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19/06/2002 - Editorial: History of the Sound Card by Saeed Amen

Computers were never designed to handle sound. About the only audio you'd hear from an early computer were beeps, designed to tell you if there was a problem. Computer games manipulated these beeps, to produce truly awful music as an accompaniment to games like Space Invaders. However, surely there was more to sounds than beeps? Thankfully a company from the Far East recognised this, and made the original Sound Blaster sound card for the now ancient ISA bus. It could record real audio and play it back, something of a quantum leap. It also had a MIDI interface, still common on sound cards today, which could control synthesisers, samplers and other electronic music equipment. It could "create" sounds by using FM synthesis, which were not that realistic but were nevertheless better than simple beeps. The quality of the audio was 8 bit 11 kHz, so sounded roughly like an AM radio.

The sound card is quite a complicated piece of electronics. The most important parts are the ADC and DAC. The ADC (Analogue-to-Digital convertor) takes in analogue signals, for example from a microphone and converts them to digital signals for the computer to store. The DAC (Digital-to-Analogue convertor) does the opposite. However, in the future there will be no need for either, since both speakers and microphones will be able to directly record and playback digital signals directly. The heart of a CD player is also the DAC. CD players tend to sound better than the average, because they generally cost more and are simpler devices. Hence the DAC component of a CD player tends to be more expensive (and thus better quality). Having said that, the quality of DACs on sound cards is improving all the time.

The advantage of digital audio (ie. storing audio as 1s and 0s) is that no matter how many times it is copied it remains identical, and does not degrade like analogue sources, such as vinyl. The next major development for sound cards was the leap up to 16 bit 44.1 kHz stereo audio, ie. CD quality. However, this posed problems for the archaeic ISA bus, which had problems playing back and recording more than one track at the same time. This effectively meant it was difficult to use your computer to make phone calls on the internet (since you couldn't talk and hear at the same time!) or use it as a multitrack audio editor (for musicians). The PCI bus solved this problem. Nowadays virtually all soundcards are PCI. Currently we are seeing 24 bit 96 kHz sound cards emerging, which promise even better sound quality than CDs! Some sound cards also decode Dolby Digital sound, so you can connect computer speakers to them for surround sound, when playing back DVDs. High-end sound cards also come with digital inputs and outputs, letting you bypass the sound cards convertors and use external ones.

Recently there has been the advent of the USB and Firewire buses. These enable you to connect fast external devices to your computer. Sound cards attached to the USB bus cannot playback as many tracks simultaneously as a PCI sound card. However, for people other than musicans this is hardly relevant. Also being external they can be used on more than one machine and on laptops, which notoriously have poor sound cards. There are also several external Firewire sound cards. These are quite expensive and designed to playback and record many tracks. Consequently they are a waste of money if all you do is watch DVDs or play MP3s on your computer.

Sound on the PC has come a long way since all those beeps twenty years ago!