The Architect
Model 500 & Model 700
Installer’s Guide
A Short Introduction To Equalizers And Acoustics
Magazine reviewers and audio system owners spend much
time critically appraising speaker and other stereo components.
Unfortunately, a phenomenon that has a very large effect upon
sound is not is easily judged or changed. That effect is the
ACOUSTICS of the environment in which you are listening.
Room acoustics is a complicated subject about which entire
textbooks have been written. We simply want you to be aware of a
few basics that have a direct effect on real time audio analysis.
Sound travels in waves, as
you probably learned in junior
high school. In a stereo system,
these waves are created by the
speakers. Like waves in a pond
created by a splash, sound waves
emanate from the transducers
(drivers) in your speakers and
spread out into the room. If your
room were infinitely big, that’s all
there would be to it. But just like
waves in a pond reach the bank
and reflect back, sound waves
bounce off walls, ceilings, and
floors, reflecting, reinforcing and
canceling each other as shown in
the figure above. Since sound is
energy, the way it reflects depends upon the angle of the surface,
the type of material and the frequency of the sound wave. Because
your listening position is likely to be towards the back of the Free
Field waves shown in the diagram, you also get part of the re-
flected Reverberant Field as well.
Now we add the next set of complications: Different frequen-
cies of sound have different wave lengths (a function of frequency
and the speed of sound). Each frequency’s wavelength contrib-
utes differently to the Free and Reverberant Fields because they
are different sizes. For example, a 32Hz bass note has a wave-
length of 35 FEET, while a 16,000Hz note has a wavelength just
under a tenth of an inch. Tiny treble waves can be caught and
neutralized by draperies, carpeting, upholstered furniture and
gangs of indolent Persian cats…while gigantic bass waves simply
slosh back and forth in the room.
Room interaction
Doing the Deed
11
Summary of Contents for Architect 500
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