Hi sweety!
I feel for you, I too have problems with ringing or hissing sounds in my ear, doctor said it was caused by stress but its pretty constent and if I don't distract myself I become focused on it and it almost drived me mad. Do you know why you have this rinign/buzzing?
With regards to the loud bang you heard, I have had the same thing also, just as I start to fall a sleep I hear a bang and it startles me and makes me want to sit bolt up right, my heart races I feeling tingly all over and the sensations are so intence I have to get up and walk around.
Sometimes I hear the bang and other times I don't and wake up with the same sensations. I feel like Im losing my mind worry that Im going insane. Hearing fealing and seeing things that are not really there type thing. Sometimes this happens several times a night to me and I cant get any sleep, end up taking a Xanax at 3 in the morning just to get some zzz.
I don't know if your prob and my prob are the same but from what I read it sounds similar.
Take care
Cassie