Hi dick66.
Welcome to the Heartland Owners forum and family. We have a great bunch of people here with lots of information and all willing to share if needed.
I have never heard of and electrical outlet making any noise at all,,, but you need to check in the area for your smoke detector or others that may be near... I don't hear high pitch sounds very good myself and sometimes when one goes off from cooking, it sounds like it is coming from someplace else.. I don't know about a GFI plug that may be there,, but always a possibility.
Let us know what you find.
Enjoy the forum.
Jim M