Volume 40, Issue 1 :: by Dawn Schuette
What are one’s expectations upon first entering a worship space? They vary according to one’s religious denomination, cultural values, experiences, and tastes. A few common elements, however, are powerful influences: the sense of space (intimate or grand); the aspect of light (its absence or control, with shafts of light from a concealed source or reference to the heavens, or from large openings that bathe a space in sunlight). But it is the aural experience — a hushed silence, a soaring reverberation, or an intimate voice — that can keenly reinforce the sense of the sacred.
Although sound is typically the sense that people find hardest to define, everyone reacts to the aural environment on an subconscious level. For example, a baby who makes a noise in a space that supports and allows her sound to soar will often stop, listen, and test the sound again, sometimes with even more enthusiasm! A quiet environment, with limited interaction, tends to quiet a child’s desire to call out or sing. This sense occurs in everyone, and the environment of a worship space will influence the way in which a congregation uses it. The music program, preaching style, and congregational participation evolve in response to each particular worship space.
For an architectural and acoustic design to be successful, it is vital that there be good, open communication between church members and the professionals who assist them in the design and construction of a new worship space or in the maintenance and development of an existing one. Clergy, music directors, and lay members of a congregation cannot assume that designers know their desires or understand how they worship. Designers need to hear the language of their clients to accurately interpret the needs of a particular congregation.
This article explores how people react to different sound conditions and how the impressions and emotions that sound evokes can be augmented or diminished by the construction and finishes of a worship space.
Defining Acoustic Quality
For any type of worship, there is general consensus that certain basic acoustic qualities provide the best aural environment. Without question, clarity is a key component of a successful worship space. Whether the space is a reverberant cathedral or an intimate chapel, the spoken word must be clearly understood, and the congregation must be able to participate fully in dialogue and song. Clarity is particularly important for music, but it also creates an engaging atmosphere for all worship activities; it welcomes and brings people into the community experience.
One’s ability to see strongly influences his ability to hear and both are critical factors for worship spaces, including the relationship of clergy to congregation, choir to congregation, and congregation members to each other. Direct line of sight is required for the initial sound to reach a listener, so the ability to see an altar or bema platform is a basic requirement for seating. Similarly, the relationship among congregation members is key to creating a good sense of community. The interaction of all participvants in worship was a major emphasis of the design for the Community of Christ Temple.
Aural response is also linked to visual or tangible impressions. For example, people may complain that they cannot hear well if they are in an environment that is either too hot or too cold, or if the seating is not comfortable. Conventional wisdom suggests that wood walls are necessary to provide good sound, yet many of the most revered worship spaces with excellent acoustics have little or no wood surfaces. The warm look of the material, and perhaps the fact that wood surfaces are often tangibly warmer than stone or plaster, contribute to this perception.
Finally, a space must be free of distracting noise from the exterior, from mechanical systems and noisy activities in adjacent rooms. Otherwise, speech and music must fight to be heard clearly above the noise.
People should not be intimidated by feeling that they do not know the correct, technical terms to describe sound. All can describe their impressions. Sound elicits strong emotional responses to a space. The following are just a few of the terms that I have heard from clients (and used myself) over the years.
Sense of “nakedness” or “being exposed”
These terms are often used when people feel they are singing or speaking alone, without support — the result of a space that does not support sound. In a worship space, such a feeling can cause people to hold back in speech or song. Three common factors in building design elicit this feeling. First, a space may be too dry and not provide support or blend for the sound. This does not mean that reverberation in a room must last for four seconds to be good. Reverberation does not have to be extremely long to be supportive, but it has to be strong enough and just long enough to allow the sound to develop fullness and richness.
A common problem is an excess of sound-absorptive finishes close to the congregation: wall treatments, curtains, plush seating, and carpet. Another issue less commonly considered is a lack of balance in the space’s frequency response: construction or finishes that remove either too much high-frequency sound or too much low-frequency sound. Either one can cause people to feel unsupported. Men’s voices will sound thin in a space lacking bass response. A space that does not support high frequencies may cause women with high voices to hold back. Conversely, a space described as “engaging” provides ample support and a balanced frequency response.
“Dry,” “dull,” or “dead” sound
Generally, the term “dry” describes a space with a relatively short reverberation time. The length of reverberation time that feels right depends on the worship style. A worship style based on speech probably wants only a relatively short reverberation time to provide the best clarity. One that includes chant or traditional organ music may need a long reverberation time for the proper development of the sound. In this latter case, I have heard people describe a room as dry when it has a two-second reverberation time.
“Live,” “full,” or “rich” sound
These descriptors apply to a space with a moderate or long reverberation time where sound “blooms,” or fills the space and envelops the participants. The emotional response is often quite powerful and uplifting to the spirit, bringing inspiration and a sense of excitement and grandeur. Such an acoustic condition is beyond the normal everyday experience, so it becomes a transformative aspect of the worship environment. Sufficient volume and the limited use of sound-absorptive materials are required to sustain sound for two seconds or more. The shape of the space is also important. A room with tall, nearly parallel sidewalls will sustain sound longer than an even taller space with a steep roof and lower sidewalls. The appropriate amount of volume and the proper use of materials will be determined by a number of factors: desired length of reverberation time, available height or building footprint, any existing limitations in construction (for existing spaces), room configuration (plan layout, balcony or not), and desired/expected finish characteristics. A congregation that chooses a significant amount of absorption in the form of padded chairs, carpet, and drapery should be aware that those materials have an impact on the sound quality. Length of reverberation is not the only factor in creating a full, rich sound. Strength of reverberation is also important. A small chapel may have limited volume, and with it a shorter reverberation time, but the shaping and finishes may be such that sound is sustained very efficiently and develops a richness and blend that can be quite pleasing.
Typically a “rich” and “enveloping” sound is well balanced. As noted earlier with regard to the sense of being exposed, people can sense on a subconscious level whether sound in a space is evenly supported at all frequencies. A sound that lacks low-frequency energy will be described as “weak.” Sound that overemphasizes high-frequency sound will be referred to as “harsh,” “brittle,” or “scratchy.” The common reaction to this characteristic is a sense of edginess or discomfort. Sound that lacks high frequencies will be considered “lifeless” and “dull.” A well balanced room response has neither too much high-frequency sound or excessive low-frequency sound. Construction materials must have enough mass to support bass energy appropriately for the room use, which in some cases will allow people to literally “feel” the music. Sound-absorptive materials should be limited or used carefully to avoid an excessive loss of high-frequency energy. This is particularly important for small rooms where a given amount of sound-absorptive material will have a larger impact than the same amount used in a large space. Surfaces must be well detailed to diffuse sound evenly and eliminate acoustic problems such as flutter (sound caught in a parallel geometry), which creates an edginess to the sound. Large, flat, parallel planes typically should be avoided.
Rarely can users define the desired reverberation time in their worship space. They know what they like or don’t like only when they hear it. It is therefore helpful for church members and designers to visit some existing spaces and to discuss the positive and negative aspects of those rooms before the design of a new space.
Generally there is less participation in an acoustically dry room, whether speech or music is amplified or not. People will not speak or sing out when they feel theirs is the only voice, or that their voice stands out above the rest. A dry room does not provide a sense of envelopment. The lack of reverberation time, however, is not always a bad thing. A dry space can be used to enhance contemplation. A small chapel or an individual worship or meditation area may benefit from the sense of serenity that comes from a quiet, acoustically dry environment.
An amplification system for speech alone or for music and speech must be carefully designed in a reverberant space to assure intelligibility. It is easy to excite the reverberant volume and to generate conditions that are muddy, so it is critical that the audio system deliver as much sound as possible directly to the listeners and not upward into the space.
“Distant,” “mushy,” “hard-to-hear” versus “articulation,” “transparency,” “intimacy”
These terms are typically used with regard to the clarity and the presence of sound. Members of a congregation may not realize that this is the issue at hand, particularly when describing the sound of an existing space. A chaotic or unclear environment is distracting and tiring for listeners, and makes it hard for the congregants to find their place in a text or to sing along with a hymn. At worst, people may “tune out” entirely. Those with hearing problems strain in a space without clarity. Good clarity allows one to feel that she is having a private conversation with the person speaking, or is sitting close to a singer or instrumentalist. This acoustic intimacy engages people.
Strong, late reflections of sound create echoes. Such reflections result from wide sidewalls, high ceilings, or distant rear walls. Timing differences do not have to be great to create a significant echo; strong reflections arriving just 1/20th of a second after the initial sound will make confusing echoes for speech. Interestingly, when people use the term “dead spot,” they are often referring to an echo rather than to a lack of sound. The echo interferes so much with the direct sound and early reflections that it is as if that original sound is completely lost. Focusing conditions (typically, concave geometries) that concentrate sound, often lead to echoes, because resulting strong reflections may, at times, be stronger than the original sound. Examples of this are gently concave ceilings or curved or faceted rear walls that follow a concave seating layout. Echoes must be controlled if clarity is to prevail.
Excessive buildup of sound in a space can make it hard to distinguish direct sound from the reflections of the preceding sound. Conditions of flutter (sound trapped in a parallel or similarly repeating geometry) can distort sound and lead to excessive sound buildup.
Too often the design of an audio system does not suit the conditions of the space. Care must be taken not to fill a reverberant room with amplified sound energy, as noted earlier. Loudspeakers covering a choir area, or monitors for amplified instruments will often create echoes if their sound reflects off walls or ceilings and interferes with the main amplification system for the congregation.
Although it may seem counterintuitive, increasing the level of sound amplification can diminish the clarity of speech or music. The louder the amplification level, the more likely that the room volume will be “excited” by the sound. Reflections become stronger and may begin to interfere with or completely mask the direct sound from the loudspeakers.
It is important to note that providing clarity for non-amplified music and speech is important in a room with a long reverberation time. A large warehouse can have a long reverberation time, but without proper shaping of wall and ceiling surfaces, the sound of a choir or speaker in such a space would be chaotic, distant, and inarticulate.
Quiet, Peaceful, Calm Environments
People find that a quiet space is comfortable, contemplative, peaceful, calming. Such spaces are hard to find today, so they can be an especially powerful part of any worship service. A quiet environment is powerful emotionally because it allows greater dynamic range for music or speech. Musical nuance evokes emotions of joy, sadness, excitement, grandeur. An orator can generate powerful emotion with dramatic pauses and alternately quiet and boisterous phrases.
People are not always aware how much they strain to hear above a general din. Unwanted or unnecessary noise is at best distracting and at worst tiring and unsettling. It is hard for anyone to concentrate or hear clearly if the levels of background noise (HVAC equipment, lighting hum, roadway noise, rain) are too high and threaten to cover the sound of speech or music. Control of background noise is especially important for those with hearing impairments.
Translating Good Sound Quality into Design
With input from religious leaders, music directors, and congregation members, and through careful use of materials the design team can achieve its desired effects. The building committee must communicate well with the congregation and with the architects, acoustical designers, artists, liturgical consultants, and other design team members. Experiencing and contrasting facilities firsthand is a great way to establish the baseline acoustic goals, desires for level of finish, and architectural style that will best suit the congregation. As the design progresses, regular communication and feedback are essential. The architect and the design team must communicate regularly with the building committee, describing the design decisions and the impact of those decisions on acoustics.
The examples that follow describe practical solutions to some of the most common acoustic challenges in worship spaces.
More Reverb in an Existing Space
The congregation of The Riverside Church in New York City wanted to improve the reverberation time within the worship space. The space had a grand volume, but the dull sound did not match the visual impression. For an existing space like this, the primary concerns for reverberation are construction materials and room finishes. For Riverside, the major issue was that an acoustically absorptive material, Acoustolith, had been used in the original construction in 1931. This material looks like stone, but is porous and absorbs high-frequency sound. Rarely used now, Acoustilith was popular in the early days of amplified sound reinforcement as a means of controlling reverberation in a large space and improving the clarity of the spoken word. Its one advantage is that the material is fairly dense, so it is a good reflector of low-frequency sound.
The solution to Riverside’s problem was to seal the material. To do this without changing its appearance, tests of clear masonry sealers were conducted. Sealer application was a complex process, but the result was the full, reverberant sound that a listener would expect upon entering a space of this scale. Clarity of sound was maintained because modern loudspeaker systems have much better pattern control for use in reverberant rooms.
Accent on Clarity
The Church of the Epiphany, designed by Spillis Candela DMJM and completed just a few years ago in South Miami, Florida, is a large room of nearly one million cubic feet. We became involved in the project after the initial design and section of the room were determined. Although there was sufficient volume to provide a great acoustic condition for music, the main goal stated by the users was their desire for good speech clarity. The acoustic design goal was to provide a good, balanced sound for music while controlling echoes and excessive reverberation that might harm clarity of sound. Acoustically, the result is a space that is impressively live, with a supportive environment that deliberately stops short of cathedral-length reverberation. It is an excellent setting for the spectacular Ruffatti organ.
The church interior uses a large amount of glass. To assure a balanced sound for music, opaque surfaces within the room were made of heavy materials to support low-frequency reverberation. The end walls of the nave, apse, and transepts are precast concrete. Concrete on the roof deck also provides low-frequency reflection and ensures that the sounds of heavy rainstorms do not interrupt Mass. Precast panels at the lower sidewalls are slightly angled in section to direct the congregation’s sound downward, encouraging congregational singing while avoiding flutter. Wooden pews are without upholstery to further support an engaging acoustic environment for the congregation.
A modest amount of glass-fiber paneling was added to the room to avoid excessive reverberation and to minimize echoes. Panels are located on the underside of the pews and in a narrow band on the high ceilings at the extreme ends of the room. Panels were also integrated into the faces of the one-story structures behind the congregation, where they also provide echo control from the audio system.
The room includes separate voice and music reinforcement systems. Voice reinforcement uses two pairs of steerable array loudspeakers mounted to the base of the steel arch at the transepts. The loudspeakers near the pulpit and presider’s chair provide good directional realism for speech. A series of small cabinets mounted below the clerestories and aimed down at the pews provides music reinforcement. The loudspeakers are delayed and zoned to accommodate sources from the choir loft or the chancel. The voice reinforcement system provides excellent clarity.
Engaging Sound in a Contemplative Space
The Church of the Transfiguration in Orleans, Massachusetts, designed by William Rawn Associates, is a modern expression of an early Christian basilica. This form was selected as best suited to the monastic tradition and style of worship. Daily services, often sung in Gregorian chant are held for members of the religious community and the public. After visiting churches in Europe, the congregation leaders asked for a space with a soaring acoustic character but one that would also support quiet contemplation. The congregation rejected the use of amplification in the room for either speech or music.
The nave is a long, rectangular space with narrow side aisles whose height provides the desired long reverberation time for chant. The lower sidewalls, deeply sculpted with window recesses in the exterior wall, provide diffusion low in the space. The large entry doors at the rear wall incorporate sound absorptive materials behind a brass screen material to control echoes directly down the center aisle. Upper sidewalls are angled slightly at the band of the mosaic artwork and clerestory windows to mimic early architectural construction techniques of lightening the structure as the building rises. This construction provides natural flutter control and enhances the sustainment of sound in the upper volume.
Cast-in-place and precast concrete elements and grout-filled masonry comprise the enclosure of the room to provide full support of the non-amplified voice and organ. Stone and mosaics along the walls and apse ceiling are being added in phases and are directly applied to the concrete and masonry to assure a solid wall construction.
The apse is rounded in both plan and section at the altar. Shaping was incorporated into the lower bench that wraps the chancel to redirect the effect of the focusing geometry in the lower plane of the room. The curve of the ceiling at the chancel naturally enhances non-amplified speech and singing originating from the altar and the front of the room. The peaked roof of the nave is relatively shallow to support reverberation development in the upper volume of the space while preventing direct reflections from the high ceiling to the floor that would otherwise create echoes.
Background noise levels in the space are extremely low, which was not a small feat, given that the location of the air-handling fans and pumps had to be adjacent to the upper sidewall of the nave. Multiple layers of construction in the mechanical equipment room prevent direct transfer of vibration from the equipment to the nave structure. A series of shafts outside the space and tunnels below the nave floor provide sufficient distance to attenuate the sound of the fans and distribute air efficiently within the space.