'''++@zjdeere++'''
the only way to really determine what is going on and which piece of equipment is at fault, is by isolating it. Use a different input source for your TV. Try something like a DVD/BD player or even regular TV. Do not use your X-box for this just now. Either replace the HDMI cable or use a different port for it. Try different input ports like composite, component and even regular coax. Then see if the sound remains. Let us know what you find.