Acoustics in the Worship Space XII

February 27, 2020

Scott R. Riedel is president of Scott R. Riedel & Associates, Ltd., an acoustical and organ consulting firm based in Milwaukee, Wisconsin.

Editor’s note: Acoustics in the Worship Space, Parts I, II, III, IV, V, VI, VII, VIII, IX, X, and XI have appeared in The Diapason, May 1983, May 1984, January 1986, May 1987, April 1988, April 1990, July 1991, May 1992, April 2009, December 2012, and June 2015 respectively.

The times certainly have been changing, and continue to do so, relative to worship and music styles, practices, and church architecture. While this has always been true, the pace and intensity of change seem to increase as time goes by. Some years ago, a proper worship space was presumed to have pews along a center aisle, a prominent reredos with an altar or communion table at the end of the room’s long axis, and a music program using an organ as its primary instrument. It is not uncommon today to find alternative seating arrangements and to find video screens to be prominent visual elements in a room. Similarly, various musical styles, from traditional to contemporary, may be offered—some with and some without organs.

If a congregation uses both contemporary and traditional music, the architectural acoustic need is often to find a way to support and enhance the diverse musical styles. The challenge is that the differing musical styles may have significantly different room acoustic requirements and design responses.

The traditional musical forms benefit from generous reverberation periods and from generally hard, sound-reflective and sound-diffusing architectural surfaces and finishes. In traditional and classic sacred music, a reverberant and sound-supportive acoustical environment is both expected and used by composers and musicians as part of their musical expression. Further, the participation by the congregation in hymns, psalms, and sung or spoken parts of the liturgy is enhanced and facilitated by a reverberant, sound-supportive architectural environment that allows worshippers to hear each other; this is the essence of traditional hymnody and participation in liturgy.

The contemporary musical forms benefit from lower reverberation periods and from appropriate amounts of “soft” sound-absorbing architectural materials. In contemporary music, the use of electronic instruments, together with strong rhythmic drives and small vocal ensembles calls for electronically reinforced sound projection. The control of sound and musical production via an electronic system, together with a sound-absorptive and low-reverberance environment, is expected and used by songwriters and musicians as part of the idiom. Further, it is the higher intensity of sound from electronically amplified instruments and singers that leads the participation of the congregation. The full assembly’s hearing of each other together is not necessarily the essence of contemporary worship music.

There are two primary architectural approaches to meet the acoustic needs of differing worship and music styles. One is for a faith community to have separate spaces, each specifically designed for the holistic worship and music requirements of the varying styles. Many congregations adopt this approach. Typically, the “traditional” worship room is designed in a more classic architectural manner, with a generous reverberation period and a naturally “live” room-acoustic space. The alternate and separate “contemporary” worship room has a more casual architectural mood, with a lower reverberation period, and sound control and communication based on an audio/visual system. Having two separate spaces means that each room can be uniquely tailored to the worship style’s unique needs, and service times can be independently scheduled.

The other approach is for a congregation to have a single worship space in which different music styles are presented, either within the same service or at different service times. When a congregation desires to offer both contemporary and traditional musical forms within the same architectural space, it can be difficult to meet the acoustic needs of both. Amounts and locations of space for musicians, proximities, and reverberation period needs are different. These can be challenging to accommodate within the same room. The danger is that in the effort to meet the needs of multiple styles, the result might be that no style is served well.

How can a single room meet the requirements of multiple worship and music forms? How can the room and its acoustic environment benefit one style, without being a detriment to the other?

The essential laws of physics and acoustical science are fully in force and apply no matter what musical forms are used. These unchanging laws include the influence of a room’s geometric form and cubic air volume on sound behavior; generous space without sound-obstructing or sound-trapping features will facilitate good sound distribution. The location of musicians and sound sources both relative to each other and to the listeners will facilitate good tonal blend and balanced listener perception. The correct ratio of sound-reflective to sound-absorbing materials will establish an appropriate and functional reverberation period.

Fortunately, there are methodologies and means of changing acoustic environments within a single space to accommodate various stylistic needs. The reverberation period and associated sound-absorbing/sound-reflecting material ratios and locations are among the primary factors that affect traditional and contemporary music support and enhancement. A technique used to accommodate a broad range of musical styles within a single space is to provide a means of altering the reverberation period by changing the sound-absorbing/reflecting material ratios, amounts, and locations. An alterable reverberation period can be accomplished with such elements as movable draperies, fabrics, panels, or enclosures that can be repositioned, opened or closed. The reverberation period can be “tuned” for the desired musical style; to shorten reverberation time, greater amounts of sound-absorbing materials can be revealed in the room for contemporary music. To lengthen reverberation time, greater amounts of sound-reflective materials can be revealed in the room for traditional music.

The amount (surface area) and location of alterable sound-reflecting or absorbing materials relative to reverberation time in a room is a function of such factors as the size, geometric form, layout, and seating capacity/occupancy of the room. The methodology for altering the amount of sound-absorbing or reflective material in a space can be from as “low tech” as revealing or retracting fabrics/draperies or opening and closing sound-absorbing or reflecting panels, to as “high tech” as employing a series of pre-programmed motorized panels, fabrics, or drapery systems that can be shifted from absorbing to reflecting by the touch of a switch.

The cubic air volume of a room also affects the reverberation period and sound perception. In general, rooms with greater cubic air volume will have a longer reverberation period, and rooms with lesser cubic air volume will have a shorter reverberation period. The design and presence of a “resonance chamber” can be used as an acoustic environment-altering tool. The “chamber” is essentially a separate adjoining room or cavity of generous size that can be opened to the main space, thereby increasing the total cubic air volume of the room, or the chamber can be closed off from the main space, thus reducing the total cubic air volume. The combination of alterable sound-reflective or absorbing interior finish materials, along with the ability to increase or decrease the cubic air volume of an environment can facilitate the enhancement of various worship and music styles to an amazing degree.

It should be noted that, depending on the overall size and seating capacity of a worship space, the size and amount of changeable sound-absorbing/reflective materials, surfaces, fabrics, panels, and air-volume resonance chambers can be potentially significant. The ultimate benefit is that different worship and musical styles can be well accommodated within a single worship space through the use of flexible and alterable-finish materials and technologies, thus providing an excellent worship experience for all.

The accompanying photos depict some example worship and performance settings with alterable-acoustic features:

1. Movable sound-reflective drapery vs. sound-reflective and diffusing walls, Moorings Presbyterian Church, Naples, Florida:

a. sound-reflective and diffusing wall with velour drapery retracted;

b. sound-absorbing wall with velour drapery revealed.

2. Movable sound-reflective curtain vs. sound-reflective and diffusing walls, Vero Beach Community Church, Vero Beach, Florida:

a. sound-reflective and diffusing wall with velour drapery retracted;

b. sound-absorbing wall with velour drapery revealed.

3. Alterable/convertible RealAcoustix panels at the Shari Fleming Center for the Arts, Tabor College, Hillsboro, Kansas:

a. sound-absorbing wall panels revealed at all side and rear walls;

b. sound-reflective and diffusing wall panels revealed at side/rear wall near elevated seating, with sound-absorbing wall panels revealed at forward taller side wall.

(Photos and products courtesy of RealAcoustix, LLC, 2437 Rulon White Boulevard, #8, Ogden, Utah 84404.)

4. An interesting description of a resonance chamber design can be found on the website of the Morton H. Meyerson Symphony Center, Dallas, Texas:, then click on “About the Venue,” then “The Concert Hall” to find the “Acoustical Features” section.

Photo caption: Shari Fleming Center for the Arts, sound reflective and diffusing wall panels revealed at side/rear wall near elevated seating, with sound absorbing wall panels revealed at forward taller side wall (photo credit: Richard Lenz)

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