How To Guides

Room Acoustics: Its Significance in Sacred Space and Liturgy

April 27, 2009


baptismal areaWhen considering acoustics for a new church or renovation, the sound system is often the first thing that comes to mind. A sound system is certainly important, particularly in churches with large seating capacities. The projection of intelligible speech to an assembly of 500, 1000, or more requires sound reinforcement in almost all cases. In Catholic liturgy, however, there are higher priorities for acoustics.  Our primary purpose in attending Mass is not to "hear" the word, though the Liturgy of the Word is certainly a central element of post-Vatican II worship. Only focusing on "hearing" the word proclaimed casts the assembly as spectators, a passive role that does not sufficiently honor the assembly’s involvement in liturgy. The sound of the assembly, the Body of Christ gathered for worship, truly matters in liturgical worship. Since those in the pews do not have the “benefit” of sound amplification to support their voices, a review of acoustics from a liturgical perspective can reveal its true significance in Catholic worship.

How Does a Sacred Space Sound?

The most important aspect of acoustics for Catholic worship is the sound of the worship space itself, independent of sound amplification. In architectural acoustics, this particular quality of a space is called room acoustics. (See Acoustics for Liturgy.) Virtually every architectural space has an acoustical quality, a sonic character that the room imparts to all sounds produced within it. Room acoustics is a critical design factor in all large assembly spaces, particularly in those wherein what is heard may at times be even more important than what is seen.

What the Documents Say – Why Room Acoustics Matters in Sacred Space

A review of acoustics based on liturgical priorities reveals that room acoustics is perhaps the single most important aspect of acoustics in Catholic worship. The subjective quality of room acoustics is most stereotypically characterized by reverberation, the lingering prolongation and enhancement of sound, manifest most profoundly and awesomely in huge, soaring, cathedral-like spaces. Acousticians have technical definitions for reverberation, as well as measurement standards and calculation techniques to quantify reverberation to tenths, even hundredths of a second. But those numbers have little meaning in terms of human perception, let alone the sensory experience of sound during liturgy. Moving beyond acoustics, physics, and numbers, let’s discuss the subjective aspects of reverberation and, more importantly, how they affect a body of people gathered for the celebration of liturgy and how they can impart an aura of sacredness to the church, i.e., both in terms of the building and the people.

Catholic Church documents have addressed the subjective aspects of sound and acoustics quite consistently in recent years. One of the earliest statements in a post-Vatican II document, Environment and Art in Catholic Worship (hereafter EACW), was expressed first as a requirement and then, in the same paragraph, as an exhortation, with an incisive statement of how a lack of reverberance affects liturgy and, more significantly, how sound affects what people do, how people interact in liturgy:

"Audibility of all (congregation and ministers) is another primary requirement. A space that does not require voice amplification is ideal. . . .

A room designed to deaden all sounds is doomed to kill liturgical participation." [EACW #51]

These same concepts are echoed and amplified in a more recent document by the U.S. Catholic Bishops, Built of Living Stones:

". . . Liturgical celebrations call for the clear transmission of the sung and spoken responses of the liturgical assembly, as well as of the words of the individual ministers such as the priest celebrant, the deacon, the readers, and the cantor and leader of song." [BLS #221]

". . . The sound-deadening tiles so vital to noise reduction in gymnasiums and other public buildings will be used rarely in a church and only with professional advice to reduce or eliminate outside noise." [BLS #222]

The attendant charge to the architect and design team is as follows:

". . . [T]hose chosen to design church buildings should be able to . . . [c]reate an environment by the use of space, sound, and visual aspects that will facilitate and encourage liturgical celebrations and the active participation of the faithful." [BLS #198; italics original)

More recently, the U.S. Bishops' Sing to the Lord (available as a PDF; see Documents from US Bishops' Committee on the Liturgy in Links to Church Documents) (hereafter STL) offers the following, first with regard to the acoustics of the building itself and, then, how that acoustical quality can either encourage or hinder the assembly’s participation:

Ambo"Acoustics refers to the quality of a space for sustaining sound, especially its generation, transmission, and reception. While individual ministers of the Liturgy, ensembles, and even choirs can be sound-enhanced through amplification methods, the only amplification of the singing assembly comes from the room itself. Given the primacy of the assembly’s song among all musical elements of the Liturgy, the acoustical properties of the worship space are critical. For this reason, specialists in acoustics should be consulted when building or modifying liturgical space." [STL #101]

"If each member of the assembly senses his or her voice joined to the entire community in a swell of collective sound, the acoustics are well suited to the purpose of a gathered community engaged in sung prayer. If, on the other hand, each person hears primarily only his or her own voice, the acoustics of the space are fundamentally deficient." [STL #102]

What the Documents Say – Design Factors for Room Acoustics

The preceding statements provide a conceptual foundation for room acoustics in liturgy, i.e., for the essential acoustical qualities created by the architectural space, infusing the environment with an audible aura of community that invites and encourages the assembly’s participation. This is very different from the acoustical criteria for most other large assembly spaces. What, then, are the appropriate design factors for creating this sonic environment and facilitating good liturgy through the sense of sound?

According to Built of Living of Stones,

altar"The first consideration in providing quality sound transmission is the acoustic design of the building. The interior surfaces such as the walls, the floor, and the ceiling affect the transmission of sound, as do design features like the ceiling height, the shape and construction of rooms, and the mechanical systems such as heating and cooling units and lighting fixtures. The sound-deadening tiles so vital to noise reduction in gymnasiums and other public buildings will be used rarely in a church and only with professional advice to reduce or eliminate outside noise. Soft surfaces such as carpets, rugs, and large fabric wall hangings absorb sound, while hard surfaces such as stone, tile, glass, and metals reflect it. A combination of sound-absorbing and sound-reflecting surfaces properly applied and used in correct proportion provides the kind of system needed for a worship space." [BLS #222]

As clear as these statements may seem initially, their implications for the design of liturgical spaces often unearth challenges and contradictions. Foremost is the well-known disparity between acoustics for speech and acoustics for music. The spoken word is generally more intelligible in a relatively “dry” acoustical environment (i.e., a space with short reverberation), while music sounds richer and fuller in a livelier, more reverberant environment. Indeed, the acoustical requirements for speech and music, at the extremes, are very different and, in some regards, contradictory.

The overarching priority, however, is that the liturgical space must serve both speech and music, including presiders, lectors, cantors, choirs, and assembly equitably (though perhaps not equally) insofar as possible. As a design strategy with regard to this particularly challenging aspect of acoustics, I recommend that neither priority be sacrificed for the other: speech clarity need not to be sacrificed for music; music need not be sacrificed for speech. Accomplishing this poses challenges in both design and execution, but it is an essential objective for a liturgical space that requires a collaborative effort between the architect and acoustician very early in the design process.

Sound-Absorbing Materials – The Pros, The Cons, The Dilemmas

ChairsMany of the most common questions that arise in church acoustics are related to sound-absorbing materials; a particularly perplexing one is the use of padded or unpadded pews. This actually involves at least three interconnected aspects of acoustics, and it highlights the special challenges in liturgical spaces as compared with other assembly space:

"This area [the congregation’s area, the nave] is not comparable to the audience’s space in a theater or public arena because in the liturgical assembly, there is no audience. Rather, the entire congregation acts." [BLS #51]

This is another intriguing aspect of liturgical acoustics, one that involves clearly disparate functions of seating areas. Unlike a concert hall or theater where the well-padded seats are intended, in part, to suppress audience noise, a liturgical space must support the sounds of those in the seating area. This suggests that padded pews are not only inappropriate, but conflict with liturgical priorities.

But what about the noise and distraction of fussy children or crying babies? Wouldn’t padded pews help mitigate those and other distracting noises? That question alone, even unanswered, reveals a conundrum: to pad or not to pad. When that particular question arises, another factor follows closely on its heels: padded theater seats help to mitigate differences in acoustics, particularly reverberation, for different conditions of occupancy. This is an important acoustical consideration in virtually all large assembly spaces, theaters, and churches alike. Note, however, that in a concert hall, the same padding that suppresses audience noise will also minimize the changes in acoustics with occupancy. That’s a good thing. In a liturgical space, padding the pews does reduce acoustical variations, but it does so at the expense of assembly support. That is not a good thing!

Although the padded pew question is often considered an acoustical decision, there are many competing priorities, including cost, maintenance, appearance, durability, etc. Nonetheless, the seating area is often the largest potential area of sound absorption in a church, and absorption in that particular region has both positive and negative attributes. It is important to weigh and discuss the inevitable trade-offs realizing that these trade-offs can be very different in large churches versus small churches or in churches with fine pipe organs compared to those with more contemporary, amplified music styles.

The Sound of Silence

tabernacleFinally, though the focus here has been on acoustics, on sound, we must not overlook the antithesis, the absence of sound, i.e., silence, as a key factor of church acoustics, one that imparts a very special element to the sensory environment of a sacred space, a prayerful sanctity, a quiet-as-a-church quality:

"Silence is the ground of all prayer. From contemplative silence emerge the sung and spoken prayer of the entire assembly and the prayers and proclamations of the various ministers." [BLS #221]

"Music arises out of silence and returns to silence. God is revealed both in the beauty of song and in the power of silence. The Sacred Liturgy has its rhythm of texts, actions, songs, and silence. Silence in the Liturgy allows the community to reflect on what it has heard and experienced, and to open its heart to the mystery celebrated. Ministers and pastoral musicians should take care that the rites unfold with the proper ebb and flow of sound and silence. The importance of silence in the Liturgy cannot be overemphasized." [STL #118]

In summary, room acoustics is a multifaceted element of the architectural design of sacred spaces, and it is a vital and integral part of virtually every moment of the Mass. From the loudest, most resounding "Alleluias" to the prayerful, sacred silences, it can deeply affect the experiences of every member of the assembly. Room acoustics is, indeed, a very precious attribute of the worship environment, and one of the many invisible elements that creates sacred space.

Dr. Dennis Fleisher earned a Ph.D. in Physics/Acoustics & Music from the University of Rochester/Eastman School of Music. He is principal of MuSonics, Grand Rapids, Michigan.


Acoustical Considerations for St. Clare of Assisi's New Church (Part I and Part II)
Acoustics for Liturgy
Church Acousticians and Their Role in Church Building and Renovation Projects (Part I and Part II)

Images from the Church of Saint Henry in Nashville, TN taken by Johan van Parys

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