Random Buzzing

[bumblebeemouth]

Hi,

I've had this problem since I bought my 2002 Avensis last year but its intermittent and I don't even know if its worth investigating. Every now and then I hear a buzz when I accelerate. I thought it was coming from the Speakers but you hear it in different places depending on where you are sitting in the car (yeah I know, you kinda have to be there!). The buzz also happens for a split second when my windscreen wipers reach the top of the window before coming back down. If this makes sense to anybody could you let me know what could be causing this problem??

Thanks in advance!!