I actually heard a couple of noises the first was like a dog howling and that was early like 7 am. The second was a humming sound that happened at school. Again I asked if anyone heard anything, no and I was in a crowd.
I can hear very high pitched noises others can't. It sucks, because it causes migraines. But it comes in handy with ghost investigations, because a high pitched noise may not be heard by a person, but they still "pick it up" and it will give them "the willies" making them think they are sensing a "presence" or "spirit", when really--it's just a high pitched noise.
You probably have a touch of astral hearing. You might be able to sometimes hear noises on the astral plane. When people scry they "look" onto the astral, and it can be heard to, without actually projecting.