Digital Audio Information Sound Basics Sound originates from a disturbance of the air by any object. The local region of air has increased energy caused by the motion of the air molecules. This energy spreads outwards in sound waves. Subjectively we often refer to a sound as being a high pitch sound or a low pitch sound.
Frequency is the most fundamental quantitative unit of sound.
For this sound to have a major significance it must be comprised of multiple high and low pressure zones following each other. The time between the intervals of high pressure zones defines a cycle, and frequency is defined as the number of cycles per second. Hertz simply means cycles per second. If we talk about the fundamental frequency of the concert 'A' when played by a piano, then we are referring to 440 Hz. The range of human hearing is from 20 Hz to 20,000 Hertz.