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Acoustics in the Worship Space I
Scott R. Riedel

From the May 1983 Edition of The Diapason.

Acoustic in the Worship Space, I, II, III, IV, V, VI, VII, VIII, IX have appeared in The Diapason, May 1983, May 1984, January 1986, May 1987, April 1988, April 1990, July 1991 May 1992, and April 2009 respectively.

"Form Follows Function." This fundamental principle of architecture and design is familiar to many. When considering the design of a worship space, the application is simple; the function is worship, so the form must be an envelope to sustain that function. But is the principle really that simple, and is the principle really understood by architects, designers, and planning committees'? Let us consider the real function of the space. What do we do when we worship? Worship is primarily a function and an experience in sound. Producing and listening to sound in the form of speech and music are among the foremost activities of worship. Services of communion, preaching, song, prayer, confession, or any other occasion that touches the lives of God's people are all conducted on many levels—aural, visual, tactile, and olfactory. To be sure, the chief vehicle of communication in nearly every worship format is sound. Worship spaces, therefore, must be designed as living spaces for this aural experience, a silent place is exactly what a worship space is not. Certainly, periods of silence may punctuate and lend mood and drama to worship, but silence is a condition that can be created by inhabitants of a space. The worship space must be ready, waiting, and willing to enhance the sounds of worship.

The question for the designer is not, "Can one hear?", for any preacher, singer, choir, or instrument can be made audible, even if only by sheer volume and intensity of tone. The character, quality, unity, and spirit of tone is the key in a worship space.

We can review briefly some of the many participants and contributors to the worship experience to see the significance of sound quality to each of them.

The Listener
The ultimate goal of any acoustical environment is to deliver the desired quality of tone to the listener. In the worship space the listener has a dual function, for he or she is both sound receiver (listening to choir, instruments, reading, preaching) and sound source (in hymns, prayers, and responses). The listener desires clear, direct, full, intelligible. and encompassing tone, and must have the tone of his or her own voce reinforced and united with other listener-worshipers for enthusiastic corporate singing and response. All locations within the space must have equally good acoustical conditions, for there is no room for a second-rate seat in God's house. The listener, as with all characters in the drama of worship, must have an acoustical environment free of acoustical faults and unwanted noise.

William Sumner comments: "...it is a well known fact that an organ of indifferent quality will sound tolerable or even well in a resonant (reverberant) building, and that even a fine instrument will sound unimpressive and dull in unsuitable surroundings."[1]

This principle can be applied to any sound source in the worship space, whether it be speaker, preacher, singer, choir, organ, instrument, or congregation.

A friend of mine has confessed the "secret" of his own musical success, based upon listener perception in a superior acoustical environment:
"...repeatedly I hear ' has the finest music in our town,' 'no finer choir.' I am a very mediocre musical director with a very average choir, but of one thing I am, certain, it is the acoustics in our church!! In that building everything surpasses."

The Composer
Composers of sacred music in our day, as throughout history, have a certain expectation for the acoustical character of the worship space, and compose accordingly. Often a composer will dedicate his or her efforts toward a particular building or musical group and compose for specific conditions. Even when a particular space is not the object of the composition, the writer still expects and uses an appropriate acoustical condition in the worship room as a tool of composition, much in the same way that expectations about organ voicing, registration, and temperament are tools of composition. Surely, each composer knows that all spaces are not alike, and that his or her music will not always be heard in the most satisfactory setting. However, a certain standard of acceptability and excellence must be met to deliver the composer's vitally important contribution to worship effectively. A setting which projects clear and even tone to all locations, reinforces sound, and does not obscure subtle nuances is desired by composers. An appropriate reverberation time is also essential. Many composers have stated the importance of the acoustical setting to the composition and performance of music. Note these phrases:

"...consider the pause that follows the ornamented proclamation that opens the famous "Toccata in D Minor' (J.S. Bach). Obviously this is for the enjoyment of the notes as they remain suspended in air. In harmonic structure, Mendelssohn's organ music is tailored to ample acoustics, for the composer played frequently in the great spaces of St Paul's Cathedral in London. Franck's organ music, as that of Bach, frequently contains alternation of sound and silence, and depends for it's effects on a continuing acoustical trajectory of tone."[2]

"Of the series of canticle-settings offered to people and places this is the most extended in scale (Magnificat and Nunc Dimittis for St. Paul's Cathedral by Herbert Howells). With the great spaces of St. Paul's in mind, the nature of this setting would be acutely influenced. Prolonged 'echo' notable in St. Paul's would dictate a less rapidly-changing harmonic rhythm than would be feasible in many less-reverberant buildings. So it is that in the setting harmonic and tonality changes are deployed in more leisured, more Spacious ways. Climaxes are built more slowly. But with these conditions there goes a heightened volume of sound, and a tonal opulence commensurate with a vast church."[3]

Due to the present common interest in historical practices, be it organ building, musical performance, or other aspects of the musical art, a church or institution might consider investing in the recreation of not only instruments and practices, but also acoustical settings. This concept may be especially useful to congregations or institutions of strong ethnic heritage for the purpose of recreating a composer's or era's style.

The Performer
There is probably no successful performer or conductor working in any aspect of serious music that does not realize the impact of an acoustical setting on the performance of a piece. The success or failure of a career in music may in part be attributed to the tonal character of a room. Opera singers will regularly vie for the best position on a stage, giving advantage to their voice. The tempo, dynamic and style of a performance are often a function of the effect of the room. Ensemble, precision, unity, and tuning stability will all be aided by an acoustical setting that provides strong early reflections, even distribution of tone, and an appropriate reverberation period. Amateur groups especially will benefit from the enhancement of tone lent by the acoustical setting. Musical inadequacies may be covered by extended reverberation times.

The appropriate period of reverberation is essential to the success of any acoustical space and musical performance. Many performers of note have written on this subject.

"Reverberation is of great help to a violinist. As he goes from one note to another the previous note perseveres and he has the feeling that each note is surrounded by strength. If each successive note blends into the previous sound, it gives the violinist sound to work with. The resulting effect is very flattering. It is like walking with jet-assisted take-off."[4] - Isaac Stern

"An organist will take all the reverberation he is given, and then ask for a bit more, for ample reverberation is part of the organ music itself."[5] -F. Power Riggs

"...and you have to have a good instrument and good acoustics."[6] -Vladimir Horowitz

One more example can demonstrate the great influence of acoustics on musical performance. The associate conductor of the Milwaukee Symphony Orchestra, Paul Polivnick, has repeatedly commented how often further practice on a work becomes useless in a rehearsal hall, because the entire character of sound will change when musicians are placed in the acoustical environment of the concert hall.

The Speaker
A frequent challenge to the designer is the combination of speech and music in one acoustical environment, because speech and music are equally important vehicles of expression in worship the requirements of one must not be sacrificed for the other. Many acoustical goals are the same for speech and music; even distribution to all listeners, full tone, and absence of noise and faults. The length of reverberation time is an important issue that divides the two, for longer periods of reverberation necessary to give grace and beauty to sacred music may also diminish speech clarity and intelligibility. The spoken word, however, will gain power and authority in a reverberant setting, so the two are not as opposed as one may suppose. With careful design and modern technology it is possible to provide settings that are not merely acceptable, but are superior for both mediums of expression.

The existence of numerous worship spaces with exceedingly inferior acoustical characteristics shows a great misunderstanding of scientific principles and an insensitivity to the real activity of worship. Music suffers acutely in the name of speech clarity, when in reality neither music nor speech is given a desirable setting in many spaces. Often, absorbing materials are introduced which remove any and all desired sound energy and then in compensation organs are only passably voiced, choirs seldom sing in tune or ensemble, and large sums are spent on electronic equipment to increase the volume of the spoken word. In the end much money is spent, and the congregation gets no real benefit. All too often silence is the goal in a misguided conception of the nature of worship. The sounds of life are removed by "acoustical treatments" which simultaneously destroy the vitality and vehicle of aural expression. Surely, this is contrary to every noble ideal of unity and corporate activity in the praise of God. The "quiet" freedom from intruding noise should not be mistaken for silence from within the worship space itself. It should be noted that unexpected "noise" originating from those occupying the worship room is by definition 'noise" and "irritation level" - is generally not raised or lowered by the acoustical environment.

What then is the nature of a design and building fabric that is an appropriate envelope for the true function and activity of worship—a setting for speech and music? Four physical elements of design must be combined and manipulated to create an appropriate space. These elements are the shape, volume, and materials of the space, along with the placement of people, equipment, instruments and furnishings within, the space. The goal of the combination of these elements is a room where sound of all desired frequencies is evenly distributed to all appropriate locations, where sound energy is reinforced, not removed from the space. Reverberant sound must linger the appropriate length of time and then decay at an even rate across useful frequencies. Faults such as hot spots, echoes, dead spots, and intruding noise must be suppressed.

Room Shape
Basic room shape is the foundation of an acoustical setting. The overall shape of the room must be designed to achieve acoustical principles and goals, for, even when all other conditions are at the optimum, an inappropriate shape can cause nearly irreparable faults. Concave surfaces which can focus sound onto hot spots, walls, and objects which create obstructions and acoustical shadows, listening areas or secondary spaces removed from the sound sources by corners, alcoves and arches are all elements of inherent shape that can be detriment to a successful design. New designs must he conceived with overall shape and proportion sympathetic to acoustical needs. It is often expensive or impossible to repair acoustical faults in existing structures when basic shape and proportion are the cause of a problem.

Most often, these principles will promote a successful result:
1. The room should be higher than it is wide, with musicians and sound sources such as organ or choir placed at the end of the long axis,

2. Concave shapes which concentrate reflected sound should be avoided. Overall concave shapes may be acceptable if treated with convex or multifaceted surface configurations which can diffuse sound widely across the listening space.

3. Long, flat parallel surfaces should be splayed or interrupted with projections and fenestration to avoid flutter echo or standing waves (a condition of closely repeating echoes, or series of concentrated hot and dead spots due to multiple reflections).

4. All listeners and sound sources should be within the same basic room or space. Alcoves, archways, corners and objects which set apart any participants will obscure, confuse, and diminish the effectiveness of incident sound energy.

5. Echo may be avoided if sound energy reflected off of surfaces is directed to useful close locations, and not allowed to travel great distances. Absorbing materials should not generally be used to eliminate potential echo.

Room Volume
One key element in designing for a desirable reverberation period is the cubic volume of the space. A cubic volume near 500 cubic feet per listener seat is essential to reverberation periods appropriate to the worship space. A general rule is that a doubled ceiling height will double reverberation time. In rare modern instances too great a volume wilt cause a reverberation time so long that sound is muddled and lacks intelligibility. A minimum reverberation period appropriate to church music is two (2) seconds at mid-range frequencies.

Surface Materials
Surface materials and texture in the worship space must be such that incident sound is reflected, diffused, directed to desired locations, and allowed to reverberate. Any finish materials which absorb sound and remove sound energy from the space are counter-productive to the work of musicians, speakers, and worship participants. Absorbing materials which remove sound energy as a remedy for acoustical faults must be used as a last resort. Incident sound energy from worship participants is worthwhile, necessary, and should not be removed by absorption. Carpeting, drapery, acoustical ceiling and wall tiles, and other porous materials are all absorbers and must be avoided. The texture of cloth and material as art appropriate to worship in forms such as banners, vestments and flags can comfortably be included when all other conditions are suitable, so that acoustical quality will not suffer, Absorbing materials should not be part of the initial design of the building fabric. Materials such as plaster, stone, marble, sealed woods, quarry tile and other natural hard, dense, and reflective) materials can provide warmth of color and remain an aid to sound. Isolating materials arid assemblies within enclosing walls can be used to impede the intrusion of noise from adjoining spaces. It is essential that every interior material and construction assembly be carefully chosen and detailed, for the type of wood or brick, the interior assembly of a wall, even the manner of application of surface finishes, will all influence sound behavior across the entire range of frequencies. In existing rooms, it is often possible to resurface or otherwise alter materials to improve acoustical conditions.

Physical Placement
A successful worship-acoustical setting involves careful placement in all aspects and elements of design. From the overall concept of seating, to the precise location of each organ pipe, proximity and placement are important to acoustical goals. The site of a worship building must be chosen so that neighboring noises will not intrude and interrupt the worship proceedings. Noise producing areas of the building such as gymnasiums, or even heating, air-conditioning, and mechanical equipment must be located and detailed to prevent noise transmission to the worship area. Within the worship space all musical forces (choir, organ, organ console) must be located together so that musical unity, precision, and ensemble may be promoted. The best plan is one where choir singers are seated directly in front of the organ case, and the organ console is located in front of the choir singers. This allows sound to blend into unity, and gives all musicians direct and clear aural and visual connection. All seats in the worship space must have "line of sight" unobstructed access to the sound sources (clergy, speakers, and musical forces). If any location is around a corner, behind a column, or beneath a secondary ceiling, arch, or transept, even and clear sound will not be delivered to that location. Similarly, all worshipers should be in the same room, with no corners, columns or secondary spaces which separate in order to promote unity and community in worship, singing, and response.

A space which will give life and vitality to every medium of worship is the noble goal in creating places of prayer and praise. We can be lifted to unknown heights when the arts, music, architecture, science, and people join in common purpose.

1.Sumner, William Leslie, The Organ, its Evolution, Principles of Construction and Use (London: MacDonald & Co., Ltd., 1952).
2.Beranek. Leo L., Music, Acoustics & Architecture. (New York: John Wiley and Sons, Inc., 1962).
3.Howells, Herbert, Church Music , (London: Arto-Decca Record Co., ZRG 507),
4.Beranek, Leo L., op. cit.
5.Beranek, Leo L., op. cit.
6."An Informal conversation with Vladimir Horowitz" Ovation Magazine, March 1983.

Scott R. Riedel is President of Scott R. Riedel & Associates, Ltd., an Acoustical and Organ Consulting firm based in Milwaukee, Wisconsin

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