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A sound card (also known as an audio card) is an internal computer expansion card that facilitates economical input and output of audio signals to and from a computer under control of computer programs. The term ''sound card'' is also applied to external audio interfaces that use software to generate sound, as opposed to using hardware inside the PC. Typical uses of sound cards include providing the audio component for multimedia applications such as music composition, editing video or audio, presentation, education and entertainment (games) and video projection. Sound functionality can also be integrated onto the motherboard, using components similar to plug-in cards. The best plug-in cards, which use better and more expensive components, can achieve higher quality than integrated sound. The integrated sound system is often still referred to as a "sound card". Sound processing hardware is also present on modern video cards with HDMI to output sound along with the video using that connector, previously they used a SPDIF connection to the motherboard or sound card. ==General characteristics== Most sound cards use a digital-to-analog converter (DAC), which converts recorded or generated digital data into an analog format. The output signal is connected to an amplifier, headphones, or external device using standard interconnects, such as a TRS phone connector or an RCA connector. If the number and size of connectors is too large for the space on the backplate the connectors will be off-board, typically using a breakout box, an auxiliary backplate, or a panel mounted at the front. More advanced cards usually include more than one sound chip to support higher data rates and multiple simultaneous functionality, for example digital production of synthesized sounds, usually for real-time generation of music and sound effects using minimal data and CPU time. Digital sound reproduction is usually done with multichannel DACs, which are capable of simultaneous and digital samples at different pitches and volumes, and application of real-time effects such as filtering or deliberate distortion. Multichannel digital sound playback can also be used for music synthesis, when used with a compliance, and even multiple-channel emulation. This approach has become common as manufacturers seek simpler and lower-cost sound cards. Most sound cards have a line in connector for an input signal from a cassette tape or other sound source that has higher voltage levels than a microphone. The sound card digitizes this signal. The DMAC transfers the samples to the main memory, from where a recording software may write it to the hard disk for storage, editing, or further processing. Another common external connector is the ''microphone'' connector, for signals from a microphone or other low-level input device. Input through a microphone jack can be used, for example, by speech recognition or voice over IP applications. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「sound card」の詳細全文を読む スポンサード リンク
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