The Physical Properties Of Sound

Kelvin Sholar

Sound has two types of properties or qualities which belong to it. They are either physical properties (or qualities related to things perceived through the senses) or psychical properties (or qualities related to things perceived through the mind).

There are several physical properties of sound. They include frequency, amplitude (or intensity), duration, onset, envelope and waveform. Frequency describes the rate at which sound pressure changes. Amplitude describes how strong sound pressure wave changes are. Duration describes how long a sound is, while onset is the point in time at which the sound begins. Envelope describes form of sound on a macroscopic level; it is the special way that the amplitude of the sound changes over time.

Waveform describes the form of sound on a microscopic level. Different wave shapes give character to the sound of the voice or instrument. There are four basic kinds of periodic waveforms, based on their shape: sine, square, triangle and sawtooth. Each waveform imparts a certain timbre or sound quality to performance media: for example, the timbre of the flute is imparted by the sine waveform, a sawtooth waveform determines the timbre of strings, the recorder’s timbre is given by the triangle waveform, while the woodwinds have a square waveform.