I have similar problems a while back with no sound when played in Windows 7.
O/S : Windows 7 Ultimate 32bit
CPU : Intel Core i5 760 2.7 Ghz
Mem : 4Gb 1600
Grafix : NVidia GeForce 9800 GTX+
Sound: Creative Sound Blaster X-Fi Platinum Fatal1ty Championship Series
I am using all the latest drivers
and no sound until I came across the post by Prv8J0k3r
(Thanks a heap). I downloaded and update the Rapture3D drivers and voila! All the sound came back without needing to set any compatibility mode or setting Bioshock to DirectX 9 .