Issue with FaceTime 1.5 on 2009 iMac.

When hen I use FaceTime using the built in mic on my iMac, the people I talk to hear a buzzing noise that they say is coming from my end of the FaceTime connection, and they have a hard time hearing me. Reception on my iMac is fine with no buzzing noises.

I do not hear anything around my immediate Mac's environment that would be causing this buzzing noise being present on the other end of the FaceTime connection.

Anyone have any ideas about why this could be happening?

FaceTiming from my iPad causes NO issues or buzzing noises at the receiving end of a FaceTime call.