High pitched noise..help
 

Hello everyone. Finally got my first 5.0 mustang and I love it. It's a 2011 gt/cs. I've had it for about a month and I've noticed a very annoying noise. It's very high pitched almost like an ear ringing noise and its coming from somewhere in the dash. It's very hard to pin point. It wasn't always there. Its driving me nuts. Any idea what It can be? Or what i can look for? Thanks.