- The definition of a sound card is a plug in card for a computer that records and plays audio files through the computer speakers.
An example of a sound card is what turns your iTunes files into music on your Macbook.
Also called a "sound board" or "audio adapter," it is a plug-in card that records and plays back sound. Supporting both digital audio and MIDI, sound cards provide an input port for a microphone or other sound source and output ports to speakers and amplifiers. Sound circuits are typically built into the chipset on the motherboard, but can be disabled if a separate sound card is installed. See Sound Blaster, AC'97 and HD Audio. Digital Audio Digital audio files contain soundwaves converted into digital form. Sound cards convert the digital samples back into analog waves for the speakers using digital signal processing (DSP). See sampling, digital audio and DSP. MIDI MIDI files contain a coded representation of the notes of musical instruments such as middle C on the piano. Taking considerably less space than digital audio, MIDI files require a wavetable synthesizer on the card, which holds digitized samples of the instruments. See MIDI.