Playback based on number of listeners

1. A playback device comprising:

one or more speakers;

at least one amplifier configured to drive the one or more speakers;

one or more location sensors comprising a network interface;

one or more processors comprising a digital signal processor; and

a housing carrying the one or more speakers, the at least one amplifier, the one or more location sensors, the one or more processors, and data storage for storing instructions that when executed cause the playback device perform functions comprising:

detecting, at a first time, a first number of listeners in a listening area, wherein detecting the first number of listeners comprises receiving, via the network interface of the one or more location sensors, network packets transmitted from a mobile device associated with a first listener, wherein the detected first number of listeners is one;

determining a first audio characteristic that adjusts a sound field generated by the one or more speakers to create a first sweet spot that includes a location of the first listener relative to the playback device;

processing, via the digital signal processor, an audio signal for playback according to the first audio characteristic;

playing the processed audio signal via the one or more speakers and the at least one amplifier according to the first audio characteristic;

while processing the audio signal for playback according to the first audio characteristic, detecting, at a second time, a second number of listeners in the listening area, wherein detecting the second number of listeners comprises receiving, via the network interface of the one or more location sensors, network packets transmitted from respective mobile devices associated with two or more second listeners, and wherein the detected second number of listeners is greater than one;

determining a second audio characteristic that adjusts the sound field generated by the one or more speakers to create a second sweet spot that includes respective locations of the two or more second listeners;

after determining the second audio characteristic, processing, via the digital signal processor, the audio signal for playback according to the second audio characteristic; and

playing the processed audio signal via the one or more speakers and the at least one amplifier according to the second audio characteristic.

2. The playback device of claim 1 , wherein the one or more location sensors further comprise an image capture device, wherein detecting the first number of listeners in the listening area comprises receiving image data representing the listening area at the first time, and wherein detecting the second number of listeners in the listening area comprises receiving image data representing the listening area at the second time.

3. The playback device of claim 1 , wherein the one or more location sensors further comprise a microphone, wherein detecting the first number of listeners in the listening area comprises receiving microphone data at the first time, and wherein detecting the second number of listeners in the listening area comprises receiving microphone data at the second time.

4. The playback device of claim 1 , wherein the first audio characteristic comprises a first audio filter, and wherein the second audio characteristic comprises a second audio filter.

5. The playback device of claim 1 , wherein the first audio characteristic comprises a first volume level, and wherein the second audio characteristic comprises a second volume level.

6. The playback device of claim 1 , wherein the playback device is a first playback device, and wherein the functions further comprise:

sending, via the network interface, an indication of the second number of listeners in the listening area to a second playback device, thereby causing the second playback device to adjust audio playback from the first audio characteristic to the second audio characteristic based on the detected second number of listeners in the listening area.

7. The playback device of claim 1 , wherein determining the second audio characteristic that adjusts the sound field generated by the one or more speakers to create the second sweet spot that includes respective locations of the two or more second listeners comprises determining a particular second audio characteristic that enlarges the first sweet spot to create the second sweet spot that includes respective locations of the two or more second listeners.

8. Tangible, non-transitory, computer-readable media having instructions encoded therein, wherein the instructions, when executed by one or more processors, cause a playback device to perform functions comprising:

detecting, at a first time, a first number of listeners in a listening area, wherein detecting the first number of listeners comprises receiving, via a network interface of one or more location sensors, network packets transmitted from a mobile device associated with a first listener, wherein the detected first number of listeners is one, and the playback device comprises a housing carrying the one or more location sensors;

determining a first audio characteristic that adjusts a sound field generated by one or more speakers of the playback device to create a first sweet spot that includes a location of the first listener relative to the playback device;

processing, via a digital signal processor of the playback device, an audio signal for playback according to the first audio characteristic, wherein the housing carries the digital signal processor;

while processing the audio signal for playback according to the first audio characteristic, detecting, at a second time, a second number of listeners in the listening area, wherein detecting the second number of listeners comprises receiving, via the network interface of the one or more location sensors, network packets transmitted from respective mobile devices associated with two or more second listeners, and wherein the detected second number of listeners is greater than one;

determining a second audio characteristic that adjusts the sound field generated by the one or more speakers to create a second sweet spot that includes respective locations of the two or more second listeners;

after determining the second audio characteristic, processing, via the digital signal processor, the audio signal for playback according to the second audio characteristic; and

playing the processed audio signal via one or more speakers and at least one amplifier according to the second audio characteristic, wherein the housing carries the one or more speakers and the at least one amplifier.

9. The tangible, non-transitory, computer-readable media of claim 8 , wherein the one or more location sensors further comprise an image capture device, wherein detecting the first number of listeners in the listening area comprises receiving image data representing the listening area at the first time, and wherein detecting the second number of listeners in the listening area comprises receiving image data representing the listening area at the second time.

10. The tangible, non-transitory, computer-readable media of claim 8 , wherein the first audio characteristic comprises a first audio filter, and wherein the second audio characteristic comprises a second audio filter.

11. The tangible, non-transitory, computer-readable media of claim 8 , wherein the first audio characteristic comprises a first volume level, and wherein the second audio characteristic comprises a second volume level.

12. The tangible, non-transitory, computer-readable media of claim 8 , wherein the playback device is a first playback device, the functions further comprising:

sending, via a network interface, an indication of the second number of listeners in the listening area to a second playback device, thereby causing the second playback device to adjust audio playback from the first audio characteristic to the second audio characteristic based on the detected second number of listeners in the listening area.

13. The tangible, non-transitory, computer-readable media of claim 8 , wherein the one or more location sensors further comprise a microphone, wherein detecting the first number of listeners in the listening area comprises receiving microphone data at the first time, and wherein detecting the second number of listeners in the listening area comprises receiving microphone data at the second time.

14. The tangible, non-transitory, computer-readable media of claim 8 , wherein determining the second audio characteristic that adjusts the sound field generated by the one or more speakers to create the second sweet spot that includes respective locations of the two or more second listeners comprises determining a particular second audio characteristic that enlarges the first sweet spot to create the second sweet spot that includes respective locations of the two or more second listeners.

15. A method to be performed by a playback device, the method comprising

detecting, at a first time, a first number of listeners in a listening area, wherein detecting the first number of listeners comprises receiving, via a network interface of one or more location sensors, network packets transmitted from a mobile device associated with a first listener, wherein the detected first number of listeners is one, and the playback device comprises a housing carrying the one or more location sensors;

determining a first audio characteristic that adjusts a sound field generated by one or more speakers to create a first sweet spot that includes a location of the first listener relative to the playback device;

processing, via a digital signal processor of the playback device, an audio signal for playback according to the first audio characteristic, wherein the housing carries the digital signal processor;

while processing the audio signal for playback according to the first audio characteristic, detecting, at a second time, a second number of listeners in the listening area, wherein detecting the second number of listeners comprises receiving, via the network interface of the one or more location sensors, network packets transmitted from respective mobile devices associated with two or more second listeners, and wherein the detected second number of listeners is greater than one;

determining, via the playback device, a second audio characteristic that adjusts the sound field generated by the one or more speakers to create a second sweet spot that includes respective locations of the two or more second listeners;

after determining the second audio characteristic, processing, via the digital signal processor of the playback device, the audio signal for playback according to the second audio characteristic; and

playing the processed audio signal via one or more speakers and at least one amplifier according to the second audio characteristic, wherein the housing carries the one or more speakers and the at least one amplifier.

16. The method of claim 15 , wherein the one or more location sensors further comprise a microphone, wherein detecting the first number of listeners in the listening area comprises receiving microphone data at the first time, and wherein detecting the second number of listeners in the listening area comprises receiving microphone data at the second time.

17. The method of claim 15 , wherein the first audio characteristic comprises a first audio filter, and wherein the second audio characteristic comprises a second audio filter.

18. The method of claim 15 , wherein the first audio characteristic comprises a first volume level, and wherein the second audio characteristic comprises a second volume level.

19. The method of claim 15 , wherein the playback device is a first playback device, and wherein the method further comprises:

sending, via the network interface, an indication of the second number of listeners in the listening area to a second playback device, thereby causing the second playback device to adjust audio playback from the first audio characteristic to the second audio characteristic based on the detected second number of listeners in the listening area.

20. The method of claim 15 , wherein determining the second audio characteristic that adjusts the sound field generated by the one or more speakers to create the second sweet spot that includes respective locations of the two or more second listeners comprises determining a particular second audio characteristic that enlarges the first sweet spot to create the second sweet spot that includes respective locations of the two or more second listeners.