data representation

Sound

Sound is made when something vibrates, creating waves

This means that they change continuously and do not have a measurable value

These sound waves are analogue

Recording and replaying

Sound is analogue so needs to be converted into a set of binary numbers when it is handled by a computer

This conversion is called sampling

Live sound recorded by a microphone is called analogue sound

The microphone converts sound into an electrical signal

Analogue sound is pure and perfect quality

This signal is then passed onto the analogue-to-digital convertor

Sampling

Sampling takes measurements of the amplitude of the sound wave at various points in time

Sampling is a method of converting an analogue audio signal into a digital signal

The computer takes measurements of this sound wave at a regular interval called sampling interval

Frequency

Frequency is the rate at which samples are taken (Kilohertz - thousands of times per second)

Sampling bit depth

A 2 bit binary number number can only represent 4 possible values. This is far too crude for most applications

Low quality - usually uses 8 bit resolution, 256 discrete levels. Maximum value 11111111

8KHz 8bit sample is lower quality than a 44KHz 16 bit sample. However, the file size is much larger

channels

Mono sound has information about only a single channel

Stereo/surround sound will have multiple channels to make use of multiple speakers

single sound stream

Each channel has its own samples.