2008 Audi A4 1.8T , intermittent and constant high pitched noise while radio is playing its not linked to the revs of vehicle and also occurs while engine is of... while high pitched noise is happening if i increase the volume the squealing increases also and visa versa.. it could not squeal for 5mins then squeal constant for 5 or shorter period, there is no pattern to pin point issue, just annoying and unpleasant that radio is not able to be used due to this issue. Any help would be appreciated. Thanks