Comment 6 for bug 790608

As was stated at the time, the sound-theme-freedesktop is meant to be a seed base theme welcoming contributions. I would encourage you to make any non-Ubuntu specific changes and push them into the this theme upstream. Obviously certain sounds you will want to keep unique to yourselves (such as login/logout sounds) but otherwise you should just try to improve the base.

Certain sounds do need to be in the base theme (like those for testing speaker setups) and there is likely little point in replacing them in any derived themes. Other things will eventually go into this theme but from external sources. Games for example will likely put some of their in-game sounds into the directory hierarchy of the sound-theme-freedesktop tree with their upstream install process. Then, if a derived theme wants to customise that game's sounds' they can do so easily. That is the intention.

The actual number of sounds in the fdo theme are pretty minimal. So as I said, I would simply try to improve them.

While I still think it's a bit of a bastardisation, I would be much happier with you removing some of the sounds from the base theme that you know you override or disable in your Ubuntu theme (such as login etc.) to save space, but that said, it would be nicer to keep things pristine if possible. I would certainly ensure that the sounds specified in the fdo theme are kept if at all possible as these really are the basic set of sounds needed for a desktop system.

Hope that answers your question to some degree.

I look forward to contributions to the s-t-fdo in due course :p