What is Sound Card in computer SOUND CARD A Sound Card can be defined as an expansion card that is capable of producing sounds using certain computer programs. Hence, it can be also called an audio card. It is a peripheral device that can be attached to an ISA (or) PCI slot of a motherboard. The following are the functions of a sound card. Audio Interface (i) Synthesizing sounds (ii) Used as MIDI interface (ii) Converts analog-to-digital (iv) Converts digital-to-analog (i) Synthesizing Sounds This refers to the process of generating sounds. Earlier components were capable of producing only a beep sound. But from the 1980s with the invention of special add-on cards called sound cards a variety of sounds could be synthesized. There are three methods that can be used for generating the sounds, they are Frequency Modulation (FM), wavetable, and physical modeling. (ii) Analog Vs Digital The best examples for analog and digital are the sounds and data of the computer respectively. Analog signals are a collection of waves that can traverse through the matter. Digital signals are nothing but electrical impulses containing O’s and 1’s. Hence a sound card can be used for converting computer digital data into analog data. For this purpose, it contains four components that are present on its printed circuit board. They are, (a) Analog-to-digital converter (ADC) (b) Digital-to-analog converter (DAC) (c) ISA (or) PCI interface that can attach the sound card to the motherboard. (d) Input and output connections for the microphone and speakers. However, there are some sound cards that contain a CODEC chip (Coder/Decoder) instead of different ADC and DACs. This chip has the ability to carry out both conversions. Working of ADC’s and DAC’s in a Sound Card ADC Working:- Assume that a user wants to record his voice on the computer. For this purpose, using a microphone he speaks. This microphone is connected to the sound card. Then the analog-to-digital converter (ADC) will convert the analog waves into digital data that the computer understands. This is done by sampling or digitizing the sound by considering some specific measures of the wave at regular intervals. DAC Working:- In order to play the sound that was recorded earlier ai DAC is used. The DAC would carry out the same steps in reverse order so as to play the sound through the speakers. The number of measurements per second is known as the sampling rate. A card should possess a high sampling rate in order to obtain accurate waves. But high rates will also lead to a decrease in sound quality which is called distortion. There are two ways of measuring the reduction in sound quality. They are, Total Harmonic Distortion (THD) It can be represented in the form of a percentage( %) Signal to Noise Ratio (SNR) It can be measured in terms of decibels SOUND CARD STANDARDS NAME YEAR SAMPLING FREQUENCY AUDIO BIT DEPTH CHANNELS TYPE PCjr 1984 122 Hz to 125 kHz 16 volume settings 3 square wave tone; 1 white noise PSG PC Speaker 1981 6 bit 1 pulse-width modulation PWM MPU-401 1984 1 MIDI in; 2 MIDI out; DIN sync out; and tape sync IO; metronome out MIDI Tandy 1000 1984 122 Hz to 125 kHz 16 volume settings / 6 bit 3 square wave tone; 1 white noise; and 1 pulse-width modulation PSG Adl lib 1987 49.716 kHz 64 volume settings 6-voice FM synthesizer, 5 percussion instruments FM synthesizer Covox 1987 8 bit 1 DAC Roland Sound Canvas 1991 32 kHz 16 bit 24 voices Roland MT-32 1987 32 kHz 16 bit 8 melodic channels; 1 rhythm channel Sound Blaster 1989 22 kHz 8 bit 1 DAC; 11-voice FM synthesizer FM synthesizer AC97 1997 96 kHz 20 bit 6 independent output channels PCM Gravis Ultrasound 1992 44.1 kHz 16 bit 16 stereo channels Intel High Definition Audio 2004 192 kHz 32 bit up to 15 independent output channels PCM Environmental Audio Extensions 2001 8 simultaneous 3D voices Hardware