I had this happen in my sleep also, but it sounded like a dog barked right in my ear. I was so disoriented to wake up (not from a dream, but a loud noise). It happened 2 days before I completely and suddenly loss my hearing in one ear. Several weeks later, the noise occurred again, but I haven't had any other notable side effects. I'm checking into candidacy for a cochlear implant for my ear that lost all hearing (sudden hearing loss).