How can I tell if a humming sound is coming from something electrical(in the wall)or my head?

i have been hearing a humming sound and sometimes it gets louder but i cant tell if its coming from something in the wall (perhaps faulty wiring in the wall that is a low tone but loud enough to hear). anyway, it is very difficult to pinpoint and seems mostly to be in my room. i thought i was "hearing things" and told my psychiatrist, now i feel silly. he told me to take some seroquel if i heard it again. now i feel so stupid, but it was so difficult to differentiate. i really think it might be something in my room afterall, making the sound, not in my head, since it only seems to start up in there, and i dont think i hear it anywhere else (not outside or other places). what if my psych doesnt believe me ?