Acoustics, chamber music, and congregational song

Our parish recently hosted a chamber music festival, as mentioned in the previous essay. The church was filled to overflowing for three concerts of music. The first night was centered on the Quartet for the End of Time; the second featured the music of Webern and Schoenberg (“Verklärte Nacht”); the third consisted of an evocative Tenebrae by Osvaldo Golijov and Schubert's quartet “Death and the Maiden.” The musicians praised us as a venue for chamber music, especially in terms of acoustics. Most musicians find it rewarding to play or sing in the room, as do I.

Why?

Arthur H. Benade, in “Fundamentals of Musical Acoustics” (1976: Dover reprint 1990), comments: “Singers and instrumentalists enjoy performing in a reverberant environment.... Their confidence is heightened by such surroundings and so, as a matter of fact, is their accuracy in achieving the desired pitch relationships...” (p. 286). When the room has a sufficient reverberation time, the sound from a first note lingers long enough to overlap with a succeeding note. A musician unconsciously uses this overlap to gauge the intonation of the second note in relation to the first; it is as if the two notes were being played together rather than successively. The overlap need only be in the neighborhood of a half-second, though the longer the overlap, the better in terms of intonation.

On the other hand, in a really “large” acoustic with many seconds of reverberation, “there is an upper limit to the rapidity with which tones can follow one another and still show a relationship. This is because in rapid playing the remnants of several earlier tones may ... confuse the auditory picture.” It is not a problem for vocal polyphony of the Renaissance, which is thoroughly at home in such an acoustic. Nor is it a problem for a large part of the organ repertoire. The music of Franck and his successors in the French nineteenth and twentieth (and twenty-first) centuries is at its finest in such surroundings. Bach, Buxtehude, and Distler, on the other hand, are often less successful.

Reverberation time is traditionally related to room volume: large room, large acoustic. When architecture is honest, this relationship holds. But dishonesty is possible. The Chapel at Duke University is a fine neo-Gothic edifice, seating well over a thousand. It looks like a European cathedral. But for decades, it sounded more like a suburban living room. It felt dishonest as soon as one walked in the door; there were no echoing footsteps, no acoustical clues that this was a large space. The ceiling was covered with “Akoustolith,” a material that was used to mimic stonework and dry up the acoustic for the benefit of the clergy. The story is that Dirk Flentrop, a noted Dutch organbuilder who was contracted to build a new instrument for the Chapel, arrived from Europe in 1968, walked in the door, clapped his hands once, listened, said “This will not do,” walked out, and flew back to the Netherlands. (This essay glosses over the incident, which may be apocryphal, but describes the issues involved.) Flentrop would not build an organ unless the acoustics were improved. So, for almost a year, scaffolding worked its way through the Chapel as workers sprayed sealant over the “Akoustolith,” making it more reflective. I heard the room before and after, and the difference was remarkable; the reverberation time was increased from about three seconds to eight seconds. Once the acoustic matched the size of the room, Flentrop returned, built a fine instrument, and the Duke Chapel stands as one of the finest venues for music on a grand scale in the Southeast. Something like the “Resurrection” Symphony of Mahler or the Verdi Requiem would be magnificent in that room.

But it would not be a good place for a string quartet. In those days, the resident quartet played in the East Duke Music Room (now the Nelson Music Room), a fine old high-ceilinged room that seated about three hundred. Its reverberation time was around one or one-and-a-half seconds.

That happens to be about the same as our parish church. When empty, the reverberation time is around one second, and probably about two-thirds of that when full. For chamber music, this is ideal. There is sufficient reverberation for accurate pitch relationships, and the musicians can play or sing rapidly without fear of “outrunning” the room.

Congregational song is a form of “chamber music.” When we sing, we are a group of people who must listen to one another, and tune our voices to one another based on what we hear in a manner akin to a string quartet. In a large acoustic such as the Duke Chapel or the Basilica of Saint Louis, congregational singing is less successful than it is in a room such as our parish church. Even at the pace of a congregational hymn, the notes “outrun” the room, and it becomes difficult to maintain a rhythmic ensemble among people spread across the space. As a singer out in the nave, one hears plenty of sound, but it lacks coherence. “Drying up” the acoustics, as was done at Duke, does not help, for the people are still spread across a large space. In fact, it does not even help the clergy. Listening to a sermon in a large “dry” room is akin to listening to the radio. The sound is obviously artificial, disconnected from anything human. Even in the most resonant of rooms, a sound system which takes account for the precedence effect, first described by the physicist Joseph Henry in 1856 and which Benade outlines on pages 202-205, allows the preacher to be clearly understood and still perceived as a human being. But the preacher must speak speak slowly and distinctly – like the musicians, she must avoid “outrunning the room.”

A very large acoustic is less than ideal for congregational song. It is nonetheless better than the opposite extreme, often found in American churches: the dry room, swathed in carpet and padded pews – or nowadays, padded stadium seats with cupholders. In a dry acoustic, singers lose confidence. They cannot properly hear one another, or even their own voice. Churches with such an acoustic often compensate by having songleaders, equipped with microphones and backed by a “praise band.” The congregation can then sing along with the amplified music, each individual in relative aural isolation and subjugated to those “up front.” That is quite different from the community built by listening to one another as a congregation. The latter is more challenging, but more indicative of our standing in the Body of Christ. A room of appropriate size for chamber music proves to be a space which encourages such singing.

An abridged version of this essay appears in the August edition of our parish newsletter. For further study, I highly recommend Benade's book, alongside the classic text in the field of acoustics, “On the Sensations of Tone” by Hermann Helmholz (1877: Dover reprint 1954). Benade gives more attention to room acoustics and the construction of musical instruments, especially wind instruments; Helmholz more to the production and sensation of musical tone, especially the human voice and the physiology of hearing. His book is a primary source; in much of the book, he is writing of his own experiments and discoveries. In a footnote on page 273, Benade described Helmholz as one “whose name is as famous in acoustics as it is in optics, electromagnetism, and thermodynamics.” He was a pioneer in all of these areas, one of the great physicists of the nineteenth century.