High pitch whistle on acceleration

I have a '07 G6 GT that I inherited from my 87 y/o grandfather when he past away in January. Yes, it's red because what other color would an 87 year old man drive. Within the last 2 months I've started noticing a high pitch whistle/noise when I accelerate. If I back off the throttle its goes away. I thought it was brakes at first but I get no noise when I brake at any speed. Only when I accelerate. Anyone have any thoughts? Haven't brought it in yet, want to see if its a minor fix I can do myself.

Thanks.

Mario