Acoustic Sciences Corporation
APPLIED ACOUSTICS – RESEARCH, DESIGN & DEVELOPMENT
Acoustic Sciences Corporation has been providing solutions to acoustic problems in churches, schools, commercial facilities, recording studios and homes since 1984. Our work has led us to the development of methods now tested and proven for improving church acoustics.
Our architectural acoustic grids mount easily to walls and ceilings. The grids are aligned to develop an acoustic control system which promotes intelligibility, without sacrificing brightness, in your facility.
Intelligibility grids can be developed for sanctuaries, fellowship halls, classrooms, daycare rooms, cry rooms and offices. Although the applications may vary, the result is consistent: architectural grid patterns that sound as good as they look.
Acoustic Sciences Corporation offers free analysis, design, quotations and samples to accompany the quotes. To learn more about how proper room acoustics can benefit your church, call us at (800)272-8823 (9 A.M. to 5 P.M. Pacific Time). We look forward to your call.
Arthur M. Noxon, President Acoustic Sciences Corporation
FELLOWSHIP HALL ACOUSTICS
The expression “Church Acoustics” is almost always taken as a synonym for “Sanctuary Acoustics”. This shouldn’t be, when really there are any number of rooms in a church building that need to have proper acoustic balance to be usable by the church community.
The second most significant space in the church is the fellowship hall. This multipurpose room is the busiest of all spaces with its weekly schedule of committee meetings, socials, bible studies, receptions, and even morning Jazzercise workouts. The fellowship hall is also able to provide income for the church because there is often an attached kitchen and group meeting facility. By having a functional meeting room, the opportunity to extend its availability into the community becomes real. Of course that has financial impact, but also there is much to be said about providing the proper facility for the non-churched or un-saved in the local community.
There are typically 3 different configurations for fellowship hall use.
1) as a meeting hall for general fellowship where there are a number of tables set out.
2) for speaker to audience use as in a bible hour where only one person is speaking at a time usually from the front of the room and
3) for conference type purposes-Typically committee or board meetings where there are usually four or more long tables arranged in an open square. I’ll go into more detail on these different uses a little later.
All these, however, have a single powerful common denominator- People talking to people. Moreover, people understanding people. The only factor that blocks this communication from being completely successful and understandable is bad room acoustics, more accurately, a loss of intelligibility resulting from the interference by the architecture of the room. Under most circumstances the sound or speech is plenty loud, which means a PA or sound system is not the solution. Good intelligibility stems from good acoustics, not louder sound. It’s all to often just that simple.
THE MULTI-PURPOSE ROOM
Let’s take a brief look at the first typical configuration/use of a fellowship hall- as a general meeting place. As a meeting hall the seating arrangement is usually configured around any number of tables seating anywhere from 4 to 8 people per table. Generally there is a lot of talking going on and multiple conversations taking place. In reverberant rooms with numerous people talking, the sound-floor builds up with people talking louder and louder trying to cut through the noise of other conversations. Of course this is a self-defeating cycle that often leaves one with a feeling of anxiety or frustration. I’d like to make a note here that this feeling is amplified ten-fold for the hearing impaired. We become much more sensitive as our hearing goes.
The design of most fellowship halls is for economy and hygiene. There most common feature is that there is very little acoustic material around and it is a relatively low ceiling, wide space. i.e.- a rectangular room with a low sheet-rocked ceiling and sheet-rock or building block walls, and a tile or thin commercial carpeted floor. But in use, the acoustic needs of the people also become apparent and begin to be realized as well. The problem stands as a room that has already been built, and either a retrofit acoustic system or a complete contractor remodel of the room can change its acoustic properties.
The second typical use for the fellowship hall is as a lecture, presentation, or teaching hall where a single speaker addresses an audience. One person can talk and be understood by others in a reverberant space only if the speaker speaks slowly and enunciates clearly. But in fellowship halls there are often speakers who have not been formally trained who are conducting and participating in group activities. Generally they are not used to compensating for poor room acoustics and as a result the activities become handicapped by a loss of intelligibility. People in the audience who can not hear or who have to work to hard to understand what’s being said, grow restless and inattentive. Good information is lost because the communication channel has to much interference on it.
The third typical use of a fellowship hall is as a conference room. In this situation, there is often a set-up where there are a number of long tables arranged in an open square or rectangle so all parties can see each other. Many times there are lots of different opinions being voiced and many new ideas being expressed. The bad acoustics in the
room add to the feeling of discomfort, a dissatisfaction with the process- a low grade, almost intangible level of frustration that can multiply with the length of time of the meeting. This feeling surfaces as the conversations evolve and can contribute to discord.
Another common use of fellowship hall facilities is as a day-care center during service or other church functions. Children make a lot of noise naturally and are even louder than normal in a “noisy” space. As their voices are magnified by echo or reverberation, because noise acts as a stimulant, the other children respond by raising their voices. When a few kids get loud, the others get loud too. This kind of reverberant noisy environment can hyper-stimulate children into a state that is difficult to control or resolve. A noisy day-care area also has a definite depleting effect on the attention span of children.
As any adult who has spent time in a day-care setting can attest, when there is too much noise, it is often difficult to hear when a child has a real problem. When one child raises his voice in response to being hit or having his fingers smashed, it becomes hard to identify or even recognize that there is an emergency because the level of noise is
already so loud that the emergency sounds are lost in the general “ruckus” of the room. So there is a safety factor involved also.
Beyond the care of the children, one must take a careful look at the sanity of the loving, caring adults who are graciously sacrificing their time and energy trying to regulate, with one degree of success or another, the general mayhem in the day-care setting. (For those of us who have been there, we know it’s not really a matter of control. It
really comes down to having organized mayhem or disorganized childarchy, which is first cousin to anarchy…) The point being that we must consider the environment of the teachers as well, since they are the ones who have to keep a cool head.
There is something about a bare or acoustically untreated room that responds very quickly to noise. There is a shock value to an empty, reverberant room in terms of loudness. In an acoustically treated space, it doesn’t get as loud as quickly. Sharp, acute sounds aren’t as shocking, certainly you can hear the children but you’re not flinching
or being startled nearly as much. A lot of noise can be harsh and nerve-racking, much more so in a reverberant room. This feeling can breed impatience- and impatience and children mix about as well as oil and water. Also, the care-givers must raise their voices above the children’s voices in order to penetrate the wall of noise. This contributes to general fatigue and to diminishing tolerance as well.
As I had touched on before, another very practical consideration is that the population of the fellowship hall does include older folks as well as young. As we age, our hearing loses strength naturally and this loss greatly impacts the ability to separate someone’s speech from the broader spectrum of noise that surrounds us, In short, as we age we
lose our directional hearing sense. Even the best of today’s hearing aids don’t help this problem. Hearing aids only amplify sound and do not contribute to any directional capability at all. Good acoustic intelligibility does help the hearing handicapped hear better.
In choosing fellowship hall acoustics, two fundamental factors should be kept in mind. The sound of oneself and those immediately around them must be kept bright and lively, while the sounds from across the room must be attenuated. One might hope that the acoustic control of the walls would help out but it doesn’t. Wall panels or drapery deaden the reflection off the walls but again do nothing to reduce the sound moving across the room. Ceiling tile and carpet accomplish just the opposite, which is to deaden the local sound and yet allow the sound to
easily move across the room. The major pair of opposing surfaces in these rooms is the floor/ceiling. This is what stores the energy and causes the problems.
The acoustic control of wide low ceiling spaces is at first not obvious. The common proposal for treatment is adding acoustic tiles to the existing ceiling or remodeling and adding a dropped acoustic ceiling. All of these ceilings have one thing in common. Sound traveling up and down is more quickly damped out than sound traveling across the room. After ceiling tile is installed, the “sound” of the room does change, but the problem and the complaints persist. The next typical decision is to replace the lower cost ceiling tile with very expensive, fiberglass tiles which are very absorptive. At this point, the room “feels” very quiet but still when it’s being used by many people, the people on opposite sides of the room still hear each other too loudly. The problem has actually gotten worse while more money was being spent. At any rate these solutions are like painting over nail holes- white washing over the problem even though it’s still there!
The wrong solution to the right problem. Flat acoustic materials allow sound to travel easily across their surface without absorption while dampening sound that travels perpendicular to their surface- opposite of what we want to achieve which is to keep local sound lively and bright while absorbing the sound that travels across the room.
THE ACOUSTIC SOLUTION
So the room is built, completely finished, clean, well lit, and functioning-mechanically. The acoustic upgrade needs to be as unobtrusive as possible. We don’t want to have to replace all the lighting to fix the acoustics but that is what happens when acoustic tile ceilings are installed, nearly a full scale remodel in itself. Often, there are many windows in fellowship halls but we don’t want to cover the windows with office type wall panels. Carpet is often considered, but anything truly durable for the use of the room is acoustically negligible. The only remedy left is to dove tail an
acoustic grid into the existing ceiling. A grid that misses all the mechanical and electrical fittings and still does the proper job.
The Tube Trap surface is convex like a speed bump, and sound travelling across the surface hits the traps broadside and becomes quickly absorbed. The ASC Acoustic Coffered Ceiling gives the service that meets the specification. Local sound remains bright and lively, but sound from across the room is dramatically reduced. And this while the
coffered grid is sized and positioned to a design pattern that actually compliments the existing ceiling mechanical’s, lighting and electronics within the fellowship hall.
The Coffered Ceiling was also designed to be a pleasing aesthetic addition to the area decor that lends itself to the feeling of warmth and comfort that should be created in a fellowship environment. It is also easy to install in one or two evenings-best of all- it works every bit as much as you should hope for.
(See Enclosed Coffered Ceiling Tech. Sheet)
President/Chief Engineer- Acoustic Sciences Corporation
Acoustic Sciences Corporation
CEILING MOUNTED ACOUSTIC GRIDS
This noise control system is designed to retrofit existing sheet rock or concrete ceilings. It processes existing noise in a selective manner which includes the principles of noise control and sound making and provides a most agreeable acoustic environment.
The acoustic grid converts inhospitable spaces into comfortable settings, appropriate for conversation. Applications include any wide relatively low and hard surfaced ceiling that is above a floor space dedicated to multiple, simultaneous conversations. Open office plans, restaurants and fellowship halls are ideal candidates for the acoustic
Locally Lively Distance Dead
A bright ceiling reinforces An absorptive ceiling reduces nearby conversations. noise from sounds afar.
With the open grid, strips of absorption are positioned away from each other. This allows local reflecting sound to remain bright and lively. Sound from across the room engages the grid at a low angle of incidence and sees a nearly 100% absorptive ceiling. Local, familiar sounds are left lively and the existing nearfield sound masking effects are
allowed to remain in place. In high contrast, those long ranging sounds will experience aggressive attenuation by the same ceiling grid. The combination results in a natural sounding, local space with a sense of zonal acoustic privacy regardless of where one goes in the room.
By using our patented, surface mount grid system, the undesirable downtime and cost associated with the installation of a dropped acoustic ceiling is avoided. The grid is easily sized and arranged to avoid existing Lighting, Electricals, HVAC, Security, Sound, Fire, Fans and any other ceiling mounted equipment. Only one contractor not a half dozen need be on site to install this grid system.
Acoustic grid ceiling patterns can be designed for a variety of architectural applications. By aligning the grid all in one direction, sound is allowed to easily pass along the alignment but is highly attenuated across the grid. The result is a directional acoustic space that is suitable for a classroom or training hall. The side to side audience noise is suppressed while the front to back lecturer sound is reinforced by the ceiling reflections. By setting up a crisscross
pattern, the grid becomes equally effective in any direction, appropriate to the open office plan and other general use spaces.
The architectural acoustic ceiling grid system opens up many new options for the use of hard ceiling rooms. The features of intelligibility, zonal privacy and directional acoustics are readily developed by the proper alignment of this surface-mounted, acoustic grid system.
Acoustic Sciences Corporation
MULTIPURPOSE CHURCH HALL
This large hall is intended to be multipurpose, ranging from gym to congregational use. The hall needs general purpose noise control for its gym use. It also needs intelligibility for the understanding of speech in service and staged activities. This dual requirement for noise control and intelligibility has been met by one simple and
unobtrusive acoustic treatment, documented in this report.
The hall was constructed with least cost in mind and has a concrete/rubber floor with sheet rock walls. The ceiling is sheet rock suspended by 4 foot deep laminated beams on 1 2 foot centers, necessary to span the width of 62 feet. The hall length is 1 20 feet.
The natural bare reverb time (RT-60) is about 4 seconds. Too long for minimal acceptable (2 1/2 seconds) gym use and impossible for typical (1 1/4 seconds) speech. Cost is a factor in all projects. If it costs $2.50/ft-2 to cut reverb from 5 to 2 1/2 seconds it will cost an additional $5/ft-2 to cut reverb from 2 1/2 to 1 1/4 seconds. The RT-60
spec (1 1/4 seconds) for speech could not be met within budget for this facility. An alternative approach to the RT-60 version of the intelligibility spec was necessary.
Intelligibility is not a direct function of RT-60. It is based on the signal to noise” ratio and inside of this, reverberation contributes to the noise floor. This hall was outfitted with a noise control package that gave it an RT-60 of 2 1/4 seconds, acceptable for gym use. However, the acoustic devices were particularly arranged to provide a
strong adjustment of the signal to reverb floor noise levels.
By aligning the acoustic treatment to be very efficient at absorbing the early expanding wavefront, a sizable amount of energy is removed from the hall prior to the wavefront becoming evenly distributed in a uniform diffuse sound field. The results show in these balloon burst tests. The RT-60 is changed from 3 3/4 sec to 2 1/4 sec but the
absolute sound level that the reverb begins its decay is a full 6 dB below the untreated reverb levels. Dramatic improvement in signal to noise ratio has been achieved with minimal changes in RT-60.
This technique of aggressive damping of the off axis components of the expanding wavefront serves to strongly reduce the onset level of reverb following the direct signal, hence improving signal to noise and intelligibility. Here, the laminated beams were utilized as sound collecting horns. The resulting corner loaded acoustics attains 200%
acoustic efficiency even as low as 200 Hz. Although the hall remains semi-reverberant it now posses a distinct clarity for speech. Both the contractor and congregation remain happy to this day with the project.
(The above material was published by the Acoustic Sciences Corporation of Eugune, OR)
Christian Information Services