Also described at this link by a Reviewer:
http://www.fpslabs.com/reviews/headsets/turtle-beach-ear-force-ak-r8-review

This is nothing more than a good old FEEDBACK. The AA_SRM & AA-Amigo 
incorporate a built-in Microphone for convenience, in case there is no other 
Mic around. From the Windows mixer or the AA_SRM Control Panel, make sure 
that the Mic is Muted or the level turned down to avoid feedback. 
Feedback happens when a Microphone is in the line of 'sight' of the speakers.

See also: "Mic - Echoing problems - Feedback!"
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