Sound is represented in term of Air Pressure (Y axis) Time (X axis)
The amount of change is air pressure is "amplitude"
Each wave is called a cycle. Cycles are measured in HZ (hertz) and a measured by the second.
For humans to hear sound it must be between 20 and 20,000 Hz (cycles per second)
Our ability as humans to hear a wide variety of the sound spectrum deteriorates as we age - 20-20kHz.
The combination of many frequencies in one sound is considered a complex tone or a complex wave.
What is Digital Sound
A similar process to film is used for capturing analogue sound. However unlike film captured at rate from around 25 fps up to hispeed camera rates for sound thousands of samples are required to capture a good audible sound.
In order to capture the highest frequence of sound the ear can perceive of 20kHz we can assume a sample rate of at least 20,000 cycles per a second would be required.
Aliasing - If frequencies are heard that are not in the sound frequency they are "folded" back into the frequency range.
CD Quality Audio is at a rate of 44.1kHz.
Using two bytes (16bits) a wide range of amplitude values is the standard for audio CDs. Lower bit rates result in limited sound quality and realism.With increased computing speed we can now capture due for recording at 96bits.
What is DSP.
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