99 Gs 300 - Humming In Dashboard

[sandiegoken]

My 1999 GS 300 has a hummimng noise that sounds like it is in the dash towards the middle- the noise is gets louder as I accelerate and is less noticable at higher speeds. One mechanic told me it was a heat shield of some type- but i am not sure. Has anyone else experienced this and have a solution?????

I recently took the radio out to replace the LED (another typical problem!) and looked around but didn't see anything that looked loose - and not sure why the noise would change with acceleration.