Thanks to a commentator on this blog, I was alerted to the existence of Reidel and Associates, a firm that does consulting on worship spaces. I ordered their pamphlet (why not post online?) about sound. It is called "Acoustics in the Worship Space" by Scott R. Riedel (St. Louis: Concordia Publishing House, 1986). It is quite technical and very informative. Here is what he says about floors on page 17.
The floor is typically the building surface that is largest and nearest to worshipers and musicians. It is important that the floor be reflective of sound, particularly near musicians, since it provides the first opportunity for much sound energy to be reinforced. Carpet is an inappropriate floor covering in the worship space; it is acoustically counterproductive to the needs of the worshipers. The mood of warmth and elegance that carpeting sometimes provides can also be provided with acoustically reflective flooring such as quarry tile or wood that is of warm color and high quality. The notion that the worshiper covers the floor surface, making its material composition acoustically unimportant is false. The large floor area of the worship space bas great acoustical influence. Appropriate floor materials include slate, quarry tile, sealed wood, brick, stone, ceramic tile, terrazzo, and marble.
Walk and Ceiling. Durable, bard-surfaced walls and ceiling are also essential for good acoustical reflections. The ceiling is potentially the largest uninterrupted surface and therefore should be used to reinforce tone. Large expanses of absorptive acoustical ceiling tile are to be strictly avoided. Appropriate wall or ceiling materials include hard plaster, drywall of substantial thickness, sealed woods, glazed brick, stone, med and painted concrete block, marble, and rigidly mounted wood paneling.
The construction of walls, floors, and doors should retard the transmission of noise into the space from adjoining rooms, from the outdoors, or via structure-borne paths. Sound attenuators or absorptive material may be fitted to heat and air ducts to reduce mechanical noise also.
Some may consider using absorbing materials such as carpeting or acoustical tile to suppress noise from the congregation. Noise from shuffled feet or small children is usually not as pervasive as might be feared. It is unwise to destroy the proper reverberant acoustical setting for worship in deference to highly infrequent noisy behavior.
Some absorbing materials may be necessary in a space to reduce excessive reverberation periods, to increase acoustical clarity, or to suppress unwanted reflections and faults. Absorbents should be used very sparingly and only when necessary.
