Mute the volume adjustment quack sound
Nov 12, 2010 - 5 Comments

You can mute the quack sound that your Mac makes when adjusting audio levels by adjusting a system preference.
- Open “System Preferences”
- Click on “Sound”
- Uncheck the box next to “Play feedback when volume is changed”
Now your Mac will be silent when adjusting the volume level with the keyboard controls. This is a good feature to disable if you’re often in quiet places like a library. If you spend a lot of time in quiet areas, you can also mute your Mac startup sound.

You can also hold shift while changing the volume to temporarily disable the quack sound.
You can also hold shift while you use the volume keys, to mute the quack temporarily
You can also hold shift & alt whilst pressing the volume keys for finer control over the volume level.
[...] [via OS X Daily] [...]
You Rock Thanks, that sound speaks to wake my kids when I try to lower the volume of a really loud video.