Sound

:This article is about compression waves. For other meanings, see sound (disambiguation).

Types of sounds

Noises are irregular and disordered vibrations including all possible frequencies. Their picture does not repeat in time. The noise is an aperiodic series of waves.

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Sounds that are sine waves with fixed frequency and amplitude are perceived as pure tones. While sound waves are usually visualised as sine waves, sound waves can have arbitrary shapes and frequency content, limited only by the apparatus that generates them and the medium through which they travel. In fact, most sound waves consist of multiple overtones or harmonics and any sound can be thought of as being composed of sine waves (see additive synthesis). Waveforms commonly used to approximate harmonic sounds in nature include sawtooth waves, square waves and triangle waves.

Related Topics:
Pure tone - Sine wave - Overtone - Harmonic - Additive synthesis - Sawtooth wave - Square wave - Triangle wave

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While a sound may still be referred to as being of a single frequency (for example, a piano striking the A above middle C is said to be playing a note at 440 Hz), the sound perceived by a listener will be colored by all of the sound wave's frequency components and their relative amplitudes, as well as how the sound changes over time (see timbre.) For convenience in this article, however, it is best to think of sound waves as sine waves.

Related Topics:
Piano - Middle C - Note - Timbre

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