Acoustic echo cancellation reference signal
Systems and methods for acoustic echo cancellation are provided. An example method includes receiving a reference signal. The reference signal represents at least one sound captured inside an enclosure of a loudspeaker. The loudspeaker is operable to play back a far end signal. The method also includes receiving an acoustic signal. The acoustic signal represents at least one sound captured outside the enclosure of the loudspeaker. The acoustic signal includes at least a near end signal and the far end signal. The method enables attenuation, using the reference signal, the far end signal in the acoustic signal. The reference signal can be captured by a low sensitivity microphone placed inside the enclosure of the loudspeaker. The attenuation of the far end signal may include subtractive cancellation.
1. A method for acoustic echo cancellation, the method comprising:
receiving a reference signal representing at least sound produced by a loudspeaker, the reference signal being generated while the loudspeaker is being operated to play back a far end signal;
receiving an electrical acoustic signal, the electrical acoustic signal including a near end component representing captured sound and a far end component representing the far end signal played by the loudspeaker; and
attenuating, using the reference signal, the far end component in the electrical acoustic signal,
wherein the reference signal is produced by a microphone placed inside an enclosure of the loudspeaker,
and wherein the dimensions of the enclosure are considerably smaller than sound waves.
2. The method of claim 1 , wherein the reference signal is produced by a low sensitivity microphone that is positioned to receive the sound produced by the loudspeaker.
3. The method of claim 1 , wherein the attenuation of the far end component includes:
filtering the reference signal to obtain a filtered version of the reference signal; and
performing subtractive cancellation using the filtered version of the reference signal.
4. The method of claim 1 , wherein the reference signal includes nonlinear effects introduced by the loudspeaker when the loudspeaker plays back the far end signal.
5. A device for acoustic echo cancellation, the device comprising:
a summing element having a first input for receiving a reference signal representing at least sound produced by a loudspeaker, the reference signal being generated while the loudspeaker is being operated to play back a far end signal, the summing element having a second input for receiving an electrical acoustic signal including a near end component representing captured sound and a far end component representing the far end signal played back by the loudspeaker,
wherein the summing element is adapted to attenuate, using the reference signal, the far end component in the electrical acoustic signal,
wherein the reference signal is produced by a microphone placed inside an enclosure of the loudspeaker,
and wherein the dimensions of the enclosure are considerably smaller than sound waves.
6. The device of claim 5 , wherein the reference signal is produced by a low sensitivity microphone that is positioned to receive the sound produced by the loudspeaker.
7. The device of claim 5 , wherein the attenuation of the far end component includes:
filtering the reference signal to obtain a filtered version of the reference signal; and
performing subtractive cancellation using the filtered version of the reference signal.
8. The device of claim 5 , wherein the reference signal includes nonlinear effects introduced by the loudspeaker when the loudspeaker plays back the far end signal.
9. A device comprising:
a loudspeaker being operable to play back a far end signal;
a first microphone for producing a reference signal representing at least sound captured from the loudspeaker;
a second microphone for producing an electrical acoustic signal, the electrical acoustic signal representing a near end component representing captured sound, the electrical acoustic signal further including a far end component representing the far end signal played by the loudspeaker; and
an acoustic echo canceller adapted to attenuate, using the reference signal, the far end component in the electrical acoustic signal,
wherein the first microphone is placed inside an enclosure of the loudspeaker,
and wherein the dimensions of the enclosure are considerably smaller than sound waves.
10. The device of claim 9 , wherein the first microphone comprises a low sensitivity microphone.
11. The device of claim 9 , wherein the enclosure comprises a base reflex system with a vent.
12. The device of claim 9 , wherein the loudspeaker and the first microphone are completely sealed within the enclosure.
13. The device of claim 9 , wherein the loudspeaker comprises a passive radiator loudspeaker.
14. The device of claim 9 , wherein the device comprises a cellular phone.
15. The device of claim 9 , wherein the device comprises a phone headset.
16. The device of claim 9 , wherein the device comprises a conferencing system.