fuzzy/white noise from monitor even when no sound is being played

[flashbourne]

i have my pc setup in dual monitors
the monitor with the problem is quite old and an american make (being used in the uk with an adaptor, 2 to 3 pin)
specific make: view sonic - nx2240w lcd tv
i previously used this for xbox gaming but changed it to a second monitor
when there is no sound coming you can hear a very noticeable fuzzy noise.
i have tried turning the volume down and up but makes no difference either way

i think it has always had this problem but i'm much more aware of it now that it is right next to me and it can get quite annoying.

does anybody have any idea what the problem might be? i thought it might have to do with the adapter and that i need to use a converter instead but want to make sure before dishing out £40 for one

thanks in advance.
if you need any more info that i may have missed i'll put it up

 

[hang-the-9]

I have a Vizio TV that does the same type of thing from the speakers when there is no audio or very low audio going through it, it's a known issue with my TV model. It may be due to the adapter or just how that TV is. Does the noise happen when there is no input cable to the audio in with it just being on, or from another source?