Speakers , headphones , earphones ,
and other audio output devices rely on sound cards or integrated sound
card functionally to produce sounds such as music , voice , beeps , and
chimes. Sound cards contain the chips and circuitry to record and play
back a wide range of sounds using analog-to-digital on version and
digital –to-analog conversion , as described .
To
record a sound , the sound card must be connected to an input device ,
such as microphone, audio CD player , portable media player , or DVD player
. The input device sends the sound to sound card as an analog signal.
The analog signal flow to sound card’s analog – to – digital –converter
(ADC). The ADC converts the signal into digital (binary) data of 1s and
0s by the sampling the signal at set intervals.
The analog sound is a continuous waveform, with a range of frequencies and volumes . To represent the wave form In a recording , the computer would have to store the waveforms value at every instant in time . Because this is not possible , the sound recorded using a sampling process. Sampling involves breaking up the waveform into set intervals and representing all values during that interval with a single value.
Several factors in the sampling process--- sampling rate, audio resolution , and mono stereo recording ---affect the quality of the recorded sound during playback.
Sampling rate , also called sampling frequency , refers to the number of times per second the sound is recorded . The more frequently a sound is recorded , the smaller the intervals and the better the quality .
The sampling ferquency used for audie CDs, for example , is 44,100 times per ssecound , which is expressed in hertz (HZ) as 44,100 Hz . DVD-Audio , BD – ROM audio traks , and HD-DVD audio traks use sampling rates between 96,000 Hz and 192,000Hz.
Audie resolution--- defined as a bit rate such as 8-bit, 16-bit , or 24-bit --- refers to the number of bytes used to represent the sound at any one intrval .Asound card using 8-bit resulation , for example represents a sound with any 1 of 256 values (2*). A 16-bit sound card uses any 1 of 65 , 536 values 2 power 16 for each interval. Using a higher resolution provides a finer measurement scale, which results in a more accurate representation of the value of each sample and better sound quality . With 8-bit resolution , the sound quality is like that of an AM radio ; 16-bit resoulation gives CD-quality sound , and a 24-bit resolution is used for high – quality digital audio editing .
Mono or stereo recording refers to the number of channels used during recording . Mono means that the same sound emits from both the left and right speaker during playback; Stereo means that two separate channels exist in the recording : one each for the left and right speakers . Most sound cards support stereo recording for better playback.
After the ADC converts the analog sound through sampling , the digital data flows to the digital singla processor (DSP) on the sound card . The DSP then requests instructions from the sound cards memory chip on how to process the digital data. Typically , the DSP then compresses the digital data to save space. Finally , the DSP sends the compressed data to thr computer’s main processor , which store the data in WAV, an MP3 , or other audio file format.\
To play a recorded sound , such as a wav , an MP# or a CD track , the main processor retrives the sound file from a hard disk , CD , or other storage device . The processor then sends the digital data to the DSP, which decompresses the data and looks to the memory chip to determine how to recreate the sound .
The DSP then sends the digital signals to the sound cards digital-to-analog converter (DAC), which cionverts the sound in digital format back to an analog electrical voltage . An Output device , such as a speaker , uses an amplifier to strengthen the electrical voltage . This causes the speaker’s cone to vibrate , recreating the sound.
All of this happens in an instant . The next time your computer beeps or chirps , sonsider the complex process required to make that simple sound .Then , insert your favorite CD and hear your computer come to life with the music provided courtesy of the sound card .
The analog sound is a continuous waveform, with a range of frequencies and volumes . To represent the wave form In a recording , the computer would have to store the waveforms value at every instant in time . Because this is not possible , the sound recorded using a sampling process. Sampling involves breaking up the waveform into set intervals and representing all values during that interval with a single value.
Several factors in the sampling process--- sampling rate, audio resolution , and mono stereo recording ---affect the quality of the recorded sound during playback.
Sampling rate , also called sampling frequency , refers to the number of times per second the sound is recorded . The more frequently a sound is recorded , the smaller the intervals and the better the quality .
The sampling ferquency used for audie CDs, for example , is 44,100 times per ssecound , which is expressed in hertz (HZ) as 44,100 Hz . DVD-Audio , BD – ROM audio traks , and HD-DVD audio traks use sampling rates between 96,000 Hz and 192,000Hz.
Audie resolution--- defined as a bit rate such as 8-bit, 16-bit , or 24-bit --- refers to the number of bytes used to represent the sound at any one intrval .Asound card using 8-bit resulation , for example represents a sound with any 1 of 256 values (2*). A 16-bit sound card uses any 1 of 65 , 536 values 2 power 16 for each interval. Using a higher resolution provides a finer measurement scale, which results in a more accurate representation of the value of each sample and better sound quality . With 8-bit resolution , the sound quality is like that of an AM radio ; 16-bit resoulation gives CD-quality sound , and a 24-bit resolution is used for high – quality digital audio editing .
Mono or stereo recording refers to the number of channels used during recording . Mono means that the same sound emits from both the left and right speaker during playback; Stereo means that two separate channels exist in the recording : one each for the left and right speakers . Most sound cards support stereo recording for better playback.
After the ADC converts the analog sound through sampling , the digital data flows to the digital singla processor (DSP) on the sound card . The DSP then requests instructions from the sound cards memory chip on how to process the digital data. Typically , the DSP then compresses the digital data to save space. Finally , the DSP sends the compressed data to thr computer’s main processor , which store the data in WAV, an MP3 , or other audio file format.\
To play a recorded sound , such as a wav , an MP# or a CD track , the main processor retrives the sound file from a hard disk , CD , or other storage device . The processor then sends the digital data to the DSP, which decompresses the data and looks to the memory chip to determine how to recreate the sound .
The DSP then sends the digital signals to the sound cards digital-to-analog converter (DAC), which cionverts the sound in digital format back to an analog electrical voltage . An Output device , such as a speaker , uses an amplifier to strengthen the electrical voltage . This causes the speaker’s cone to vibrate , recreating the sound.
All of this happens in an instant . The next time your computer beeps or chirps , sonsider the complex process required to make that simple sound .Then , insert your favorite CD and hear your computer come to life with the music provided courtesy of the sound card .
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