How Sound Cards Work

Let’s face it. Without sound, PC operations could become pretty boring. Also, the immersion factor in games would be greatly diminished without sound to go along with the graphics.

So how does your soundcard work to provide this detail of entertainment?

Sound cards do two things as a standard operation:

  1. Process incoming signals, as from a microphone or other device that produces sound, including midi capable musical instruments.
  2. Prepares the signal for output to speakers or files, depending on instructions from the program.

At the heart of a typical soundcard lie a number of elements. They are:

Digital Signal Processor (DSP) – this chip handles most of the computations associated with handling and manipulating incoming signals.

Digital to Analog Converter (DAC) – this processes the sound exiting the soundcard into frequencies the human ear can hear and understand.

Analog to Digital Converter (ADC) – This handles incoming audio signals for the soundcard to process.

Musical Instrument Digital Interface, or MIDI, handles signal input from electronic musical instruments, such as guitars and keyboards.

Onboard the soundcard is Random Access Memory, or Flash Memory, which stores data as the card processes input and output. Also, soundcards typically come with game ports for joysticks and jacks for speakers, headphones, and microphone inputs as well as an in jack for plugging in external audio devices like tape players and portable CD players. It is also possible to use this jack to plugin output from a home entertainment center for sound output to your PC’s speakers or headphones.

Soundcards these days come integrated directly on the motherboard, though external cards, especially the more expensive ones, come as PCI plug-ins. Soundcards can play music from CDs and mp3 files, synthesize sounds, record audio from external sources and process existing sounds.

Earlier soundcards created sound by a method called FM Synthesis. This process basically used tones of varying frequencies to approximate the actual sound, such as produced by a musical instrument or a natural sound effect. This was succeeded by Wavetable Synthesis, which in effect, recorded a tiny sample of the actual sound to produce a full rendition of the sound. This process allows for a much truer sound to the original and is half the immersion factor in many games that rely on good sound effects as well as graphics.

In addition, MIDI instruments can be plugged into a soundcard, and with the aid of a music processing program, display a notational representation of the actual music on the PC screen. Or even display the music as an animated sine wave. A musical selection can be recorded, then in turn edited extensively on the computer to produce a final output that may be significantly modified to produce certain effects.

Before the advent of the soundcard, the only sound a PC could produce was a series of beeps. The first hint of what a soundcard might bring was seen in a few PC games where clever manipulation of the narrow frequency a PC speaker could produce resulted in the startling simulation of sound effects far beyond the simple beeps. Then in 1989 Creative Sound Labs produced the first actual working soundcard and ushered in a new generation of games and applications that enriched the PC experience with realistic sound effects and the ability to hear true to life recorded music.

Since then, the soundcard has evolved to produce amazingly accurate sound in 3 dimensions, or surroundsound. Game sound effects was elevated to a new level with the ability for the player to hear positionally generated sound in a virtual game world as one would in the real world. CDs and mp3s can be played with the startling effect of being in a concert hall, or simulate a variety of realistic musical environments, such as a club or studio.

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