Low hum and ringing

My experience of tinnitus is slightly different than other posts and was wondering whether anybody has any ideas. I am deaf in my left ear from birth and have had no tinnitus. About a month ago, I suddenly started to hear a low continuous hum in my ear with very brief pauses which seems external but is not. The hum is accompanied by the "conventional" ringing sound. However, the hum sputters out over the course of a night and is not present for most of the morning but comes back around early afternoon times and sometimes earlier. If I open my mouth to a certain point or jut my lower jaw forwards, the humming stops although the ringing continues. I have not been exposed to loud noises and have no other symptoms. An ENT specialist says there is nothing wrong with the ear. Could there be another cause?