There are two aspects to Church Acoustic
projects. One is the acoustic material to be used and the second
is the strategy for the application of this material. Our approach
when voicing the church is performance oriented. The church wants
to be bright yet clear sounding. This means we add as little acoustic
material as possible and carefully position it so as to best control
only the problem reflections.
In
a large hall, there are 3 areas of problem reflections: Front to
back; side to side; and floor to ceiling. In many cases, the floor
to ceiling sound is already being treated by a carpeted floor and
suspended ceiling, Tectum and batt, or other acoustic tile.
However, the bare walls allow unchecked
circulation side to side and front to back sounds. It is on these
areas that our work comes to focus. We do not apply general purpose,
mild mannered acoustics over all surfaces, but instead apply strong
acoustics located in special areas that particularly relate to the
sound emitted from the loudspeakers.
Our
first concern is the rear wall. Here we apply a tight pattern of
broad band acoustics blended with diffusion on the upper part of
the wall. This acts to simultaneously absorb and side scatter sound
reflections off the upper rear wall. Reflections off the lower rear
wall of course are returned, listened to, and absorbed by the congregation.
By this, we strongly reduce the return off the back wall of the
church that doesn't speak to the congregation but does feed the
buildup of the reverberant noise floor.
The
next area of concern is the front side walls. Sound up through the
middle octave of the piano keyboard expand away from the loudspeaker
equally in all directions. The resulting side to side echo and multiple
reflection problems must be treated. The back half of the side walls
need no treatment because the sound from the speakers reflects off
of them right into the absorptive rear wall. The lower half of the
side walls need no absorption because the downward wave is driven
into the floor and
congregation. Only the upper front quarter of the side walls need
treatment.
The
congregation prefers this voicing of the room because the speakers
no longer sound muddy, blurred and difficult to understand. The
strength of confusing echoes as well as the buildup of the reverb
field has been reduced. However, the room still sounds bright and
lively because sounds from the congregation are reflected back to
them, returned off the remaining bare sections of the walls.
The material we use for absorption
is very efficient throughout the vocal sound range. After all, it
is the sound of the voice that needs to be clearly transmitted from
the speaker to the congregation. Our approach to sound control for
churches is to reduce the strength of those early reflections that
do not contribute directly to the understanding of speech from the
loud speakers. In so doing, we reduce the built up strength of the
reverb field but not so much its decay rate, RT-60.
Reverb time is the measure of how fast
energy is removed from a room. We do increase the reverb rate because
we have added absorption into the room.
However,
our work is designed carefully to reduce the strength, the loudness
of the reverb field, and incidentally, the rate of the reverb decay.
This is the "signal-to-noise" approach to noise control
and it is consistent with intelligibility requirements. As a result,
we achieve clear sounding rooms that still retain their reverberant
signature. Both the Pastor's need for intelligibility and the music
director's need for a reverberant room can be satisfied at the same
time in the same space.
In
a large hall, there are 3 areas of problem reflections: Front to
back; side to side; and floor to ceiling. In many cases, the floor
to ceiling sound is already being treated by a carpeted floor and
suspended ceiling, Tectum and batt, or other acoustic tile. 
Our
first concern is the rear wall. Here we apply a tight pattern of
broad band acoustics blended with diffusion on the upper part of
the wall. This acts to simultaneously absorb and side scatter sound
reflections off the upper rear wall. Reflections off the lower rear
wall of course are returned, listened to, and absorbed by the congregation.
By this, we strongly reduce the return off the back wall of the
church that doesn't speak to the congregation but does feed the
buildup of the reverberant noise floor.
The
next area of concern is the front side walls. Sound up through the
middle octave of the piano keyboard expand away from the loudspeaker
equally in all directions. The resulting side to side echo and multiple
reflection problems must be treated. The back half of the side walls
need no treatment because the sound from the speakers reflects off
of them right into the absorptive rear wall. The lower half of the
side walls need no absorption because the downward wave is driven
into the floor and
The
congregation prefers this voicing of the room because the speakers
no longer sound muddy, blurred and difficult to understand. The
strength of confusing echoes as well as the buildup of the reverb
field has been reduced. However, the room still sounds bright and
lively because sounds from the congregation are reflected back to
them, returned off the remaining bare sections of the walls.
However,
our work is designed carefully to reduce the strength, the loudness
of the reverb field, and incidentally, the rate of the reverb decay.
This is the "signal-to-noise" approach to noise control
and it is consistent with intelligibility requirements. As a result,
we achieve clear sounding rooms that still retain their reverberant
signature. Both the Pastor's need for intelligibility and the music
director's need for a reverberant room can be satisfied at the same
time in the same space.