Comment 2 for bug 619013

This annoys me too. It has been decided to stop support for alsa OSS-emulation from within the kernel without offering a viable alternative for exactly this application.
Read this: https://answers.edge.launchpad.net/ubuntu/+source/linux-meta/+question/121773

As an unsatisfying work around you can change the sound-volume with e.g. alsamixer (from alsa-utils). Therein you can tune the volume of 'line' or 'cd', depending where you connected the sound-output of your tv-card but changing sound volume from within tvtime is broken!
The best way to solve this is one adds direct alsa-support to tvtime. Until that happens, I hope the ubuntu devs and sound engineers will reconsider their decision to completely terminate alsa-oss emulation since OSSp (thought/intended as successor) does not (yet) work for this kind of hardware-constalation.