Every computer manufactured today is equipped to record and play back sound. Sound capabilities are provided by a soundcard, either integrated into the computer's circuitry or installed as a separate component plugged into a slot on the motherboard. Typically, this preinstalled sound card, however, is of mediocre quality, intended simply to play back system sounds and music for recreational listening.
If you are digitizing analog recordings (LPs and cassette or reel-to-reel tapes), the quality of audio your workstation can produce will be greatly improved through an upgrade to the sound card supplied with the computer. Until a few years ago, this meant installing or replacing a card inside the computer. With the introduction of Firewall and USB2, the most convenient way to upgrade your computer's sound system is to purchase an audio interface, a stand-alone component that plugs into the computer's Firewall or USB2 port. Also, an independent, external audio interface can easily be moved from one computer to another, which simplifies upgrading and replacing the encoding workstation.
Audio interfaces range widely in features, functionality, and cost. Some of the more popular manufacturers are M-Audio, Edirol, Tascam, and Mark of the Unicorn (MOTU). A few years ago, a typical stock sound card installed in a computer offered 16-bit resolution and a 48 kHz sampling rate. As use of digital audio technology has grown, audio interface technology has become more sophisticated, offering deeper resolution (24-bit is now standard) and faster sampling rates (up to 192 kHz). Three survey respondents offered information on the specific brand and model of the audio interface used for their project, and in all cases, the interface offered 24-bit resolution and a sampling rate of up to 96 kHz.5.5Some studio-quality audio interfaces offer 32-bit resolution, and inevitably the technology will continue to advance over time.