If you hope to record new sounds, you need a microphone. Your microphone situation depends on the kind of Mac you have:
Laptop, iMac. You have a built-in microphone, usually a tiny hole near the screen.
Mac Pro, Mac mini. You can plug in an external USB microphone or use an adapter (such as the iMic, www.griffintechnology.com) that accommodates a standard microphone.
The System Preferences→Sound→Input pane lets you choose which sound source you want the Mac to listen to: external USB microphone, built-in microphone, or whatever.
Actually, there’s a quicker way to change audio inputs—if you know the secret. Option-click the menulet, if you’ve installed it. The resulting menu lists all your audio inputs and outputs, making it simple to switch.
Once you’ve got your microphone situation taken care of, you need to get your hands on some sound-recording software—like QuickTime Player, which is in your Applications folder. (You can use GarageBand to record sound, too, but that’s often like using a pneumatic drill to get out a splinter.)
Choose File→New Audio Recording. Use the pop-up menu to specify the audio quality and sound source (Figure 16-2). Click the round, red Record button and begin to speak; click the square Stop button to finish up. Now you can use the volume slider and the button to listen to your masterpiece.
Don’t adjust the tiny volume ...