Thanks everyone for the responses.
My story is that on the 19th December last year I went to a party at a restaurant with a live band and was seated next to a huge loudspeaker (last to arrive). It was uncomfortably loud, and I've spent many days since wishing I had made an excuse to leave rather than endure the excessive volume. Not wanting to be rude and leave, social pressure convinced me to stay despite feeling uncomfortable in that environment. In hindsight, and a warning to anyone else in this situation: your hearing and sanity is far more precious than whatever perceived rudeness you will display by walking away.
A few hours later I left the party with muffled hearing. I don't recall noticing any ringing at that point.
My hearing seemed fine the next day.
A couple of days after the party I came down with a nasty viral infection (sore throat, fever, laryngitis, cough).
This finally cleared up by new years day (Jan 1).
January 7th (19 days after the loud party) was the first day that I noticed the high pitched sound inside my head. It's been there ever since, though I seem to have some days when I don't notice it, and there was a period when I was on holidays overseas and I didn't seem to be aware of it for a week or so (was I habituated? Or was it actually gone for a while?).
Lately its been bothering me again. Thankfully it's not very loud so I'm able to get to sleep ok. My T is a high pitched noise, which I can only describe as a glassy static sound somewhere between a ringing tone, a hiss and a whistle. I can voluntarily create a very similar sound in my ears by clenching the muscles in my neck, only my T is a higher pitch than that. It seems to be directly inside my head, almost as though it's coming from something resonating inside my brain.
I started this thread to help determine the cause of my T - was it the loud party or the infection? The T didn't seem to start until around 2 and a half weeks after the party. But, based on your responses, it seems that T can start several days / weeks after noise exposure so it's still likely to have been the cause. Or perhaps it was a combination of both the noise and the infection...
After hoping and wishing that it would eventually go away on its own, I finally decided to make an appointment with a local ENT. The appointment is tomorrow. I searched online and found an ENT with great reviews, but I'm not expecting much from him based on the comments I've seen here...
Emotionally I'm coping ok on the whole. Some days I feel like I'm able to move past it, other days it really gets me down and I start ruminating on the mistake I made by going to that party, feeling angry at myself, wishing more than anything I could go back and change the course of events. Part of me wishes that the viral infection was the cause - at least then there was nothing that I could have done about it, whereas I could have used earplugs or left the party when I was feeling uncomfortable.