User Guide

Sound System Design Reference Manual
indicated by the density of the dots on the page; near
the source they are very close together and become
more and more spread out at greater distances from
the source.
The reverberant field is indicated by the circle
dots. Their spacing is uniform throughout the
enclosed space to represent the uniform energy
density of the reverberant field.
Near the source the direct field predominates.
As one moves farther away, however, the ratio of
black dots to circle dots changes until the black dots
are so few and far between that their presence can
be ignored. In this area one is well into the
reverberant field of the room. At some particular
distance from the source a zone exists where the
densities of the circle and black dots are equal. In the
illustration, this zone takes the form of a semicircle;
in three-dimensional space, it would take the form of
a hemisphere.
5-13
Figure 5-16. Direct and reverberant fields, directional loudspeaker
Figure 5-15. Direct and reverberant fields, non-directional loudspeaker