An add-on device that plugs into an expansion slot inside your PC and generates analogue sound signals. The soundcard generates sound from digital data, using either a digital to analogue converter or a FM synthesis chip. Also provides functions to record sound in digital form (using an analogue to digital converter) and control MIDI instruments. Unlike Apple Macs, PCs do not come with built-in sound generation hardware, so to produce sound you need to fit a soundcard. There are three major standards for PC soundcards: AdLib, SoundBlaster, and Windows-compatible. The MPC Level 1 specification states that a soundcard should be able to record sound in eight bits and sample at 11.025KHz and play back sounds at 11.025KHz and 22.05KHz. Some soundcards provide built-in compression for wave files, but there are various methods used. The MPC recommends ADCPM. In addition, many PC soundcards include electronics to generate sounds from MIDI data on board. There are two kinds of MIDI sound generation. FM synthesis simulates musical notes by modulating the frequency of a base carrier wave, whereas waveform synthesis uses digitised samples of the notes to produce a more realistic sound. (See also MIDI, Sample rate and Sample size.)
