Audacity® is a free software used for recording and editing sounds. This tutorial covers instructions for downloading and installing Audacity 1.2.6 to an Intel-based Mac. Anyone on a Mac can also use GarageBand (part of the iLife suite from Apple) to make MP3 recordings. Please refer to the built-in instructions in GarageBand should you need assistance with GarageBand.
To download Audacity to your Mac...
This is the Audacity interface. You can now begin recording.
Before recording, check your audacity audio settings to make sure that your recording and playback devices are selected: