I have a very low, very quiet but persistent drumming in my left ear. It feels like it's deep inside and when it is completely quiet, all I hear is this low drum, cyclical, very regular. I'm not sure if I'm feeling pressure in my left mastoid bone area as well (may be due to my teeth clenching), but it's been going on for a number of days. It sounds exactly like a base drum and occurs every 1-2 seconds