O'Fallon, Illinois

Acoustical Considerations for St. Clare of Assisi's New Church (Part II)

March 27, 2009

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DENNIS FLEISHER

This is Part II of a 2-part article.  Read Part I.

Sound reinforcement is always a concern in church design, particularly in the many larger Catholic churches that have been designed in the past 10 – 20 years. At St. Clare, the design factors called for the active involvement of the architect, acoustician, and parish members on many levels, but many of the design challenges were a result of liturgical priorities. This concept is worth exploring here, because St. Clare Church exemplifies many aspects of the design motivations and responses involved in the design of liturgical spaces.

The common wisdom, in acoustics and sound reinforcement for liturgical space, is that the building is to be designed for a resounding, uplifting acoustical character to support musicView of integrated speakers. and encourage the assembly’s participation in sung and spoken responses. This is a liturgical imperative. It is well known, however, that speech intelligibility can be difficult in such an environment. The solution to this acoustical conundrum is the sound reinforcement system, which must provide enough speech clarity (a certain “excess” level of clarity, in fact) to overcome the speech-blurring effects of generous reverberance, even for those with moderate hearing limitations.  Supplemental systems known as assistive listening systems or ALS must be used, even in less reverberant spaces, to provide intelligible speech for those with more severe hearing challenges.

Another liturgical factor was mentioned in Part I: the seating plan. With 1100 seats and the post-Vatican II priorities to keep members of the assembly within a reasonable distance of the altar (sixty-five feet is a commonly cited limit), the “central plan” becomes a virtual necessity. In the central-plan concept, the sanctuary platform is surrounded, at least in part, by assembly seating. Presiders and lectors in St. Clare address an assembly that, from their perspective, wraps around by well over 180 degrees. This means that no matter which way the presider is facing, many members of the assembly are off to one side or the other. These off-to-the-side assembly members receive less direct articulation from the presider and, therefore, less speech clarity. Again, a sound system is necessary to cover those seated to the presider’s side and, often, to the presider’s back.

In these specific regards, the acoustician has substantial challenges in addressing liturgical priorities. But, quite frankly, a Catholic church is a place for liturgy, and liturgical priorities must take precedence. This means that we acousticians do not design liturgical spaces for acoustics but, rather, that acoustics must find ways to serve the liturgical exigencies. In this specific case, St. Clare Catholic Church, a particular type of loudspeaker device, an active line-array speaker, was used to overcome the resounding acoustical quality provided by the architecture and volume of the space. An additional advantage of line arrays is their “form factor:” they have a small footprint (plan dimension) of about 6 inches square, though they are quite tall. The ones used in St. Clare were just over 9 feet tall. Through early collaboration with the architect, however, we developed a design strategy whereby the speakers were built into the two front columns of the church, concealed behind grille cloth. Though virtually unseen, these two nine-foot-tall speakers cover the entire 1100-seat assembly area.

A host of other design challenges arose over my five-year involvement with the parish of St. Clare, and each challenge was addresses openly and collaboratively. My collaborative efforts involved not only members of the professional design team, but also members of the parish, including the pastor, director of liturgy and music, the sound and music committee, building committee, and many others. On the professional team they included the architects, mechanical and electrical engineers, and liturgical design consultant. The new St. Clare Catholic Church is testament to the aspirations, commitments, dedication, and hard work of many individuals. It is also a testament to the values and virtues of collaboration and teamwork of all involved.

Photo credit: Dennis Fleisher

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

READ OTHER ARTICLES BY DENNIS FLEISHER:

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

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