I have had tinnitus for years, and have never felt comfortable with noise cancelling headphones. Purely anecdotal, of course, and even regular headphones are uncomfortable after awhile, but active noise cancellation is unbearable for me
Whenever I use noise cancelling headphones (or really any headphones), I always have something playing even at a really low volume to drown out the tinnitus.
I'd rather just have the ringing in my ears than ringing PLUS something else. There's something distinctly different between ANC and true silence, and despite several attempts I've never found an ANC that proved otherwise.