Monday, May 28, 2001		On Hardware

Sound cards are more than just a beep
Jasjot Singh Narula

INITIALLY, when Personal Computers (PCs) gave a beep, it depicted that either the system was on or an error had occurred while executing the command. Today sound cards provided on the system have changed the way the computer "interacts." Net, PC and CD music relies heavily on this.

The sound card enables a PC to "say" more than just a beep. It is a plug-in optional circuit card for a PC. It provides a high-quality stereo sound output under a driver’s or software’s guidance.

In mid-80s, the Ad Lib Inc. and Creative Labs Ltd. Were the first ones to manufacture the sound cards that were designed on an 8-bit ISA slot on the IBM PC motherboard. The 8-bit refers to the rate at which the card processes the flow of data.

Turtle Beach Systems, another manufacturer of multimedia components, developed a 16- bit sound card. The 16-bit sound card offered 44 KHz resolutions that could produce CD-quality sound.

In the beginning sound cards used FM (Frequency Modulation) technology to create sounds. This technology takes the tones of different frequencies and combines them to create an approximation of a sound. To achieve a new goal in synthesis technology, the Wave Table Synthesis technique was developed for higher accuracy. Wavetable synthesis works by recording a tiny sample of the actual instrument. Today most of the sound cards are equipped with this technique.

1. ISA slot sound cards — Initially the sound cards took new dimensions through ISA (Industry standard Architecture) slot from 8-bit to 16-bit technology. But these are now obsolete.

2. PCI (Peripheral component input) slot sound cards — These are one of the latest and inexpensive ones. The best part for the PCI-slot sound card is their fast rate of data transfer as compare to the ISA slot ones, which makes the audio quality better.

3. Integrated sound chipset — These sound cards are inbuilt on the motherboard and feature good quality sound output. Intel integrated sound chipset motherboard are higher in demand. These integrated sound chips have distinctive features but they do not provide optimum result that a user can get from a PCI slot sound card.

4. 3-D Sound blaster card — They are a craze among the audiophiles as these provide "3-dimentional audio quality." A 3-Dimentional effect is where you hear the sound, but the volume is determined by the card’s polyphony. The latest 3-D sound blaster card can play 32 and 64 voices simultaneously.

Earlier sound card were equipped with half-duplex quality that allowed unidirectional transmission of data. This meant that the sound was either punched into the PC for processing or played back through speakers at distinctively separate time.

In this era of the Net, people are using the voice-enabled protocols. This requires simultaneous two-way communication. Today, sound card feature full-duplex operations.

The sound card consists of different components that are listed below:

a) Digital signal processor (DSP) — Its main function is to handle computations.

b) Digital to Analog converter (DAC) — For the conversion of output audio.

c) Analog to Digital converter (ADC) — It is for the conversion of input audio.

d) Flash memory — To store data for a short period of time.

e) Muscial instrument digital interface (MIDI) for connecting to external music equipment.

f) Jacks for connecting speakers and microphones i.e. line in and line out.

g) A game port for connecting a joystick or gamepad.

The digital analog converter and analog digital converter provide the means for getting the audio input and output of the sound card. The digital signal processor looks out for all activities or processing going on and also takes care of any changes or alterations to the sound, such as echo or reverb.

With the sound card, the user can play music from CDs or sound files as .wav or MP3 format files. He or she can also record audio in various media from external source (microphone or tape player), synthesise sound and process existing sound. The PCI slot sound cards are easy to install.