Loudspeaker-to-microphone feedback causes echoes in audio/video conferences. A microphone typically has a background-noise level estimator, which provides noise-level estimates for the purpose of setting parameters within acoustic echo cancelers (AEC), noise reducers, comfort noise generators (CNG), etc. Output from a noisy loudspeaker may be picked up by the microphone, adding to background noise already present at the microphone. Loudspeaker noise, when picked up by the microphone, causes a misestimation of background noise, which in turn leads to incorrect parameter setting. This can lead to divergence of adaptive AEC circuitry, audible echoes, howling, etc.

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