ProblemEdit
No music (only)
Cause - Codec conflictEdit
Installed DirectShow filters (codecs) conflict with Oblivion.
Solution: A fresh Windows installation does not have this issue, but the only known solution is to manually correct DirectShow registries to initial state or to install/uninstall K-Lite codec pack which can do the same. Also try a program such as InstalledCodec to mass-disable and enable codecs until you find the one that causes the problem. Another solution is to use Nightmare2013's Codec reset utility, which is available on his/her website Nightmare2013's Codec reset utility v4.1.
Additional InformationEdit
Music can't be heard even though all other voices/effects are fine.