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Alternatively referred to as an audio output device, sound board, or audio card. A sound card is an expansion card or IC for producing sound on a computer that can be heard through speakers or headphones. Although the computer does not need a sound device to function, they are included on every machine in one form or another, either in an expansion slot or built into the motherboard (onboard).
The motherboard on most computer systems has an integrated sound card, which is often sufficient for many users. However, to get higher quality sound you can upgrade to a separate sound card, which uses better and more expensive components.
Audio files on a computer consist of digital data just like any other file on a computer. Sounds we can hear consist of waves that travel through the air - sounds are analog. The primary function of a sound card is to translate between digital and analog information, just like a video card. Sound cards typically have four major components:
-The digital-to-analog converter (DAC), which makes it possible to convert digital data to analog sound
-The analog-to-digital converter (ADC), which makes it possible to make digital recordings from analog sound inputs
-An interface to connect to the motherboard, typically using Peripheral Component Interconnect (PCI)
-Input and output connectors so you can plug in headphones, speakers or a microphone - many computer systems have speakers and microphone built-in, but connectors allow you to use higher quality external devices to play or record sound
On some sound cards, the two types of converters are integrated into CODEC a single coder/decoder chip. Some sound cards also have a digital signal processor (DSP), a built-in processing unit. The DSP takes some of the load of the central processing unit (CPU) to convert between digital and analog. Similarly, some sound cards have their own memory. Sound cards without a DSP or memory will use the motherboard's CPU and memory.
Computer systems typically have built-in speakers, which are reasonably good if you don't turn up the volume too high. If you want to use your computer for some serious music for a party, you probably want to connect a set of external speakers. Relatively small external speakers can be powered using a USB connection, while larger ones need their own power supply. Similarly, most computer systems have a built-in microphone, but you can also connect an external microphone.
Serious audiophiles who use their computer as their sound system will typically upgrade to a high-end sound card, a set of good external speakers, and a good external microphone (if they want to make their own recordings). A high-end computer system can rival dedicated music equipment. In general, with the improvements in sound and video, computer systems have turned into multimedia systems rather than simply computing devices to run software.
Many computers not only have built-in sound but can even drive a surround sound system with up to 7.1 separate channels. For many business applications, plugging a pair of speakers or a projector's audio input into your computer's headphone jack will provide better than adequate sound. Using on-board audio is simple, inexpensive and worthy of consideration.
Internal Gaming Cards
While many sound cards are aimed at gaming applications, they are nevertheless useful in business settings. Gaming sound cards contain separate processors that generate sound, removing the work of creating it from your computer's CPU. They also have their own set of inputs and outputs that frequently have better shielding and, as such, lower noise levels than the inputs and outputs built into your computer. Many gaming cards also have sound enhancement technologies that can help to locate generated sound in 3D space, or equalize it so that it is easier to hear.
Audiophile and Recording Cards
For the ultimate in sound quality, you can also buy special sound cards that are aimed either at the audiophile market or at the professional audio market. Audiophile cards have heavily shielded outputs and analog circuitry that aims to both reduce noise levels and more accurately reproduce sound signals. Pro audio cards add features like having multiple channels of input and supporting professional audio connectors like balanced XLR plugs.
External USB Sound Cards
USB sound cards are available in a range of connections and capabilities. Some are simple devices that add a headphone jack while others are similar to internal professional audio cards. They all have one feature in common: they move sound processing outside of the computer's case. If your computer's audio output is prone to noise, using a USB sound card can usually eliminate the problem. They're especially useful with notebook computers, since the tight confines and heat inside a notebook's case frequently leads to noise that can be audible during presentations.
The picture is an example of a sound card audio ports or audio jacks on the back of your computer, associated colors, and the connector symbols.
-Digital Out (White or Yellow; words: "Digital" or "Digital Out") - Used with surround sound or loudspeakers.
-Sound in or line in (Blue; Arrow pointing into waves) - Connection for external audio sources, e.g. tape recorder, record player, or CD player.
-Microphone or Mic (Pink; Microphone) - The connection for a microphone or headphones. Sound out or line out (Green; Arrow pointing out of waves)
- The primary sound connection for your speakers or headphones. This sound card also has a second (black) and third (orange) sound out connector.
-Firewire (Not pictured) - Used with some high-quality sound cards for digital video cameras and other devices.
-MIDI or joystick (15 pin yellow connector) - Used with earlier sound cards to connect MIDI keyboard or joystick.
Tip: Usually the cables connecting to the devices are also color-coded and will match or be close to the colors the cables connect into. For example, the end of the speakers cable may have a green line or be completely green.
-Audio CDs and listening to music
-Creating and playing Midi