Source
From Audacity Manual
Select the input source (such as microphone or line-in) for your recording device: - On Windows (except Vista) and Linux, in the dropdown selector on the right of the Mixer Toolbar.
- On Windows Vista and Mac, at Recording Device on the Audio I/O tab of Preferences, or in Device Toolbar. The source will be shown as part of the parent device (for example, High Def Audio Card: Microphone). If necessary, Mac users can choose the input source at Apple Audio MIDI Setup.
Note: many USB or Firewire recording devices don't have a choice of inputs, so this step is not necessary. If in doubt, see the documentation for your device.
Tip: To record audio playing on the computer, Windows and Linux users can choose the "Stereo Mix", "Wave Out", "Sum" or comparable input source.
Back to Recording Audio .
To Getting Started.