* * * You may want to copy or print this. It is long.. * * *
The following article was first written by Joseph De Buglio in 1988 and
published in 1991 for Your Church Magazine. It has been Updated Jan. 1996
and April 2008.
TROUBLE SHOOTING CHURCH ACOUSTICS,
THE PRO'S AND CON'S.
Why Band Aids Don't Work well in Open Heart Surgery.
© By Joseph De Buglio 1996 - 2008
Since most churches have a problem or would wish to avoid a problem, here
are some after the fact solutions.
In old cathedrals of Europe and in a few churches in North America, pillars
were used to tune the church. Slots or holes in the back of a pillar were
cut to select the offending frequencies. By adding sand, or as done recently
in Chicoutimi, Quebec, adding blown insulation, you can tune the pillars.
If a mistake is made, the sand can be removed from a hole at the base of
the pillar. The pillars greatest effect is on the sound quality of the
Pipe Organ and congregational singing. Pillars tuning is still being done
today and it is possible to retrofit an existing church with pillars.
Ash pots were first used by the Greeks, then the Romans and later in Northern
Europe. The technique is very simple and effective. Where ever there was
a known or planned acoustical problem, clay pots of various sizes would
be built into the walls of the church or theatre. The most common walls
were the back walls and rear corners. After many trial and error tests,
an employee of the church would fill or empty the pots with ash for various
function. Today this same technique could be used. You can replace the
ash with fiberglass insulation which is reusable. Us a silicone spray on
the fiberglass and it will reduce the dust and keep the fibers from falling
apart. A better alternative would be an adjustable Helmholtz Resonator.
Please read the book Architectural Acoustics, David M Egan, published by McGraw Hill, 1988 or "The Masters Handbook of Acoustics" Second Edition F. Alton Evert, Tab Books 1989 for further details.
Slotted blocks have been around for a long time. Slotted blocks were often
combined with the clay pot system. Today, the slotted block is a very attractive
system that stands on it's own. The principal is simple. Take a standard
8 x 8 x 16 inch block. Cut a slot from top to bottom of the block to a
certain width for the frequency you want to control. Add some fiberglass
inside of the block. When finished, you can paint or wax the block or cover
with curtain or cloth. The block companies that manufacture these blocks
also make different size chambers within the block and the have different
surface finishes that don't need to be painted. These blocks work well
for mid and low frequency control and they are generally interior blocks.
Depending on who the manufacturer is, this system has many names. The most
common appearance of the system is 12" x 18" x 3" flat panel.
Usually the back of each unit has a mounting deck that raises the units
about an inch from the wall. These units are effective for mid and high
frequency control. Although the manufacturer claims are accurate, they
are very misleading. If you have a room with an internal volume 50,000
cubic feet, the literature will say that all you need is 1 or 1.5% of material
to treat the room or 750 units. What they are not saying is that 3 of the
walls have to be cover from floor to ceiling to get the desired results.
Using these products requires more than a siding scale to figure out.
Split Face Blocks.
A split faced block is nothing more than a block with an exposed shape.
There are many patterns and styles. Usually the exposed shape is 2 inches
deep or less. These blocks are also often called Architectural blocks and
they are treated a decorative block. The Acoustical properties of these
blocks are very limited. Some times you will see a 6 or 8 foot ring of
these blocks in the upper half of a school gyms. Although an Architect
will state that he chose those blocks for their acoustical properties and
smile for his wise choice, an acoustical expert will notice right away
that two of the walls should have had the spit face block from the floor
to the ceiling and an eight foot ring in the other two walls. The spilt
face block is not very efficient in distributing or absorb sounds. The
split faced blocks combined with other systems can be very attractive.
ASC Tube Traps
A functional Bass trap, high frequency diffuser and mid range absorber
makes this product the most effective. Although they cost a few dollars
more, you need far fewer of them when compared to other sound control objects.
ASC tube traps were designed originally as a recording studio product.
When this product was unleashed to the church community, it has literally
performed miracles as some minister would express its. The beauty of the
product is three fold. First is being able to trap a lot of bass sounds
in room corners in a small package. Almost all churches have corners including
domed churches. Bass always builds up in the corners. ASC Tube Traps traps
the bass without reducing the high frequency range noticeably. Secondly
it absorbing mid range sound. By spacing the traps at difference widths,
you can change the amount of mid range absorption. The third effect is
diffusion. The diffusion occurs from 500 hertz and up. Usually you don't
want to absorb high frequency in a church. The Tube Trap can maintain the
singing quality of a church while fixing the low frequency problem areas.
As a side benefit, in every installation of ASC Tube Trap that I have visited,
the organist always make comments like, "there is more bass coming
out of the organ" or "the music is easier to follow and play.
I didn't realize how much poor acoustics were restricting our ability to
perform" (Scott Tyler, St. Paul's United Church, Bowmanville, Ontario,
Can.) ASC products can be used on their own or be used with other products.
RPG Diffusors. (Reflection Phase Grating)
Diffusion is often used to solve acoustical problems. For years, the acoustical
community was looking for a diffusive surface that gave a uniform diffusion
of sound energy. Such a system was invented by Manfred R. Schroeder, a
professor at the University of Gottingen, Germany and at AT & T bell
Laboratories at Murry Hill, New Jersey. The panels have many different
sizes and shapes to accommodate almost any acoustical condition. The panels
have long wells which are cut to different 1/4 wave lengths deep. The well
depths have a very specific pattern. Each panel is based on the "Maximum
Length Sequence Code". Today the general term is Diffraction Grating
and many acoustical engineers design their Diffraction Grating Panels.
The RPG diffusors is trademark of a ready made, of the shelf, effective
system of, non-patented panels which are primarily made of wood. The Following
is a Quote from the book, The Master Handbook of Acoustics, Second Edition,
by F Alton Everest (TAB Books)
"In churches, there is always conflict between the intelligibility
of the spoken work and conditions for full enjoyment of the music. The
rear wall is often the source of reflections which create disturbing echoes.
To make this wall absorbent is often detrimental to music conditions. Making
the rear wall diffusive, however, minimizes the echo problem while at the
same time conserving precious music and speech energy. Music directors
or often faced with the problem of singers or instrument players not hearing
each other well.... Surrounding the music group with an array of reflection
phase grating diffusors both conserves music energy and spreads it around
to achieve ensemble between musicians."
The combination of RPG products and ASC Tube Traps offers the most versatile
and complete solution to any church with acoustical problems.
Pressure Phase Diffusers (PPD)
PPD's are just a fancy combination of absorber, Helmholtz resonator and
diffusing panel. The panels are built within a 2 x 4 ft frame. These are
custom made for each project. Since acoustical problems come in layers,
this combination panel reacts to the various acoustic effects in a single
package. Since most churches have limited wall spaces, PPD panels are used
in the worst of acoustical conditions. The thickness of the panel, the
curve of the diffuser and the manipulation of the cavity within allows
a single panel to do the job of several panels that would take up to 4
times the wall space using other panel system.
PPD panels are made under license by church members. This is a low cost
alternative to RPG or ASC products
Tectum (Spaghetti Board)
Tectum is one of those products that you love to hate. When used properly,
Tectum tiles panels work great. However, because they are so cheap to buy
and every Architect has a "Guide Book" from the manufacturer,
Tectum usually gets installed in a broad and indiscriminate way. As a result,
Tectum gets installed in such a way that it solves one problem very well,
but it creates other problems. In a Gym or a Cafeteria, the latitude in
using Tectum is quite broad, but in a church, there is a fine line between
how much you use, how it is installed and which surfaces it is installed
Tectum is an inert fiber board made from tree roots that comes in thickness
from 1 to 4 inches. When exposed, the panels look like compressed spaghetti.
Although it is paintable, the Guilford Cloth covered products are better
in a church. When painted, the Tectum will shift in frequency.
Sonex is a patented foam system. In comes in square panels from 1 to 4
inches thick. These panels are very efficient high frequency absorbers.
Their best use is for attenuating high frequency in a church. A very effective
application of Sonex is for foyers which are disturbing people in the sanctuary.
It is rare for a Sanctuary to have a high frequency problem. If you need
Sonex, use it sparingly and be aware that you could be creating a bass
problem - a problem you did not have before.
Carpets and Padded Pews
Before we even talk about Carpets and padded pews, we should answer the
question as to whether you need them or not!
There are two major conditions for having bare floors and hard seating.
The first is your worship service. Is always going to be
If your church meets 3 or more of these conditions, then carpeting and
padded seating may not be desired. For all other churches, carpeting and
padded seating can be used indiscriminately. Once most worship spaces have
more than 60% of the seats occupied, the bodies of people are more absorptive
than what is under them.
- classical or traditional
- as a high mass
- you only do acoustical performances
- you have more that a 24 rank pipe organ
- You have a high ceiling - where the ceiling is about 65% of the width of
the room if the room is a rectangle - (if your church is 50 ft wide, the
room should be 33 ft high or higher
- much of your worship liturgy is in chants or singing or repetitive prayer
- acoustical concerts
- Choral concerts and competitions
But doesn't carpet and padded singing kill congregational singing?
If the rest of the acoustics of the sanctuary is good, then the floor covering
is less important. If a church sound changes a lot, that is not an argument
about floor coverings, that is a red alert that the room has a problem
in several other areas.
There are many well meaning people who tend to perpetuate a myth that a
bare floor in front of the choir will suddenly make the choir sound better.
In a bad room it doesn't matter and in a good room you have to have other
condition to justify having a hardwood floor in front of a choir. These
conditions include room volume, room shape, the management of sound reflections
around the room, the signal to noise ratio of the room reflections and
the room dimension ratio's.
The second reason for a church not to carpet is if the floor of the church
gets flooded from rivers and excessive rain falls.
The reality is, the vast majority of church worship spaces, should be carpeted.
Unless all other acoustical conditions are in play and the sound in the
room is managed properly, carpeted floors and padded seating has almost
no impact on a well attended church. For the slight amount of performance
gain a bare floor can offer, you are better off making people comfortable.
If the room acoustics are already bad, then why make people annoyed and
uncomfortable too. Besides, it costs less to fix the acoustics of a church
with carpeted floor and padded seating.
Electronic Reverberation Systems
The newest and most exciting method of creating a real multipurpose church is with Electronic Reverb Systems. There are several systems available and some custom systems. These are systems that consists of microphones, speakers, amplifiers, electronic digital reverberation and a complex mixing matrix. When adjusted properly, these system can often make good room have many acoustical faces. However, it is a myth that it can correct acoustical problems such as bass build up or standing waves, but, you can often us it to mask minor echoes and in some cases improve intelligibility.
The plan is to make the house of worship sound "Acoustical Neutral."
Make the room quiet, free of obvious acoustical problems and use the reverb
system to create the desired acoustics as needed.
In Europe, there is a successful system called the ACS or Acoustical Control
System from Holland. Although North American installations of such systems
are limited, these systems offer a wide range of real time church simulations
of great cathedrals and concerts halls. There are other systems from Lexicon
- the LARS System and Philip and so on.
When these systems first came out, there was a promise that you could have
great electronic acoustics regardless of the natural acoustical condition
of a space. The reality is, and what has happened is that some venues have
had to kill the room - make the space almost like a dead recording studio
and then add the electronic reverberation. This is not a reality for most
churches. If a church is so dead that it is not useable if the Reverb system
in not working, they will not want it.
It is my opinion that a reverb system added to a room with a good acoustical
foundation can be an advantage for a church that does a wide range of music
from classical choral presentations, acoustical orchestra concerts and
gospel sing-a-long programs. An inner city church that is looking to generate
income to preserve the building as a community center and a church can
get their acoustics controlled, have a reverb system added and charge competitive
rental fees for community concerts. It seems that as more and more inner
city churches close down the fewer places inner city people have to go
for wholesome community programs musical events.
In church acoustics, these are just some of the most common techniques
seen. The cost of a good acoustical system that solves most of your real
major problems can vary. Please note the words "solve most of your
problems". This is due to the fact that some building shapes are so
poor, that rebuilding the church would be cheaper. However, there are
some compromises you can live with. Accepting minor compromises will keep
acoustic solution costs down.
OK, now that you have just received some of the best knowledge on church acoustics available, now you can get the technical books on acoustics design your church acoustics right! Wrong!!! Just because the church down the street did it or you read of a solution in a book, it does not mean that their solution is right for your church. You might have a one of a kind problem (which happens all too often.) Fixing a church is not always easy. There are just to many variables that can be easily over looked. One wrong number in a calculation can cost a church thousands of dollars. I have never yet met a church that had an unlimited budget or offer me a blank cheque. Churches can't afford experiments. Churches need solutions.
Church acoustics is 40% science, 10% art, 40% skill from experience and
10% inspiration. Judging from the many churches that I have visited over
the past 26 years, all you see is 100% perspiration, 100% desperation and
no science. Isn't it time for the church communities to define their needs
and use science, art and skill to set acoustical standard? Lets stop using
a Band-Aid approach to church audio and acoustics.
Some statements and Specs have been blanked out under the understanding
that it is part of the "intellectual Knowledge" guidelines and
were not part of the original article. Such knowledge has value and can
be purchased through investing in the book "
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