Representing sound
Sound is the continual vibration of air particles and is an analogue signal. Therefore, we need to convert sound into binary to be able to process and store it using a computer.
A sound card translates between the outside world's analogue information and a computer's digital information. It uses an analogue to digital convertor (Analogue-to-digital convertor. An interface that converts analogue data to digital data.) to change sound into a digital format the computer can understand, and a digital to analogue convertor (DAC) to change digital information into sound that you can hear.
How is sound stored?
Digital sound is broken down into thousands of samples per second.
The process of converting an analogue audio or video signal to digital is when we record sound at set time intervals and is measured in The unit of frequency, symbol 'Hz'. 1 Hz is 1 wave or cycle per second.. 1 hertz = 1 sample taken per second.
Sample frequency is the frequency at which a sample in a sound file is taken. Most music CDs have a sample frequency of 44,100 hertz (samples per second). Each sound sample is stored as binary data.
Sample frequency is influenced by both In computing, the number of bits processed per second. and The number of bits available to store an audio sample..
- Bit rate: How accurate each sample will be. It is the number of bits used per second of audio
- Bit depth: The number of bits of information in each sample, (the higher the bit depth, the higher the quality of the audio)
Analogue to digital conversion
A computer's sound card contains:
- An analogue-to-digital converter (ADC) converts the analogue signal from a microphone to a digital signal for the computer to process
- A digital-to-analogue converter (DAC) converts the computer's digital signal to an analogue one for the listener