Here is the article on Tinnitus I referred to in my previous post.
I like the work of Peter Russell. I've read a few of his books and I follow him on Facebook. A few weeks ago he posted this article about a high-pitched ringing in the head, which many people reported "hearing" before or after awakening. I started hearing it about 2 months before Self-realization and still have it. I heard Rika Markel mention it in her interview with David Bingham and forwarded this article to her, which is how we got in touch initially.
I actually went to a doctor and the tests ruled out standard tinnitus. I also contacted a cranial-sacral therapist about it, although I never took treatment. Through research, I assumed it was something to do with ascension and the raising of my vibration, and as it stopped bothering me, I just don't bother about it anymore. Then Peter's article popped up where he states that it could actually be the sacred sound OM!
Anyway, here's the link. Let me know in the comments what you think about this and if you have had any similar experiences.