What Is a Sound Card? - Definition, Function & Types

Lesson Transcript
Instructor: Paul Zandbergen

Paul is a GIS professor at Vancouver Island U, has a PhD from U of British Columbia, and has taught stats and programming for 15 years.

In a digital age, where our ears sense airwaves but computers communicate in digital data, there is a need for sound cards. Learn how they enable digital audio to be heard, and the various types that are used today. Updated: 09/09/2021


Most of your music collection is probably in digital format, either on CDs or as files on your computer. In order to be able to listen to your music, a sound card converts digital data to analog sound waves you can hear. The output signal is then connected to a headphone or set of speakers. You can also use a sound card to record audio with a microphone.

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Sound Card Features and Functions

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.


You can use the computer's internal speakers to listen to audio, but what if you want to plug in a headset or set of external speakers? Several types of audio connectors exist. These are 2.5 mm mono, 3.5 mm mono, 3.5 mm stereo, and 6.35 mm stereo.

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