Acoustic Sound Sources
Sound Waves and their Properites in Surrounding Media

Acoustic Sound Sources

A sound source is a potentially oscillating medium in which new energy is generated at the source and propagated outward as sound waves.

Sound waves are produced by various acoustic or electronic sound sources in which oscillations are generated at the source and transmitted outward into the surrounding medium.

A sound source which vibrates at a certain frequency and amplitude produces a normal sound disturbance in the surrounding medium which vibrates at the same frequency and amplitude as the vibrating source.

The geometrical dimensions, material substance, density, and elasticity of the sound source, and the actions and forces which cause the source to vibrate, determine the vibrational properties of the corresponding sound wave.

Normally, an acoustic sound source vibrates at a frequency which is related to the length or diameter of the source, and depends upon its various dimensions, mass, density, and tension.

The various characteristics of an acoustic sound source determine whether the corresponding sound wave creates the impression by the ear of a musical tone or a noise. A sound source which is thin and of high density and tension is more likely to produce vibrations which create the impression of a musical tone. A sound source which is composed of thicker material and has a lower density and less tension is more likely to create the impression of a noise.

An obstruction in the path of a normal sound wave propagating in a medium acts as a secondary sound source which causes a change in the angle of direction of the original wave, and under certain conditions causes a change in the vibrational properties of the deflected wave.

Sound disturbances in the surrounding media are caused by stationary or moving sound sources which vibrate freely or by a forced agitation, by the angular rotation of solid bodies which are large compared to the particles in the medium in which they are contained, by the translation of objects or steady flow of wind or other substance through a medium, by compressional or magnetic lines of tension or stress, by interactions which occur at the boundary interface between different media or between different regions of the same medium, or by electromagnetic or electromechanical oscillations.