The shape of a church sanctuary determines many things.
It tells us how well the room will sound, how much the audio system
will cost (and how well it will perform), and gives insight to what
the minimum requirements are for platform lighting and video projection.
This short article will give some of the basic pro’s and con’s
of room shapes. Much of this information is based off H.I.S. System
So where do you put the boundaries of a room? When standing in
a room, the ceiling is typically above you, the floor below you,
and the walls to the front, rear, and sides of you. This we know.
When it comes to a church sanctuary though, the exact placement
of these individual pieces becomes critical if you desire an acoustically
friendly space. In my opinion, an acoustically friendly sanctuary
is one where the minister or other leader can be heard and understood
clearly, the musicians can hear each other and play together, the
choir sounds full and strong, and the congregational singing is
warm and exciting.
The overall shape of the room is just the beginning point for achieving
good acoustics; you still need to ensure other steps are taken to
make the room the best it can be. If your sanctuary is rectangular
and yet the shell of the building is square and the sanctuary walls
are built improperly, you’re really left with a square sanctuary,
acoustically speaking (in the low frequencies). Also, even with
the best overall shape, the walls themselves must have the correct
sub-shape to them. That is, if your sanctuary is rectangular (which,
as you’ll read, is one of the better shapes), but if the walls
are left as large, flat surfaces, this isn’t helping the room
(it’s actually creating problems).
Before we get in above our heads, let’s start from the beginning
and talk about the various room shapes and overall layout of each.
First, the square room with the platform along one wall of the
room. Such a room is a very poor choice simply because two of the
three dimensions are identical. I can only hope that if you have
a square room that the ceiling height isn’t the same as the
wall length, i.e., a cube. Sound waves reflect between parallel
surfaces. A square room has two sets of parallel walls which results
in flutter echoes and standing waves. Because the two dimensions
are identical, the standing waves formed between the two sets of
walls will be identical as well. That is to say, by having the two
dimensions the same, you’ve doubled your problems by default.
While a square room can be designed or fixed later to sound pretty
good, it’s not a good choice to begin with, when you have
a choice in new construction.
bad choice (above)
If you must have a square room – or if you’re already
stuck with a square room, put the platform in one of the corners
and treat the room more like a fan-shape when it comes to seating.
Better choice for platform location in a square room(above)
Then there’s a rectangular room; the shoebox shape. If the
platform is along one of the shorter walls, you’ll have a
very nice space that some regard as “the best sounding room
shape”. Again, you can’t forget to deal with the parallel
walls; the overall shape is good, but it needs some minor shape
adjustments to be great.
Very good rectangle room layout, except the parallel surfaces (above)
Take the same rectangular space and put the platform on one of
the longer walls. Now you have seating which often wraps around
the platform sides, ensuring the pastor must turn his back to 1/3
of the congregation at a time to see those seated on one side or
Poor layout for rectangular room (above)
I thought that in acting class and speech we were taught to never,
never turn your back on your audience… Because of this, you’ll
need to install a couple video projectors, screens, and cameras
to ensure everyone can see pastors’ face at all times. The
audio system must now cover a wider horizontal plane; this costs
more money than simply covering a deeper room. Many such designs
cost 2 to 3 times more than if the room had been used by length
rather than by width. Taking all of this into consideration, what
are the acoustics like? Well, we rely on lateral (side) reflections
to help with intelligibility and to give warmness to the sound in
the room. Because the side walls are far apart, the congregational
singing won’t be as strong, warm, or as together as it should
be among other things. Hmm, it costs more and it doesn’t perform
as well. Huh. Let’s build it!
One of the main reasons people like rooms that are not deep but
very wide is because it seems to bring the congregation closer to
the platform. While this is true to a point, why do the people need
to be so very close? Is it because they need to be able to lip read
the pastor because the audio system is so poor? We all know the
seats at the very back of a long room seem far away, but did you
know that if the platform is lit properly that it will appear to
be much closer than it really is? So, using the room by length,
lighting the platform properly, and putting in a cheaper audio system
means we have good acoustics, people can see, and the audio system
will cost less and perform better. Now, to please the pastor, all
we need to do is build a small thrust stage out into the congregation
and place some seating around it. Now the pastor has that warm,
intimate feeling, not to mention a good sounding and singing church.
What about fan-shaped rooms, aren’t they good? Sure, as long
as they aren’t so wide that we’re back to one of the
problems with rectangular rooms being used by width. The pastor
shouldn’t have to turn his head more than 60-degrees in either
direction. If he does, the room is too wide.
Bad curved rear wall in fan-shaped room (above)
Many fan-shaped rooms get a nice curved back wall; this is a real
problem that must be avoided at all costs. A simple flat wall is
still a problem; you need to work with different shapes and ensure
it’s diffused properly.
Better than a curved rear wall, but this flat rear
wall still needs adjustment so it's not a big problem (above)
Triangles, pentagons, hexagons, octagons….are these any good?
Any room with an even number of sides where each side is the same
length will be a problem. They’ll perform similar to the square
room. If anything, the wall lengths should all be different. Rooms
made up of an odd-number of walls can work well, assuming there
are no parallel surfaces again.
Rooms that are round, oval, or having similarly large concave shaped
surfaces must be avoided at all costs. Rooms like this are best
left for museum whispering galleries.
Should the floor be flat or sloped? That depends on a number of
other factors, and is somewhat a negotiable choice. A flat floor
is most easy to construct properly, but a sloping floor has advantages
for both sight lines and acoustics.
Ceiling slope going the wrong direction (above)
Ceiling slope going the correct direction (above)
What about the ceiling? Does it need to be really high, or can
it just be 15 feet or so? Well, the minimum height for a room seating
200 people should be 19 feet. For every hundred and fifty more seats,
the ceiling height should be an extra foot higher, until you reach
35 feet. Then you can cut back to adding only an extra foot for
every additional 200 seats. This ensures the overall volume of the
space is proportional to the quantity of seats, plus it ensures
enough height for a proper speaker system to be installed.
Should the ceiling be flat or sloped? If you intend to slope the
ceiling from front to back, be sure the ceiling is lower over the
platform than it is at the rear of the room. That is, don’t
make the ceiling high over the platform and low over the congregation.
Remember the bell of a trumpet, clarinet, tuba, or bullhorn. The
opening gets wider away from the original sound source. This is
because sound travels outward in a spherical pattern. Thus, the
wave front is expanding. If you try to use the room backward, you’re
asking the sound waves to be compressed into a smaller space –
this doesn’t have good results at all.
Should the ceiling be constructed with drywall, wood, suspended
tiles, or something else? That depends a lot on the rest of the
room and how it’s finished.
There are many, many variables to work with when it comes to choosing
something as (seemingly) simple as the shape of the sanctuary. What
I always like to go back to is the Bible. In 1 Kings, we’re
given a description of Solomon’s Temple. Different translations
and other references give us quite a few details of this space.
My associate, Joseph De Buglio built a scale model of the Temple.
He tested the acoustics of the space to see what the sound waves
were doing. He found that the shape, construction materials, and
furnishings all led to a very well performing room. If the room
were to be used for traditional music, it was fine the way it was.
For organ, piano, and choir, it just needed a strip of carpet down
the center isle. For a full-blown contemporary church, it needed
padded pews. That’s it; those were the only real differences.
I figure, if it was good enough for God, it’s good enough
for me. This isn’t to say other shapes and designs are not
good; not at all. What I’m saying is that we’ve already
been shown how to do it right, so there should be no reason why
we build rooms that perform more like warehouses and funeral parlors
than a church sanctuary.
Blake A. Engel
All Church Sound