Even before the launch of STS-135 there is plenty of noise recorded while the astronauts were speaking to each other and the people on the ground. Do the astronauts hear the same noise that is recorded. Why is there so much noise?
No answers have been ventured so I'll post anecdotal experience based on my one launch.
Can't recall if the crew hears all ground comm that is recorded on the loop, but it is not uncommon for one or more of the crew's mikes to be breaking vox with normal breathing. That can become noticeable.
Really, the most remarkable thing I remember wrt the subject question is that while I could barely hear the 3 mains when they started, the SRB's were definitely audible from inside my helmet - sort of a low, incredibly powerful rumble/roar (couldn't really detect the loud snapping sound that was evident to spectators on the ground). Then, of course, there was the vibration...