Noise
I'm not sure what issues they would be. All aircraft are noisy!
There are 2 kinds of helmet in standard use (the mk4 I think and the white helmets!) and don't have a noise cancelling facility, just ear cups and a squelch on the VOX. There is a stringent programme for monitoring degredation of hearing loss in aircrew, and all aircrew do courses on how to look after themselves and recognise symptoms.
The problem you have to look at is what was fine before may not be fine now - look at Oscar Wilde spending time in prison and the front page story on this week's RAF news!
I however have not heard anything about changing of hours reference noise damage- maybe I should head off down the med centre... Who is whistling...