How to control system volume

[Ken Norris]

I looked in the archives and couldn't find much.

Since I'll be using TTS and other audio feedback a great deal, a complete
standard for controlling system volume is important to me, i.e. a set of
handlers (built-in or otherwise) that can _temporarily_ take control of the
sys volume while the app is running, then return it to its former setting
when leaving the app (such as opening other app windows or quitting, etc.).

Is there any help for it?

Ken N.