Click the 'More Information' link on this page for all the other audio-based quartz screensavers I've made. I may try to combine some of these, but keeping CPU use low is the priority.
To use these create (if it doesn't already exist) a folder called "Screen Savers" in your ~/Library folder and place the file there. It will then be available in ScreenSavers preference pane.
Note: If you are using a PowerMac or other computer without a built in microphone, you need to either adjust your default input in Sound Preference Pane so the screensaver can "hear" it, or email me or leave a comment if that doesn't work, so I can provide a version that monitors the line in. (I don't have a computer like this to test it on.)
All previous versions and others are available in the More Information link on this page.