speaker noise?

Noted as o4 T&C but really 05. I notice a high pitch whine when cruising as I press on gas. All windows are closed so not from outside. Letting off gas drops whine to almost inaudible. Radio off or on at very low volume - no difference. Maybe coming from speakers through plugs or alternator? Is there something I can do? Will a choke fix this - where? Really distracting.