I just noticed something that you could try Dougal.If you start off at a runway in your plane, put on the parking brake so that you dont start rolling and then go to your outside view again and increase and decrease the throttle. Set the propellor to 100 as well. I am wondering if this volume problem is because Flights sound system is taking into account the speed of the air rushing past the camera, so the wind noise of travelling at high speed is affecting the sound of the aircraft. When sitting on the runway the airspeed is basically 0 so the sound should sound alot different.

In the Maule , I can barely hear the engine, the rest are fine

Some people were experiencing weird problems with the sound in the beta if I recall, one person changed to a soundcard from an onboard realtek and they noticed alot of difference. Could be related to soundchips etc and peoples setups.CraigIs it with a specific plane Dougal or all of them?

I too am using the onboard realtek chip. My board is about a year old (see my sig for specs). I find that the sound can, at times, decrease and increase in volume. This appears to be random, and effects the voice level of characters in missions.Since I'm using an onboard chip which relies on CPU cycles, perhaps the CPU is being "taxed" at that moment??? Maybe! I have a SB Augety 4 laying around... maybe I'll throw it back in my box and see what happens!

I'm reporting that I installed the Audigy 4 and the problem still exists. If anyone else is experiencing sound issues, you should add your voice hear. When I send MS an e-mail, I'll reference this post.