Devices Preferences

Interface

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; on OS X, Core Audio; and on Linux, ALSA (default) or OSS. Generally you will want to use the default. On more modern Windows machines, DirectSound should produce lower latency.
Using: Gives the version number and build date of the PortAudio Audio I/O interface library with which Audacity was built.

Device: Selects the device used for recording.
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.