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When working over a VoIP app, I struggle with Acoustic Echo Cancellation. I dumped the sounds - far-end, near-end and output. And the output is good, it doesn't contain echo. But when calling the Android smartphone produces this high pitch sound that drives me crazy, as soon as you increase the volume of its speakers.

I would like to know what is this sound and how to avoid/remove it?

high pitch sound

rightaway717
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  • It sounds like a feedback loop to me. If there's microphone at the source and the android phone speaker is too close, the mic will pick up the speaker output, transmit it VOIP and play it back out the speakers in a infinite loop of sorts. If this is the case try to acoustically isolate the devices from one another. Another possible source of feedback is in the AEC algorithm itself. – jaket Dec 12 '15 at 16:58
  • @jaket I test the AEC with devices in two separate closed rooms to isolate them. The output at the receiving device of this noise is clean after AEC and this high pitch sound is not sent back, so this high pitch sound is transmitted only one way, but heard on both sides as it is generated by Android phone and sent to/played by another side. – rightaway717 Dec 12 '15 at 17:23
  • @jaket, could you please answer, in case of feedback loop (in any Voip app when two phones are nearby and loudspeaker is used), is it possible to cancel it somehow? Or maybe just detect it so I could decrease volume to avoid this? I appreciate your help! – rightaway717 Dec 16 '15 at 14:00

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