Spherical acoustic wave

Professional Definition

An acoustic wave, whose front is a spherical surface.

In acoustic physics, a spherical wave is a model of sound propagation from a point source in an isotropic medium (that is, one that has identical properties in every direction). A key feature of this wave is that acoustic energy spreads over an increasingly larger surface area of the sphere. This leads to a phenomenon described by the inverse square law: doubling the distance from the source results in a fourfold decrease in sound intensity (a drop of 6 dB).

Acoustics in Simple Words

To understand a spherical wave, imagine inflating a balloon. The surface of the rubber is the front of the sound wave. At the moment of launch (at the mouth), the rubber is thick and has a vibrant color (high energy). As the balloon grows, the same amount of rubber must cover a much larger area, making it thinner and more transparent (energy weakens). Exactly the same happens with the sound emitted by a speaker in open terrain – the further away you are, the "thinner" the energy that reaches you.

Summary

A spherical acoustic wave is a theoretical and practical model of sound propagation from a point source in all directions. It is crucial for calculating the decrease in loudness with distance in environmental and open acoustics.