# Audio Waveforms.

Essay by BARTONIOUSUniversity, Bachelor's May 2003

Waveforms

Introduction

Sound is created by vibrations such as in a guitar string, vocal chord or speaker cone. These vibrations disturb the air molecules near them, forcing molecules together and raising the air pressure slightly. The air molecules that are under pressure then push on the air molecules surrounding them, which push on the next set of air molecules, and so on, causing an area of high pressure to move though the air. When these pressure waves reach us, they vibrate the receptors in our ears, and we hear the vibrations as sound. When you see a waveform that represents audio, that waveform represents these pressure waves. The zero line in a waveform is the pressure of air at rest. When the line swings up it represents higher pressure. When the line swings down it represents lower pressure.

Waveform Terms

The amplitude is the change in pressure from the peak of the waveform to the trough.

A cycle is the amount of time it takes a waveform to go from one amplitude, all the way through its amplitude changes, until it reaches the same amplitude again.

The frequency of the waveform is how many cycles it goes through each second, where 1 Hertz (Hz) is 1 cycle per second

A Waveforms phase is the measure of how far through a cycle the waveform is.

There are 360 degrees in a single cycle, so if you started measuring with 0 degrees at the peak, the waveform would be at 180 degrees at the trough, and back up to 360 degrees at the next peak.

The wavelength is the distance in centimetres between two points with the same phase.

When two of more sound waves meet, their amplitudes add to and subtract from each other.

If the peaks and troughs of the waveforms...