Back cavity microphone implementation

1. A system to perform signal processing using a loudspeaker acoustic output, the system comprising:

an enclosure configured to define a back cavity of the loudspeaker;

components configured to obtain an attenuated representation of the loudspeaker acoustic output at the back cavity, wherein the components include a port in the back cavity, a microphone having a first side arranged at the port in the back cavity, and a second port disposed on a second side of the microphone; and

a processor configured to process the attenuated representation to perform the signal processing.

2. The system according to claim 1 , wherein the loudspeaker is disposed in a handheld device.

3. The system according to claim 2 , wherein the processor is a digital signal processor of the handheld device.

4. The system according to claim 1 , wherein the enclosure is a box or a cylinder.

5. The system according to claim 1 , wherein the signal processing includes echo cancellation.

6. The system according to claim 1 , wherein the port in the back cavity is a hole in the enclosure.

7. The system according to claim 1 , wherein the components further include a diaphragm.

8. The system according to claim 7 , wherein the diaphragm is arranged inside the back cavity at an opening in the enclosure and the microphone is arranged on another side of the opening in communication with the diaphragm and is configured to respond to a motion of the diaphragm.

9. The system according to claim 1 , wherein the components include an accelerometer arranged on a portion of the enclosure outside the back cavity.

10. A method of performing signal processing of a loudspeaker acoustic output of a device, the method comprising:

enclosing the loudspeaker in an enclosure configured to define a back cavity of the loudspeaker;

obtaining an attenuated representation of the loudspeaker acoustic output in the back cavity;

processing the attenuated representation of the loudspeaker acoustic output using a processor to perform the signal processing;

disposing a port in the back cavity;

arranging a first side of a microphone at the port in the back cavity;

obtaining the attenuated representation of the loudspeaker acoustic output using the microphone; and

disposing a second port on a second side of the microphone.

11. The method according to claim 10 , wherein the enclosing the loudspeaker includes defining the back cavity using a box or a cylinder.

12. The method according to claim 10 , wherein the processing includes performing echo cancellation.

13. The method according to claim 10 , wherein the disposing the port in the back cavity includes creating an opening in the back cavity.

14. The method according to claim 10 , further comprising disposing a diaphragm in the back cavity at an opening in the back cavity, disposing the microphone outside of the back cavity, and obtaining the attenuated representation of the loudspeaker acoustic output based on the microphone responding to a motion of the diaphragm.

15. The method according to claim 10 , further comprising disposing an accelerometer on an outside of a back cavity wall and obtaining the attenuated representation of the loudspeaker acoustic output from the accelerometer.

16. The method according to claim 15 , further comprising adjusting a shape and thickness of the back cavity wall to control an amplitude of a signal from the accelerometer.