Method and system for determining a direction between a detection point and an acoustic source
View Patent ↗A method including: receiving acoustic signals originating from an acoustic source at a first pair of microphone elements, arranged symmetrically about a detection point; calculating, with a processor device, a cross correlation of signals provided by the first pair of microphone elements, resulting in a first cross correlation signal; receiving the acoustic signals originating from the acoustic source at a second pair of microphone elements, arranged symmetrically about the detection point; calculating, with the processor device, a cross correlation of signals provided by the second pair of microphone elements, resulting in a second cross correlation signal; and calculating, with the processor device, a direction between the detection point and the acoustic source based on a convolution of the first cross correlation signal by the second cross correlation signal.
1. A method comprising:
receiving acoustic signals originating from an acoustic source at a first pair of microphone elements, arranged symmetrically about a detection point;
calculating, with a processor device, a cross correlation of signals provided by the first pair of microphone elements, resulting in a first cross correlation signal;
receiving the acoustic signals originating from the acoustic source at a second pair of microphone elements, arranged symmetrically about the detection point;
calculating, with the processor device, a cross correlation of signals provided by the second pair of microphone elements, resulting in a second cross correlation signal; and
calculating, with the processor device, a direction between the detection point and the acoustic source based on a convolution of the first cross correlation signal by the second cross correlation signal.
2. The method according to claim 1 , wherein the convolving the first cross correlation signal by the second cross correlation signal is performed in a frequency domain.
3. The method according to claim 1 , wherein the calculating the direction between the detection point and the acoustic source comprises:
identifying a maximum point of the result of the convolving.
4. The method according to claim 3 , further comprising:
calculating an angle of incidence, representing the direction between the detection point and the acoustic source, based on the maximum point.
5. The method according to claim 1 , wherein the first and second pairs of microphone elements are arranged in a linear microphone array located at the detection point, and the microphone elements are located symmetrically about an axis of incidence passing through the detection point.
6. The method according to claim 5 , wherein the first pair of microphone elements is an inner pair of microphone elements, and the second pair of microphone elements is an outer pair of microphone elements.
7. The method according to claim 1 , further comprising:
receiving the acoustic signals originating from the acoustic source at an M-th pair of microphone elements, arranged symmetrically about the detection point;
calculating a cross correlation of signals provided by the M-th pair of microphone elements, resulting in an M-th cross correlation signal; and
wherein the calculating the direction between the detection point and the acoustic source is based on the M-th cross correlation signal, and M is an integer greater than 2.
8. The method according to claim 1 , wherein the acoustic source is an active participant in a video conference, and the detection point coincides with a location of a variable-direction video camera in a video conference equipment, and the method further comprises:
controlling the camera to point in a direction of the acoustic source.
9. A system comprising:
a processor device;
a first pair of microphone elements, arranged symmetrically about a detection point, that receive acoustic signals originating from an acoustic source;
a first cross correlator configured to calculate, with the processor device, a cross correlation of signals provided by the first pair of microphone elements, resulting in a first cross correlation signal;
a second pair of microphone elements, arranged symmetrically about the detection point, that receive acoustic signals originating from the acoustic source;
a second cross correlator configured to calculate, with the processor device, a cross correlation of signals provided by the second pair of microphone elements, resulting in a second cross correlation signal;
a convolver configured to calculate a first convolution of convolving the first cross correlation signal with the second cross correlation signal; and
a direction calculator configured to calculate, with the processor device, a direction between the detection point and the acoustic source based on the first convolution of convolving the first cross correlation signal by the second cross correlation signal.
10. The system according to claim 9 , wherein the convolver is configured to convolve the first cross correlation signal by the second cross correlation signal in a frequency domain.
11. The system according to claim 9 , wherein the direction calculator is configured to calculate the direction between the detection point and the acoustic source by identifying a maximum point of the output of the convolver.
12. The system according to claim 11 , wherein the direction calculator is configured to calculate an angle of incidence, representing the direction between the detection point and the acoustic source, based on the maximum point.
13. The system according to claim 9 , wherein the first and second pairs of microphone elements are arranged in a linear microphone array located at the detection point, and the microphone elements are located symmetrically about an axis of incidence passing through the detection point.
14. The system according to claim 13 , wherein the first pair of microphone elements is an inner pair of microphone elements, and the second pair of microphone elements is an outer pair of microphone elements.
15. The system according to claim 9 , further comprising:
an M-th pair of microphone elements, arranged symmetrically about the detection point, that receive the acoustic signals originating from the acoustic source;
an M-th cross correlator, configured to calculate a cross correlation of signals provided by the M-th pair of microphone elements, resulting in an M-th cross correlation signal; and
an arrangement of convolvers,
wherein the direction calculator and the arrangement of convolvers are configured to calculate the direction between the detection point and the acoustic source based also on the M-th cross correlation, and M is an integer greater than 2.
16. The system according to claim 9 , wherein:
the acoustic source is an active participant in a video conference, and the detection point coincides with a location of a variable-direction video camera in a video conference equipment, and
the system further comprises a camera controller configured to control the camera to point in a direction of the acoustic source.
17. A non-transitory computer readable storage medium encoded with instructions, which when executed by a processor causes the processor to execute a method comprising:
receiving acoustic signals originating from an acoustic source at a first pair of microphone elements, arranged symmetrically about a detection point;
calculating a cross correlation of signals provided by the first pair of microphone elements, resulting in a first cross correlation signal;
receiving the acoustic signals originating from the acoustic source at a second pair of microphone elements, arranged symmetrically about the detection point;
calculating a cross correlation of signals provided by the second pair of microphone elements, resulting in a second cross correlation signal; and
calculating a direction between the detection point and the acoustic source based on a convolution of the first cross correlation signal by the second cross correlation signal.
18. The system according to claim 14 , wherein a distance between the axis of incidence and each of the first pair of microphone elements is different from a distance between each of the second pair of microphone elements and a closest one of the first pair of microphone elements.
19. The system according to claim 13 , further comprising:
a third pair of microphone elements, arranged symmetrically about the detection point, that receive acoustic signals originating from the acoustic source, wherein
the first, second, and third pair of microphone elements are respectively provided at first, second, and third distances away from the detection point, where the first distance is less than the second distance, and the second distance is less than the third distance.
20. The system according to claim 19 , further comprising:
a third cross correlator configured to calculate, with the processor device, a cross correlation of signals provided by the third pair of microphone elements, resulting in a third cross correlation signal; and
a second convolver configured to calculate a second convolution of convolving the third cross correlation signal with the first convolution, wherein
the direction calculator is configured to calculate, with the processor device, the direction between the detection point and the acoustic source based on the second convolution.