Free acoustic pole

Professional Definition

An acoustic field in a homogeneous isotropic medium, where reflected acoustic waves do not occur or are ignored.

In the conditions of an ideal free field, sound waves propagate radially from the source in all directions without any disturbances. The fundamental physical feature of this field for a point source is the inverse square law, which states that with every doubling of the distance from the source, the sound pressure level decreases by exactly 6 dB.

Acoustics in Simple Words

Imagine you are floating in outer space (assuming there is air there) or standing on top of a tall pole in the middle of a vast desert. When you shout, your voice rushes forward and never returns. There is no echo, no reverberation, no sound reinforcement from walls. That is exactly what a free field is. In everyday life, we rarely encounter it because we are always surrounded by some surfaces (floor, buildings, furniture) from which the sound reflects, like a ping-pong ball.

Summary

A free acoustic field is a theoretical standard that we strive for in specialized laboratories called anechoic chambers. It is essential for accurately testing loudspeakers and microphones to measure their actual parameters without distortions introduced by the room.