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The Term 'Audio'

July 16th Fact-of-the-Day

The term 'audio' is widely used by both the general public and engineers, but what exactly does it apply to? Is the sound of your voice audio or does it only become audio when it is converted to waves of electrical energy by a microphone? The term 'audio' applies equally to acoustic waves (sound waves) and to representations of acoustic waves by waves of any type or form of energy, such as electrical waves, radio waves, light waves, magnetic waves; or by any mechanical representation of those waves, such as waves in the groves of a phonograph (gramophone) record. The audio frequency spectrum includes only frequencies that can be heard by humans. Frequencies below about 20 Hz are felt as vibrations more than they are heard as sound, so they are arguably not audio. Frequencies higher than about 20 KHz can be heard by very few humans, so they also are not audio. However, despite the technical meaning of the term, the Hi-Fi marketing industry commonly refers to frequencies both below and above human hearing as audio. ©2005 Martek International All rights reserved.

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