Our church is considering
replacing the current carpeting. What are the various alternatives
available and what impact do they have on the acoustics?
This is a classic question asked time and time again. Let's examine
the impact of carpeting in the sanctuary. Carpets kill sibilance
- the "tssss" "shhhh" sounds. This takes the
life out of the sonic aire. Carpets have no effect on the vowel
sounds - a, e, i, o, u. The issue with acoustics is, to a significant
degree, the frequency response of the material. Carpet kills treble
and does nothing to the bass.
Generally, carpeted floors are not good for congregational singing.
They leave the singing space too dull and boomy. On the other
hand, if you like the sound of your sanctuary with the current
carpet, then you should replace the carpet with a like carpet.
If it feels too dead, particularly for congregational singing,
consider removing, rather than replacing, the carpet. As an alternative,
you might consider Berber which has a very tight weave and does
almost nothing to the sound, but it is rather expensive.
The point is that hard surfaces support congregational singing
and, generally speaking, churches like to have bright and lively
sounding congregational areas. Many churches have carpeted walkways
and wood or concrete flooring under the pews. This way there is
a quiet entry and exit path with a lively singing space.
Another carpet problem to consider is that when a piano is played
over carpet it dulls the sound. Try adding an office chair plastic
carpet protector under the piano and you'll hear how it brightens
up and starts to actually sound like a real wood instrument. Choirs
are plagued by the same problem. Putting a choir on a carpeted
floor is like pulling out their vocal chords.
In contrast to this, putting carpet on the floors under the chairs
in Sunday school and in office spaces is an excellent idea. The
rooms tend to be smaller and there is a lot of "creature
noises", such as shifting chairs, bodies, and papers. Carpet
is great at quieting these noises.
Be sure you know the reasons why you want to change carpet before
doing so. This will help you select the best solution for your
situation. Remember, any change in the acoustics load will appear
in the voice of the room. Carpet has lots of fibers which present
acoustic friction. Removing carpet changes the amount of acoustic
friction in the room, which changes the reverberation of the room.
Our sound technician keeps complaining about
echoes and feedback and always tries to fix them by buying new
speakers and microphones and moving everything around, but the
problem is never completely fixed. Is he doing something wrong?
This is exactly what people always try first. They generally exhaust
themselves dealing with this very issue. They buy more and more
electronic equipment without ever getting the improvement they
need until they're finally ready to give up on the allure of electronics,
sit down, and listen and learn about the world of acoustics.
Acoustics is a whole world, invisible to the eye, but very audible
to the ear. Once the sound is launched in the air, only acoustics
can help guide it to where it is supposed to go. That's what we
do at ASC. We take over where the electronics leave off. Here
is how we work: we get photos, floor plans, elevations, descriptions
of the problem, and often times audio recordings from you. Then
we estimate the probable cost for the "fix" for your
particular situation. Now you have a budget to talk about. Once
you decide that your ready to start working to fix the problem,
we analyze the problem in detail, design and build the solution
and you install it. You get to skip the middle man by purchasing
the proper solution direct from the factory.
We can also work with your audio technician, train them to do
the testing we need to analyze the room, provide appropriate photos,
and conduct interviews. We do our homework before we invest any
time in working up a design. We have to know what the rules are
within the church so we can work within those guidelines.
To answer some of your specific concerns, you should know that
it is the echoes that create feedback. Sound technicians are always
fighting "gain before feedback". Improving the on-stage
acoustics is one way to improve this. Eliminating echoes also
helps to improve the mic problems. Of course, it is always a good
idea to first check to make sure the sound system is set up properly
and not aimed directly at the microphones. Beyond this, it is
the acoustics that can make the necessary improvements.
My church is undergoing an interior restoration/rennovation
project. There are many things we are considering in our endeavor,
but the one major object involves the placement of our church
organ and choir. I have heard that the best acoustical position
for the organ is on the main axis of the church. Can you confirm
this or shed some light on this theory? What would be the best
acoustical positions for the choir and organ?
First, it's important to note that the physical location of the
organ keyboard is one thing and the locations of the pipes or
speakers is another. The type of organ or keyboard can make a
difference as to where to best place it.
An organ is typically played in a reverberant space. Organ music
is written so that the reverberation left over from the prior
note mixes with the sound of the next note to form a chord. It
is important to protect the reverberant part of the sanctuary
for the sake of the organ. The organ is usually located in a position
that easily and loudly stimulates the reverberation of the hall
in which it is located. If you move the organ, you change the
relationship between the sound generated by the organ and the
reverberation of the hall. The ceiling often has impact on how
the sound is stored and diffused throughout the space. If you
move the organ, it will change how the sound is fed to the ceiling,
changing the way it sounds in the hall. Organs are often located
along the centerline of a church so that they can stimulate as
much reverberation in the room as possible.
It's a good idea to contact the organ manufacturer or installer
before moving the organ. They usually have a lot of experience
matching the organ to the hall.
Everything pertaining to the organ also applies to the choir.
Except that the choir must also be able to hear themselves. Placing
the choir in a gallery allows some of the sound to be held within
the gallery. The choir sound heard by the congregation is "pre-blended"
by the walls, ceiling, and floor of the gallery. This makes their
sound sweeter, more full, and almost larger than life. The people
in the choir can hear themselves and each other because they are
essentially singing in a room that happens to have a large door
(the opening to the rest of the church). Choir members who can
hear themselves and each other better stay in tune and on tempo
better.
If you move the choir too far out into the open they struggle
against the thinness of their sound. However, there are some churches
who tire of the old world sounds of worship. The reverberant organ
and choir may no longer be a valued part of their service. Perhaps
the organ is being moved forward to join a contemporary praise
band. Likewise, the choir may be being turned into the backup
vocalists for the lead voices in the band. In this case, gut the
old gallery, turn it into a spotlight deck and get on with the
show. But, be aware that now their is a whole new issue of acoustics
to deal with: the interaction of amplified sound within your reverberant
hall. (See FAQ above.)
We are building a new sanctuary and we're
trying to decide between flat or vaulted ceiling. Which would
be better for the acoustics?
A shallow vaulted ceiling is better than a flat ceiling. Most
churches build their vaults running front to back so that there
is a high wall section at the front. However, a shallow vaulted
ceiling actually sounds better if the vault runs side to side.
This is because the sound is stored in the high volume part of
the space, which is located under the peak of the vault. So, the
sound is stored side to side in the area where the people sit.
Furthermore, people's ears are separated sideways so we are more
sensitive to side to side sounds. People tend to like the spacious
effect of side to side sound storage. A slightly sloped ceiling
at the front of the church moves sound away from the front towards
the congregation, keeping the launched sound clear and unmuddled.
A slightly sloped ceiling towards the back of the seating area
compresses the sound coming from the front making it louder for
people sitting further away, which is good, too.
A slightly sloped ceiling still keeps the sound of congregational
singing within the congregation, where it belongs, just like a
flat ceiling does, which is good.
Flat ceilings are not good, though. All sounds that hit the flat
ceiling are reflected back down to the floor at the same time.
The timing for floor-ceiling reflections is the same everywhere
in the church. This creates a horrible droning tone problem.
Remember that, no matter whether you build your church with flat
ceiling or sloped ceiling, or which direction you aim your vault,
you will still need to address the acoustics of the space. This
means you will typically need ASC acoustical treatment on the
back wall and on the side walls.
The front of the church is usually built with a raised stage that
is carpeted. You'll want to make sure the stage is quieted from
drumming and thudding sounds by building it with ASC WallDamp
between the joints and filling the cavity under the stage with
ASC SonicSnow. The front of most churches can be left fairly reflective.
Choir areas need proper design. Don't put them out in the open,
they need reflections returned to them so they can hear themselves
and stay in tune. Don't use carpet under the piano or choir. Carpet
the speaking area and, if there is a praise band, you'll need
additional ASC acoustics to get the loudness under control and
to get the mics working right.
Use one central cluster for speech and two side mains for music.
Only the soloist should sing through the central cluster.
Things always work best if you design the church from the beginning
around the acoustics. After all, if people can't hear what's being
said, they stop coming.
