How Your Computer Works (Part 5) - Sound Card

^{A sound card}

Today we'll be talking about an unsung hero of your computer: the sound card. Many motherboards come with integrated sound (that is, they're capable of producing audio even without a sound card), so why even bother with a sound card at all? Come to think of it, is it really a big deal that computers can make sound?

Well, at one point it was.

Computers made before the 1980's could only make beep sounds. These beeps were just to serve as indicators that the computer was working (or wasn't) and to allow hardware specialists to better diagnostically examine computers. Think of these beeps the same way you would the lights in your car near the odometer. When the oil is low, a light comes on. If something is wrong with your ignition a different light comes on. You get the gist.

Anyway, computer programmers started getting clever and using the beeps to make music in their games. This is the origin of the earliest computer music.

During the 1980's this all changed when manufacturers began to release cards specifically for sound. The basic mechanism behind sound cards has been the same since that time. Digital information (signal pulses of 1 and 0) is converted to analog information (sound waves) and in this way sound is produced. The reverse happens when sounds are instead recorded.

^{8-channel digital to analog converter (DAC) Cirrus Logic placed on Sound Blaster X-Fi Fatal1ty.}

Playing Sound

Most sound cards use a digital to analog converter (DAC) to convert digital data to an analog format. The signal then travels to an output device for amplification like headphones or a speaker. This is where quality comes into play. You see any time there's a signal traveling there is always going to be some amount of data loss. This can change based on the signal type and the medium. Digital technology and circuitry has become adept at preventing this, but analog tech is still very vulnerable to signal loss.

So what exactly is signal loss? It's when an amount of information is lost in transit or through transformation. So if you have a really good sound card but your speakers are low quality, you'll notice a lower sound quality than if they were both high quality (the same applies for headphones).

^{4-channel stereo analog-to-digital converter (ADC) made by Wolfson Microelectronics placed on an X-Fi Fatal1ty Pro sound card.}

Recording Sound

A sound card can take recordings by digitizing sounds (analogy information). It does this by taking a series of rapid 'snapshots' of the sound wave, sort of like an audio flip book and converting this information to a digital signal using the analog to digital converter (ADC). The closer the snapshots are together and the more accurate each is, the higher quality the recording will be. The number of measurements per second is referred to as the sampling rate and is measured in kHz. The faster the sampling rate (the closer the snapshots), the better the recording.

The sound card has evolved a lot. Innovative solutions such as 3-D sound (sound changes as your character moves through a virtual world instead of same sounds and music regardless of whether your character is facing the sound, etc.) continue to make sound more and more immersive. If you were on a tight budget building your PC, the sound card would probably be the thing you could afford to skimp on without feeling too bad (unless you're really into music recording and listening). Still, it's a great piece of tech that has enriched all of our lives.

Other Posts In This Series :
How Your Computer Works (Part 4) - RAM & Hard Drive