Patent ID: 7068797

Claim:
A method of operating a microphone circuit, comprising: generating a first microphone signal via a first microphone, the first microphone signal including a contribution associated with an output signal that is generated by a loudspeaker in response to an input signal; generating a second microphone signal via a second microphone, the second microphone signal including a contribution associated with the output signal from the loudspeaker; delaying the second microphone signal by a delay value; combining the delayed second microphone signal with the first microphone signal to provide a combined microphone signal; and adjusting the delay value based on the input signal to the loudspeaker and the combined microphone signal so as to reduce at least a portion of the contribution to the combined microphone signal associated with the output signal from the loudspeaker, wherein adjusting the delay value comprises: removing at least a portion of the input signal to the loudspeaker from the combined microphone signal to provide a difference signal; and adjusting the delay value based on the difference signal.