 10. The method of claim 9, wherein M=16.11. The method of claim 9, wherein N=640.12. The method of claim 9, wherein P=5.13. The method of claim 9, wherein an entry in a first look-up table is defined by an algebraic expression D(r,m)=512·b·Δm·v, where r is a vector to the candidate source location (x,y,z) of the plurality of candidate source locations, b is a frequency width of the integer frequency bin number k, v is inversely proportional to a speed of sound, and Δm is a distance between a location of a microphone m and the candidate source location (x,y,z) minus a distance between a location of the reference microphone and the candidate source location (x,y,z).14. The method of claim 13, wherein an integer index j is defined by a third algebraic expression j=0x1FF & int(k·D(r,m)), where int(k·D(r,m)) is a product k·D(r,m) rounded to a nearest integer, 0 x1FF is a hexadecimal representation of a decimal number 511, and & is a binary “and” function.15. The method of claim 14, wherein the phase delay eiθm is defined by a fourth algebraic expression eiθm=cos_table(j)+i·sin_table(j), where i is (?1)1/2, cos_table(j)=cos(π·j/256), and sin_table(j)=sin(π·j/256).16. The method of claim 9, wherein |S(k)|2 is defined by a fifth algebraic expression 17. The method of claim 9, wherein determining the location of the acoustic source further comprises the step of determining a maximum normalized total signal energy from the normalized total signal energies.18. An electronic-readable medium having embodied thereon a program, the program being executable by a machine to perform method steps for computing a location of an acoustic source, the method steps comprising:receiving acoustic signals from the acoustic source by an array of M-1 microphones and a reference microphone, each microphone identified by an integer microphone index m, 0?m?M-1; storing phase-delay look-up tables, the phase-delay look-up tables based upon a plurality of candidate source locations and a spatial configuration of the array of microphones; and processing the received acoustic signals using the phase-delay look-up tables to compute the location of the acoustic source. 19. The electronic-readable medium of claim 18, further comprising the steps of:processing each received acoustic signal to generate blocks of complex coefficients sampled in frequency, each complex coefficient of a block associated with a frequency bin number k, where 0?k?N-1; computing signal energies, a signal energy received by the array of microphones from a candidate source location of the plurality of candidate source locations for the frequency bin number k determined by multiplying a complex coefficient of a selected block from each received acoustic signal associated with a microphone m by an appropriate phase delay, summing the phase-delayed complex coefficients, and squaring the summation; and computing the location of the acoustic source by normalizing and summing the signal energies over the N frequency bin numbers for each candidate source location of the plurality of candidate source locations to give a total signal energy for each candidate source location. 20. The electronic-readable medium of claim 19, wherein the appropriate phase delay for the frequency bin number k, the candidate source location, and the microphone m is determined from a first phase-delay look-up table D(r,m), a second phase-delay look-up Table cos_table(j), and a third phase-delay look-up table sin_table(j), where r is a vector to the candidate source location of the plurality of candidate source locations and j is an integer computed from an algebraic expression based upon the first look-up table and the frequency bin number k.21. The electronic-readable medium of claim 19, wherein the computing the location of the acoustic source further comprises the step of determining a maximum total signal energy.22. A system for computing a location of an acoustic source, comprising:means for receiving acoustic signals from the acoustic source by an array of M-1 microphones and a reference microphone, each microphone identified by an integer microphone index m, 0?m?M-1; means for storing phase-delay look-up tables, the phase-delay look-up tables based upon a plurality of candidate source locations and a spatial configuration of the array of microphones; and means for processing the received acoustic signals using the phase-delay look-up tables to compute the location of the acoustic source.