ksimboy,
thanks for the reply. When I was with the HEART we visited Abbey Wood to talk to the J office. When asked about the relative noise levels of the J and K we gained the clear impression that inside at least the J would be worse than the K. As I retired from the RAF before the J entered service I did not have a chance to check on this.
When I was on 30 Sqn I 'minded' a university team who were researching the internal noise levels on the K. I have a copy of the report somewhere but remember that the opening para went something like this 'the noise in the Hercules cargo compartment is like being in a disco with a pneumatic drill operating nearby' !
Sounds like the J has a couple of such drills.