This is a problem that's been plaguing me for a number of beta iterations: the sound is still dropping out.
In Beta 5, even re-loading wouldn't restore sound. At least in Beta 6 you can exit GCIII entirely and reload; that'll bring sound back, but only for a little while. Then it drops out again.
Curiously, the ambient "galaxy" sounds remain, the subtle hiss/background noise of space ... but UI noises and battle sounds are all gone.
Anyone else getting this?