Systems and methods for using a speaker as a microphone
In accordance with methods and systems of the present disclosure, a mobile device may include an enclosure adapted such that the enclosure is readily transported by a user of the mobile device, a speaker associated with the enclosure for generating sound, and a controller within the enclosure, communicatively coupled to the speaker. The controller may be configured to receive a signal from the speaker, the signal induced at least in part by sound incident on the speaker other than sound generated by the speaker and process the signal.
1. A method comprising:
receiving a first signal from a speaker, the first signal induced at least in part by sound incident on the speaker other than sound generated by the speaker;
receiving a second signal from a microphone, the second signal induced by sound incident on the microphone; and
processing at least one of the first signal and the second signal to determine at least one characteristic of sound incident upon at least one of the speaker and the microphone; and
selecting one of the microphone and the speaker as a signal source for incident sound based on the characteristic.
2. The method of claim 1 , wherein the first signal is a voltage signal.
3. The method of claim 1 , further comprising:
operating the speaker in a first mode wherein a controller within the enclosure communicates an output signal to the speaker for generating sound; and
operating the speaker in a second mode wherein the controller deactivates the speaker from emitting sound and receives the first signal induced by sound incident on the speaker other than sound generated by the speaker and processes the first signal.
4. The method of claim 1 , further comprising transitioning a device comprising the speaker from a low-power state to a high-power state responsive to a determination that the first signal induced by sound incident on the speaker corresponds to stimulus for transitioning the device from a low-power state to a high-power state.
5. The method of claim 1 , further comprising performing frequency equalization on the first signal and the second signal in order to account for differences in the frequency responses to sound incident upon the speaker and the microphone, wherein performing frequency equalization on the first signal and the second signal comprises applying adaptive filtering during periods of time in which both the microphone is communicating the second signal to the controller and the speaker is communicating the first signal to the controller.
6. The method of claim 1 , wherein the at least one characteristic comprises at least one of: (i) a volume level of sound incident on at least one of the speaker and the microphone; and (ii) a frequency of sound incident on at least one of the speaker and the microphone.
7. The method of claim 1 , wherein processing the first signal comprises:
determining a magnitude of the first signal; and
subtracting a magnitude of a second signal from the magnitude of the first signal, the second signal communicated to the speaker for generating sound at the speaker, such that a difference between the magnitude of the first signal and the magnitude of the second signal is approximately equal to a portion of the first signal attributable to sound incident on the speaker other than sound generated by the speaker.
8. The method of claim 1 , further comprising:
based on sound incident at the speaker and sound incident on the microphone, performing beamforming to determine spatial selectivity of sounds incident on the speaker and the microphone.
9. The method of claim 1 , wherein the speaker is a dynamic speaker.
10. The method of claim 1 , wherein the microphone is a capacitive microphone.
11. An integrated circuit comprising: a first input configured to receive a first signal from a first speaker, the first signal induced at least in part by sound incident on the first speaker other than sound generated by the first speaker; a second input configured to receive a second signal from a second speaker, the second signal induced at least in part by sound incident on the second speaker other than sound generated by the second speaker; and a processing circuit configured to: process at least one of the first signal and the second signal to determine at least one characteristic of sound incident on at least one of the first speaker and the second speaker; select one of the first speaker and the second speaker as a signal source for incident sound based on the at least one characteristic; and select the other one of the first speaker and the second speaker to generate sound based on the at least one characteristic.
12. The integrated circuit of claim 11 , wherein the at least one characteristic comprises at least one of a volume level of sound incident on at least one of the first speaker and the second speaker and a frequency of sound incident on at least one of the first speaker and the second speaker.
13. A method comprising:
receiving a first signal from a first speaker, the first signal induced at least in part by sound incident on the first speaker other than sound generated by the first speaker;
receiving a second signal from a second speaker, the second signal induced at least in part by sound incident on the second speaker other than sound generated by the second speaker;
processing at least one of the first signal and the second signal to determine at least one characteristic of sound incident on at least one of the first speaker and the second speaker;
selecting one of the first speaker and the second speaker as a signal source for incident sound based on the at least one characteristic; and
selecting the other one of the first speaker and the second speaker to generate sound based on the at least one characteristic.
14. The method of claim 13 , wherein the at least one characteristic comprises at least one of a volume level of sound incident on at least one of the first speaker and the second speaker and a frequency of sound incident on at least one of the first speaker and the second speaker.