|South View High School Gym and Baseball Field Back to main menu|
A case study . . . .
all been in gyms, multipurpose buildings, and airports where
we could hear the sound system but we could not understand
a single word that was said. To understand why and how to
correct this problem as in Miller Gym we need to know some
basics about how we hear. Think of a typical conversation.
In a highly reverberant space like a gym or cavernous airport, sound bounces all over the place creating multiple "echoes" of the same words over and over that arrive at different times and intensities at your ears. (Fig - 1) We hear the original speech or direct sound along with multiple instances or "copies" caused by reflected sound.
reflected sound is equal to the direct sound, speech becomes
very difficult to comprehend. Saying it another way, if the
reverb in the room is so bad to cause a competing noise of
sound that is the same amplitude of the original sound, we
will have an extremely hard time understanding the spoken
or sung word. Its because of how our minds and ears work
to interpret the English language.
sound system has nothing to do with how well it delivers
consonant sounds to the listener. Like the three previous
failed attempts I saw evidence of at South View to install
sound over the years, the common assumption is all we need
to do is make sound louder - buy a PA system or what I call "a
yelling machine" because thats all it is.
Fig-2 shows one way to solve the problem. What we need to do is INCREASE the direct sound relative to the reflected sound. Typically acoustical treatment is placed on the offending wall, floor, or ceiling to minimize the reflected energy in the room. This by default will increase the direct to indirect ratio. This would be great in Miller Gym but its very expensive to cover such a large space with enough material to reduce the reverb to an acceptable level. Plus, any athletic facility requires the treatment to take the abuse of various sports activities at additional costs associated with the type of materials that must be used. Bottom line, acoustical treatment was simply not viable because of the expense..
Fig-3 shows another way. If a speaker system is installed 60 feet from the listener as in typical "cluster" or central speaker systems, the sound from the speaker has an opportunity to strike the walls, floor, and ceiling as it spreads out traveling to the listener. What if we moved the speaker closer to the listener? That means the sound doesnt have a chance to spread out as far before reaching the listener. The goal is to focus sound into the listeners seats before it has a chance to spread out striking reflective surfaces causing secondary images.
a lot more to it than just this simple explanation, but you
get the idea. The listener hears the direct sound BEFORE
he / she hears the reflected sound.
this method, the direct to indirect sound ratio was dramatically
improved. Speech clarity is excellent regardless of where
you sit. You still hear the echo because we did not treat
the room for sound reflections. What we did was change
the direct to indirect ratio restoring lost consonant sounds
over distance. THAT IS THE
mind it takes some acoustic testing and sound engineering
skill to choose the right speaker for the specific job. Just
using any ole speaker will not work. Every speaker has its
own acoustic properties that must be known before it can
be considered in any application, particularly something
like this. I'm looking at another school where this IDEA
was used, but the wrong speaker system. Speech clarity is
terrible. The correct speaker system has been chosen and
awaiting approval of the project at this point.
|Fig-1 The reflected sound competes with the direct sound from the source of sound - talker or speaker system.|
|Fig-2 By reducing the reflections in the room with absorption panels the reflected sound is drastically reduced to allow the direct sound to be heard more clearly.|
Fig-3 Move the source of sound closer to the listener
The direct to reflected sound RATIO is dramatically increased. This is the KEY to speech clarity. We want the listener in the direct sound field of the speaker system.
|Fig-6 The system is tuned and time aligned with a NEXIA SP digital processor. Power is by YAMAHA. The rack is located in a locked room. The system is powered up and down by remote control from the removable control head operated in the gym.||Fig-4,5 Six
speakers spaced over each bleecher
section to cover the seating with overlapping ARTICULATE COVERAGE ZONES©.
The speech is crystal clear at every seat.
|South View Baseball Field|
The baseball field was more straight forward.
A similar portable rack was used to house a single amplifier and mixer to power 4 high quality full range speaker systems.
Full range Community speakers were used instead of the typical "PA horns" for far better sound quality.