Sound Synthesis

There are now a few different methods by which a sound card produces sound.

The oldest of these methods is called FM synthesis. FM synthesis does not produce high quality reproductions of the instruments they are supposed to be. How it works is this: the sound card is equipped with a synthesizer chip. This chip produces sine waves which are the beginning of sound. By combining several different sine waves, the chip is able to create complex waveforms, and these waveforms are supposed to be as close as possible to the actual sound of the instrument. In reality, though, the sound is “canned”. FM synthesis cards are older cards, and are not much used today.

Most boards sold today use what is called wavetable synthesis. What this means is that in the on-board ROM is stored actual recordings of the instruments. These recordings are then used, by changing the pitch of and blending, to create much more life-like sound reproductions. Such sound cards must have ample memory on board to store the sounds. Many sound cards are expandable so that you can add memory and create your own wavetable recordings. The quality of the wavetable synthesis is a function of the quality of the recordings. Short, low-resolution sound tables produce cheap sounds.

The third method of sound reproduction is called physical-modeling synthesis. In short, a card using this method would emulate the vibrating sound system of an instrument (such as a guitar string) by creating a similar model through software. The sound chip would create wave vibrations that would act like a physical wave. This method of sound creation is incredibly life-like and is thus increasing in popularity. It is usually found on higher end sound cards. Creative Labs was one of the first to implement the method. The Creative Labs AWE64 Gold has 14 instruments re-created through this method.