Audio signal processor and method therefor for substantially reducing audio feedback in a cummunication unit

An audio signal processor for substantially reducing audio feedback in a communication unit, comprising:

• a forward signal path having a forward audio signal coupled to a loudspeaker for producing a first acoustic signal;
• a reverse signal path coupled to a microphone for producing a reverse audio signal, wherein at least a portion of the first acoustic signal is coupled to the microphone for producing a feedback audio signal on the reverse signal path;
• a signal estimator for providing a signal estimate of the feedback audio signal;
• a noise estimator for providing a noise estimate of the feedback audio signal;
• and
• an attenuator, coupled to the microphone, for attenuating the reverse audio signal responsive to a measure of the signal estimate and the noise estimate of the feedback audio signal.

An audio signal processor for substantially reducing audio feedback in a communication unit, comprising:

• a reverse signal path coupled to a microphone for producing a reverse audio signal;
• a forward signal path having a forward audio signal coupled to a loudspeaker, wherein at least a portion of the reverse audio signal is coupled to the forward signal path to produce a feedback audio signal on the forward signal path;
• a signal estimator for providing a signal estimate of the feedback audio signal;
• a noise estimator for providing a noise estimate of the feedback audio signal;
• and
• an attenuator, coupled to the loudspeaker, for attenuating the forward audio signal responsive to a measure of the signal estimate and the noise estimate of the feedback audio signal.

An audio signal processor for substantially reducing audio feedback in a communication unit, comprising:

• a first signal path having a first attenuator coupled to a loudspeaker and a first audio signal coupled to the loudspeaker for producing a first acoustic signal;
• a second signal path coupled to a microphone, coupled to a second attenuator, for producing a second audio signal, wherein at least a portion of the first acoustic signal is coupled to the microphone to produce a feedback audio signal on the second signal path;
• an echo canceller coupled to receive the first audio signal, the second audio signal and an error signal, and operative to produce an estimate of the second audio signal and an echo return loss signal;
• a first signal processor for measuring the level of the first audio signal to produce a first measured signal;
• a first signal level detector for detecting the presence of the first audio signal to produce a first detected signal responsive to the first measured signal, wherein the first detected signal is coupled to the first and the second attenuators;
• a second signal processor for measuring the level of the second audio signal to produce a second measured signal;
• a second signal level detector for detecting the presence of the second audio signal to produce a second detected signal responsive to the first and second measured signals and the echo return loss signal;
• a signal estimator for providing a signal estimate of the feedback audio signal;
• a noise estimator for providing a noise estimate of the feedback audio signal;
• and
• an attenuation controller for controlling the second attenuator responsive to a measure of the signal estimate and the noise estimate of the feedback audio signal.

In an audio signal processor including a first signal path having a first audio signal and a second signal path having a second audio signal, wherein at least a portion of the first audio signal is coupled to the second signal path to produce a feedback audio signal on the second signal path, a method for substantially reducing audio feedback in a communication unit, comprising the steps of:

• measuring a signal estimate and a noise estimate of the feedback audio signal;
• and
• attenuating the second audio signal responsive to the measure of the signal estimate;
• and the noise estimate of the feedback audio signal.

In an audio signal processor including a first signal path having a first attenuator coupled to a loudspeaker and a first audio signal coupled to the loudspeaker for producing a first acoustic signal, a second signal path coupled to a microphone, coupled to a second attenuator, for producing a second audio signal, wherein at least a portion of the first acoustic signal is coupled to the microphone to produce a feedback audio signal on the second signal path, and an echo canceller coupled to receive the first audio signal, the second audio signal and an error signal, and operative to produce an estimate of the second audio signal and an echo return loss signal, a method for substantially reducing audio feedback in a communication unit, comprising the steps of:

• measuring the level of the first audio signal to produce a first measured signal;
• detecting the presence of the first audio signal to produce a first detected signal responsive to the first measured signal, wherein the first detected signal is coupled to the first and the second attenuators;
• measuring the level of the second audio signal to produce a second measured signal;
• detecting the presence of the second audio signal to produce a second detected signal responsive to the first and second measured signals and the echo return loss signal;
• measuring a signal estimate and a noise estimate of the feedback audio signal;
• and
• controlling the attenuation of the second audio signal responsive to a measure of the signal estimate and the noise estimate of the feedback audio signal.