Son of Beast at the final brakes used to have a really really loud squeel i haven't been there in a couple ears so i don't know if it still does this or not.
big thunder mountain railroad, it has random bits of anti rollback all over the track and anti rollback on vekoma's inside is probably not the greatest idea
Ok i found a good one. Turn up the volume on high as it can go and imagine being in that room. It is like its catching onto the second lift of a bommerang and screaming all at once in a small enclosed room. I have to cover my ears and I still jump.
Plus, they say "all clear". Sometimes you wait half a second, and sometimes ten seconds. And notice how quickly it launches too. Its one crazy ride.
And the launch of ttd and hypersonic both hve that hissing sound that is reeeeaaaallly loud. Except hypersonic has this realy loud whoooosh!ing sound when it gets flinged down the track at hyperspeed
the loudest coaster (even not the most annoying) i've been on is Batman & robin : the chiller... it was almost impossible to talk while the train was running... but i missed them [:(]
Well...I don't know if this counts, but Scream at SFMM, has that annoying horn at the beginning, but that's the station so I don't know if that counts. And yes Superman is loud but it's a sexy loudness of pure terror and fun.
Sometimes you gotta sacrifice a little bit of yourself to get the job done.