Wearable audio device with feedback instability control

1. A method of controlling feedback instability in a wearable audio device with an active noise reduction (ANR) system, the method comprising:

determining a current feedback instability by combining outputs from multiple instability detectors,

applying latch logic to the current feedback instability to determine a current mitigation value,

wherein applying the latch logic comprises:

applying a baseline mitigation value associated with a baseline instability as the current mitigation value, and

modifying the current mitigation value in response to determining that the current feedback instability exceeds the baseline instability as controlled by a latch mechanism; and

adjusting a driver command signal based on the current mitigation value to mitigate feedback instability, wherein the baseline mitigation value is a lowest available multiplier that can be applied to the driver command signal.

2. The method of claim 1 , wherein the baseline mitigation value is a single value that is greater than zero and no greater than one.

3. The method of claim 1 , wherein applying the baseline mitigation value is performed after detecting the baseline instability value exceeds a nominal instability value associated with a nominal instability mitigation value.

4. The method of claim 3 , wherein the nominal instability value is associated with a startup operation, a restart operation, or a mode change of the ANR system.

5. The method of claim 1 , further comprising feeding the current mitigation value into an integrator to control a baseline mitigation value.

6. The method of claim 5 , wherein feeding the current mitigation value into the integrator in controlling the baseline mitigation value smooths a transition between outputs from the ANR system.

7. The method of claim 5 , wherein the current mitigation value is summed with the current feedback instability at the integrator.

8. The method of claim 7 , further comprising feeding the summed current mitigation value and current feedback instability value back through the latch logic.

9. The method of claim 7 , wherein the current mitigation value is continuously updated based on changes in the current feedback instability.

10. The method of claim 7 , wherein the current mitigation value is greater than zero and no greater than one, and wherein the current mitigation value is incrementally adjustable.

11. A wearable audio device comprising:

an electro-acoustic transducer for providing an audio output,

at least one microphone configured to detect noise; and

a controller coupled with the electro-acoustic transducer and the at least one microphone, the controller including an active noise reduction (ANR) system for controlling noise in the audio output, wherein the controller is configured to:

determine a current feedback instability by combining outputs from multiple instability detectors,

apply latch logic to the current feedback instability to determine a current mitigation value, wherein applying the latch logic comprises:

applying a baseline mitigation value associated with a baseline instability as the current mitigation value, after detecting the baseline instability value exceeds a nominal instability value associated with a nominal instability mitigation value, and

modifying the current mitigation value in response to determining that the current feedback instability exceeds the baseline instability as controlled by a latch mechanism, and

adjust a driver command signal based on the current mitigation value to mitigate feedback instability.

12. The wearable audio device of claim 11 , wherein the baseline mitigation value is a single value that is greater than zero and no greater than one.

13. The wearable audio device of claim 11 , wherein the nominal value is associated with a startup operation, a restart operation, or a mode change of the ANR system.

14. The wearable audio device of claim 11 , wherein the baseline mitigation value is a lowest available multiplier that can be applied to the driver command signal.

15. The wearable audio device of claim 11 , wherein the controller is further configured to determine an instability error value for the ANR system based on a comparison of the current instability value to a setpoint instability value, and, apply a gain to the instability error value.

16. The wearable audio device of claim 11 , wherein adjusting the driver command signal based on the current mitigation value smooths a transition between ANR settings.

17. The wearable audio device of claim 11 , wherein the controller is further configured to feed the current mitigation value into an integrator to control a baseline mitigation value.

18. A wearable audio device comprising:

an electro-acoustic transducer for providing an audio output,

at least one microphone configured to detect noise; and

a controller coupled with the electro-acoustic transducer and the at least one microphone, the controller including an active noise reduction (ANR) system for controlling noise in the audio output, wherein the controller is configured to:

determine a current feedback instability by combining outputs from multiple instability detectors,

apply latch logic to the current feedback instability to determine a current mitigation value,

feed the current mitigation value into an integrator to control a baseline mitigation value, and

adjust a driver command signal based on the current mitigation value to mitigate feedback instability.

19. The wearable audio device of claim 18 , wherein the baseline mitigation value is a single value that is greater than zero and no greater than one.

20. The wearable audio device of claim 18 , wherein the baseline mitigation value is a lowest available multiplier that can be applied to the driver command signal.