Switching off internal mic (garage band)

Does anyone knwo how u turn off the internal mic? because if i put the volume all the way down (there is no mute!) if i tap on the table next to it the volume bars move...

Apple Menu > System Preferences > Sound > input... This is the path you followed corect? Unfortunately, to my knowledge, you can only switch off the internal mic if you have another audio input to switch to. My powerbook has an audio line in jack that I can switch to as the main input. This would shut off the internal mic. Also, if you have a firewire or USB device connected, you can switch the input device to the firewire or USB device to shut off the internal mic.

hope that helps