I'd try it at your doctor's dose for 30 days. Maybe 600 mg is all you'll need. 1200-1800 is commonly cited for protection from loud sounds. There's no specific dose for tinnitus; but the article I read had a women take 2 grams a day. She was taking it for depression, but, as an unexpected side effect, her tinnitus got better!
In general, it's best to take the smallest effective dose of any supplement or drug. This is because long term no one knows if they will do damage to our systems. NAC, while not a supplement in Sweden, is probably used similarly to its medical indication in the US: to detox, especially from acetaminophen.
Taking it 3x a day is also good. You'll keep a study level in your blood. This should be more effective for tinnitus then allowing the levels to fluctuate.
Your hyperacuasis should also improve.
Thanks Jazz. I will start at the recommended dose then. I am still a bit confused however. Why is it only available as effervescent tablets here in Sweden while you guys swallow them whole as regular pills? Is it really the same stuff? The main purpose for it here is for chronic bronchitis and stuff like that. It's thinning out the mucus or something. You could also inhale it through a machine, but normal pills arent available.