T.V with built in freeview making weird noise

[Chrystal]

Hi,

A couple of days ago I bought a Dual DLCD1905 T.V, it has built in freeview.

I've been watching it tonight and I have noticed an annoying noise coming from the T.V. It's a high pitched noise, sounds a bit like crickets chirping at night...
On some stations it can be louder and on other stations barely there. The noise is still there if I mute the T.V.

The noise is only there when I am watching freeview channels, if I switch the T.V over to analogue the noise isn't there.

Any suggestions?

Thanks