I noticed bug for app-office/libreoffice-bin-4.0.4.2: no sound in impress for presentations, also i tried app-office/libreoffice-4.1.0.4, there no sound too. P.S. On Debian with LO 4.0.3 everything is OK.
This is dupe of the older bug. I still didn't have time to figure out what is wrong compared to my dev box where it works. *** This bug has been marked as a duplicate of bug 456980 ***