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  • How Sound Cards Work
Technology Articles > Hardware > Sound Cards > How Sound Cards Work

The computer that you are using at the moment has a sound card in it. It is, as the same suggests, a component installed in the computer that allows your computer to emit sound. Some computers have sound cards that are attached to the motherboard, while some will have a better one installed in order to increase the quality of the outputted audio.
In bygone years the only sound that a computer could process was beeps. This was first used to signal something (to warn you, perhaps) and was then used in early video games to create music, changing the length and pitch of the beeps to do so. Obviously this was not very advanced, so when the sound card was introduced in the 1980s it allowed things to get much more advanced. Computers could now produce proper audio for things like DVDs and could also record audio.
We can hear sound in the world because the waves make our eardrums vibrate. This is analogue sound, whereas computers work digitally. Computers communicate through a series of 0s and 1s, created by electrical impulses. The sound card then translates the digital information of the computer and the analogue information from outside.
A sound card at its most basic is a printed circuit board that makes use of four components. This then translates the analogue and digital information through an analogue to digital convertor (ADC), a digital to analogue convertor (DAC), an ISA or PCI interface to connect it to the motherboard and input and output connections for a microphone and speakers. Some sound cards will use a decoder chip instead of separate ADCs and DACs.
Sound cards help when recording audio. If you speak into a microphone the ADC turns the analogue sound waves into digital data so that the computer can understand it. To do this it takes specific measurements of the sound wave at frequent intervals. The samping rate is the number of measurements per second and is measured in kHz. The higher the sound card’s samping rate then the more accurate the audio it translates is. Playing audio through the speakers is the opposite of this process, as performed by the DAC.
Sound cards have evolved over time and no longer just have speaker and microphone inputs. Some have a Digital Signal Processor, a microprocessor that handles some of the computer’s CPU workload by carrying out the analogue and digital conversion process. Some cards will also have their own memory and connections for things like multiple speakers (to enable surround), electronic instruments and USB connections which allow digital audio recorders to link up to the sound card.
A sound card will use software to let it operate with other applications on the computer. This includes drivers, which are specifically designed to talk to the operating system. There is also something called application program interfaces, which are set standards to help the software communicate with the sound card.
Hopefully this article has helped you understand how the sound card works and the role of it in your computer. It is a vital component and one that is often taken for granted nowadays. When you are next watching a film in surround sound, remember that not long ago all a sound card could produce was a beep.