Recording audio on the Mac is not made as easy as it should be in Mac OS so you'll need a dedicated app to do it for you.
OnAirRecorder is a simple digital timer that allows you to start, pause and reset recording with a large easy to read timer. The great thing about OnAirRecorder however is that it gives you QuickTime Pro recording functionality without actually upgrading to QuickTime Pro. By clicking on either the audio or movie buttons in the timer, you can connect directly to the pro audio and video recording features in QuickTime and use them.
Once you're recording, you can simply start or pause and stop the timer manually or it will also automatically start and pause or stop the recording features in QuickTime. Alternatively you can just use it as a huge stopwatch.
Simple, quick and utilizing QuickTime Pro without actually having it, OnAir Recorder is an excellent audio and video recording tool.