Hi!
Last week I bought a new Xbox One with Forza Motorsport 5 Bundle. After some hours I always have a kind of sound problem in the game and it only finish it when i quit the game and restart it.
I’ve tried different cables, sound settings and other games. Reinstall the game, Clear Persistent Storage, and so on. :(((
What can I do? This is horrible. The problem is the same than in this video from Youtube:
A complete Xbox One power cycle (do not just turn the console off/on) will clear this issue. However, note that the issue will return with time. It’s an audio bug that has plagued the game since release and is not likely to be fixed.
Edge is correct, but it’s a platform issue not limited to forza. I had it happen again today while playing and jumped to another game only to find the same problem.
A hard reboot will make it all better 
As Shadow has already pointed out a full reboot is the only thing you can do to correct the sound issue and it’s only a temporary fix, you’ll have to do this every time the sound glitch happens. This has been an ongoing issue since launch.
Thank you for your answers. 
It is saddening.
I second that lads, and yes, it is disappointing.
It’s a bug in the game; a full power cycle should fix it for the time being, and it will definitely return.
I guess you can play for a while, and once the bug surfaces again, you can take a little break.