• A computer measures the amplitude of the waveform at regular time intervals to produce a series of numbers.

• Each of these measurements is called a sample.

• Fig below illustrates one period of a digitally sampled waveform.

• Each vertical bar represents single sample. The height of the bar indicates the value of that sample.

Fig: Sampled Waveform

• Audio means "of sound" or "of the reproduction of sound". Specifically, it refers to the range of frequencies detectable by the human ear approximately 20Hz to 20kHz.

• 20Hz is the lowest-pitched sound we can hear, 20kHz is the highest pitch we can hear.

• Sound also takes more storage space. 5 seconds of sound uses more than 400000 bytes of storage, whereas a minute will consume more than 5 MBs.

• Various compression techniques are used for decreasing the storage while sacrificing some fidelity (exactness of sound).