Multi-speaker method and apparatus for leakage cancellation
Embodiments of systems and methods are described for reducing undesired leakage energy produced by a non-front-facing speaker in a multi-speaker system. For example, the multi-speaker system can include an array of forward-facing speakers, one or more upward-facing speakers, and/or one or more side-facing speakers. Filters coupled to any two of the speakers in the multi-speaker system can generate audio signals output by the coupled speakers to reduce, attenuate, or cancel a portion of an audio signal output by one or more non-front-facing speakers that acoustically propagates along a direct path from the respective non-front-facing speaker to a listening position in a listening area in front of the multi-speaker system.
1. A speaker system comprising:
a first speaker;
a microphone;
a processor configured to:
instruct the first speaker to output a test audio signal;
obtain a measurement captured by the microphone that corresponds to the outputted tested audio signal;
determine a transfer function using a portion of the measurement that does not include reflections and using the test audio signal;
determine a filter coefficient using the transfer function; and
cause a filter to use the filter coefficient to generate a second audio signal that attenuates an input audio signal acoustically propagated by the first speaker to a listening area via a direct path.
2. The speaker system of claim 1 , wherein the processor is further configured to
process the measurement to remove the reflections to create the portion of the measurement that does not include reflections.
3. The speaker system of claim 1 , wherein the processor is further configured to:
generate a plurality of weights using the transfer function; and
combine the plurality of weights to form the filter coefficient.
4. The speaker system of claim 3 , wherein each weight in the plurality of weights is associated with one of a frequency or frequency range.
5. The speaker system of claim 3 , wherein the processor is further configured to combine the plurality of weights by calculating an inverse discrete Fourier transform.
6. The speaker system of claim 1 , wherein a delay component is positioned in a path between a source of the input audio signal and the first speaker.
7. The speaker system of claim 1 , wherein the processor is comprised within a soundbar, and wherein the processor is further configured to store the filter coefficient in memory of the soundbar.
8. The speaker system of claim 7 , wherein the processor is further configured to store the filter coefficient in the memory in association with one of an orientation of the first speaker, playback room characteristics, or speaker setup geometries.
9. The speaker system of claim 1 , wherein the first speaker is one of a side-facing speaker or an upward-facing speaker.
10. The speaker system of claim 1 , wherein the second audio signal, when output by a second speaker, attenuates the input audio signal acoustically propagated by the first speaker to the listening area via the direct path to increase audibility of an input audio signal acoustically propagated by the first speaker to the listening area via an indirect path.
11. The speaker system of claim 1 , wherein the speaker system comprises one of a soundbar, an audio/visual (A/V) receiver, a center speaker, or a television.
12. A method for attenuating undesired leakage energy from a first speaker, the method comprising:
instructing the first speaker to output a test audio signal;
obtaining a measurement corresponding to the outputted test audio signal;
determining a transfer function using a portion of the measurement that does not include reflections and using the test audio signal;
determining a filter coefficient using the transfer function; and
causing a filter to use the filter coefficient to generate a second audio signal that attenuates an input audio signal acoustically propagated by the first speaker to a listening area via a direct path.
13. The method of claim 12 , wherein determining a transfer function further comprises:
truncating the measurement to remove the reflections to create the portion of the measurement that does not include reflections; and
determining the transfer function using the truncated measurement and the test audio signal.
14. The method of claim 12 , wherein determining a filter coefficient further comprises:
generating a plurality of weights using the transfer function; and
combining the plurality of weights to form the filter coefficient.
15. The method of claim 14 , wherein each weight in the plurality of weights is associated with one of a frequency or frequency range.
16. The method of claim 12 , wherein the first speaker is one of a side-facing speaker or an upward-facing speaker.
17. The method of claim 12 , wherein the second audio signal, when output by a second speaker, attenuates the input audio signal acoustically propagated by the first speaker to the listening area via the direct path paths such that an input audio signal acoustically propagated by the first speaker to the listening area via an indirect path is more audible than the input audio signal acoustically propagated by the first speaker to the listening area via the direct path.
18. A speaker system comprising:
a plurality of first speakers;
a processor configured to:
instruct each of the plurality of first speakers to output a first audio signal;
obtain a plurality of measurements that each correspond to one of the outputted first audio signals;
determine a response generated by at least the plurality of first speakers using a portion of the plurality of measurements that does not include reflections, wherein the response is associated with a listening area;
determine a filter coefficient based on the response; and
cause a filter to use the filter coefficient to generate a second audio signal that attenuates an input audio signal acoustically propagated by at least one of the plurality of first speakers to the listening area via a direct path.
19. The system of claim 18 , wherein each of the plurality of first speakers is one of a side-facing speaker or an upward-facing speaker.
20. The system of claim 18 , wherein the first audio signals are one of a test sequence output simultaneously by the plurality of first speakers or nominal audio content output by the plurality of first speakers.
21. The system of claim 18 , wherein the response comprises a sound pressure.