high pitched noise

When i crank up my psp i hear a reallly really high pitched noise coming from it, its not insanely loud but its when i'm charging it and i have never noticed it with another psp before.... is that bad?

and the noise only happens when the screen is on the lowest screen brightness, then the pitch gets softer on the 2nd highest, then it goes away on full brightness.... weird...

[crait]

Maybe it's got something to do with a short in the wire...
It could be extra energy is getting into the speakers from the screen, but whenever you use the screen at full brightness, the energy that would go to the speakers goes into the screen instead.