Acoustic feedback canceller

Abstract

In embodiments of this invention howling sounds are removed without disturbing speech and music. Microphone signals are converted to the frequency domain where howling frequencies are detected and estimated using howling to noise ratios. A notch filter adaptively designed for the howling frequency is applied to remove the howling.

Description

[0001] Cross References to Related Applications [0002] This application claims priority to US Provisional Application Serial No. 61 / 837,155, filed June 19, 2013, which is hereby incorporated by reference in its entirety. technical field [0003] The invention, in one embodiment, relates to controlling howling feedback in an audio signal. Background technique [0004] In public addressing (PA) or other audio systems, if the gain between one or more (speakers) and microphone(s) is greater than one and they are in phase, an annoying howling sound can occur . Typically, such howling can be eliminated by manually relocating the microphone and / or speaker. Alternatively, howling can be eliminated by using EQ filters to adjust the gain in different audio bands. However, these methods are inconvenient and / or impossible in some situations. For example, if the positions of the microphone and speaker are fixed and / or the EQ filter is not available, the above method cannot be used...

AI Technical Summary

Problems solved by technology

Although several prior art descriptions exist for digitally canceling howling, these prior art descriptions are deficient in one or more of the following aspects: the frequency of howling cannot be estimated accurately, especially when using a limited number of fast Fourier When transforming (FFT) points, howling is not effectively and reliably eliminated; tonal music signals are prone to false cancellation; the processed signal is distorted; or the processed signal is too complex to be implemented in an embedded system , thus consuming more funds or MIP than expected

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