Simplest way to record voice on Macbook Air
Scenario 1: You're both in the same room

Open up QuickTime Player. Select File -&gt; New Audio Recording.... Make sure the source is set to Built-in Microphone (see screen shot below). Hit the big red Record button. Talk away.



Scenario 2: You're using Skype or something like it to converse

This is a little trickier but not impossible. You'll need the SoundFlower app from Cycling '74. If you're using Skype you'll set it's audio output to be the SoundFlower input. Then in QuickTime you'll set the audio input to be SoundFlower's 2-channel output. This routes the audio from Skype in to QuickTime. Record as above.