Just to be helpful, here's how to remove the alert sounds from your keyboard sound-volume keys. If you use WireTap to record audio, those volume alert-sounds will be recorded every time you adjust the volume using your keyboard, so this will help. (This won't remove the alert sounds when adjusting the volume with the menubar volume control, as far as I can tell.)

System Preferences > Sound > Uncheck: "Play feedback when volume keys are pressed"

Works for me!

Hope that helps somebody out there.

--- wildtrack