890 words - 4 pages

WaveformsIntroductionSound 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 TermsThe 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 secondA 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 line up, they are said to be "in phase". In this situation, each peak adds to the peak of the other waveform, and each trough subtracts from the other trough, resulting in a waveform that has twice the amplitude of either individual waveform.Sometimes the peak of a waveform will line up with the trough of another waveform. The peaks and the troughs cancel each other out, resulting in no waveform at all. Such waveforms are said to be "180 degrees out of phase".In other cases, the waveforms are out of phase by some other amount; this will result in a more complicated waveform than either of the original waveforms. Continuing to add waves will make a more and more complicated waveform.Analogue AudioA Microphone works by converting the pressure waves of sound into changes of voltage on a wire. These changes in voltage match the pressure waves of the original sound. High pressure is represented as high voltage and low pressure...

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