Device Toolbar
From Audacity Manual
Audio Host
Selects the particular interface with which Audacity communicates with your chosen playback and recording devices. On Windows the choice is between MME (default) or Windows DirectSound and on Linux, between ALSA (default) or OSS. On OS X, Core Audio is used. Generally you will want to use the default. On Windows XP or earlier and a recent computer, DirectSound should produce lower latency.
Output Device
Input Device
In most cases (for example, the inbuilt computer sound device), each entry for input device consists of the input type (such as microphone), followed by the name of the audio device the input belongs to. If a device only has one possible input (for example, a USB microphone), only the name of the device will be listed, with no input type.
Input sources are no longer chosen in Mixer Toolbar.
Input Channels
- 1 (Mono), 2 (Stereo) or the number of channels that are provided by the drivers of your sound device. On most inbuilt sound devices, especially on Windows, only mono or stereo will be available. For some devices on Windows, choosing Windows DirectSound in "Host" above may be more likely to reveal options for recording more than two channels. On some devices capable of recording more than two channels, an explicit "multi" device may appear in the "Device" dropdown for recording all the channels simultaneously.