Method and apparatus for identifying feedback in a circuit

An electronic circuit for identifying feedback in an audio signal, the electronic circuit comprising:

• a feedback control block operable to determine a candidate frequency having potential feedback,
• the candidate frequency determined by a three-layered, narrowing band iterative process whereby a determined frequency corresponding to a maximum magnitude in a first frequency band at a first iteration becomes a center frequency for a frequency band of a second iteration and a determined frequency corresponding to a maximum magnitude in a second frequency band becomes a center frequency for a frequency band of a third iteration, the feedback control block further operable to perform an iterative analysis of the magnitude of the audio signal at the candidate frequency to determine the growth characteristics of the signal, such that after a first magnitude determination at a first instance in time, the magnitude of the audio signal is greater at a second instance in time;
• a test filter block operable to deploy a test filter at a candidate frequency;
• and
• a permanent filter block operable to deploy a permanent filter at the candidate frequency if the feedback control block determines that the growth characteristics of the signal at the candidate frequency are eliminated after the test filter has been deployed such that at a third instance in time after the first and second instances in time, the magnitude of the audio signal is not greater.

A system for controlling feedback in audio signals, the system comprising:

• a pre-amplifier operable to amplify a weak analog audio signal;
• an analog-to-digital converter coupled to the preamplifier and operable to convert the pre-amplified analog audio signal into a digital audio signal;
• a feedback suppression circuit coupled to the analog-to-digital converter, the feedback suppression circuit including:
• a feedback control block operable to determine a candidate frequency having potential feedback, the candidate frequency determined by a three-layered, narrowing band iterative process whereby a determined frequency corresponding to a maximum magnitude in a first frequency band at a first iteration becomes a center frequency for a frequency band of a second iteration and a determined frequency corresponding to a maximum magnitude in a second frequency band becomes a center frequency for a frequency band of a third iteration, the feedback control block further operable to perform an iterative analysis of the magnitude of the audio signal at the candidate frequency to determine the growth characteristics of the signal, such that after a first magnitude determination at a first instance in time, the magnitude of the audio signal is greater at a second instance in time;
• a test filter block operable to deploy a test filter at a candidate frequency;
• and
• a permanent filter block operable to deploy a permanent filter at the candidate frequency if the feedback control block determines that the growth characteristics of the signal at the candidate frequency are eliminated after the test filter has been deployed such that at a third instance in time after the first and second instances in time, the magnitude of the audio signal is not greater;
• a digital-to-analog converter coupled to the feedback suppression circuit and operable to convert the digital audio signal into an analog audio signal;
• and
• an amplifier coupled to the digital-to-analog signal converter and operable to amplify the analog audio signal.