Harmonics and Echoes

The choir finished out last note, holding it and fading away. But a different note continued, floating above us, at a perfect fifth above the altos. Large grins bloomed on the faces of those of us who realized what we’d done. We’d been so in tune, and so intense, that we’d raised a harmonic from the chancel that echoed back into the nave (where we were sitting). There’s a reason I prefer singing from the nave than from the chancel in this particular space!

A description of the setting is, perhaps, in order. We were singing in a stone, wood, and glass church. It is relatively new, rebuilt after a fire in a different building spread to the chapel. The shape is cruciform, with a relatively narrow nave, short and fat transept, and a very high and relatively open central area. The support beams are very heavy wood, bolted together, and somewhat open. The time was about eight thirty PM, and the weather was a steady rain that muffled some of the street noises from outside. The space tends to echo, although not for as long as you’d think – only two or three seconds. In comparison, the church where I sing most of the time, when we take out the pew pads, has a two second echo, and it is all wood and plaster, auditorium style. (With the pew pads it’s almost dead, unless you know just where to stand, and your voice happens to hit the room’s sweet spot. You can guess how I discovered this.)

Harmonics are not always desirable, in the sense that there are times when you don’t want to add notes to whatever you are working on. The technical term is a harmonic overtone, and you can get them at least two ways. One is what happens, usually in styles like Barbershop Quartet singing, where the vocal parts interact so that the waves from the upper part of the four notes are heard as a fifth note. Another way is when the choir, or soloist, finds a note or combination of notes that resonates with the structure around them, creating an overtone. This is usually either an octave or a fifth, at least based on my personal encounters with them. I grew up hearing it called “a harmonic,” although the proper term is overtone. It does not happen often, because everything has to be exactly right, clear, precise, and the sound waves from the different parts must interact in just the proper way. I only hear it with acapella music, but that might be because I sing so much acapella music.

The human voice does not produce a truly pure tone, not even boy sopranos and altos. What we do is produce a fundamental tone with partial tones around it. The fundamental is the “note” you want to sing (or play, for instruments) and the partials are sort of a fuzz above and below. Sort of like vibrato, but on a much less obvious scale (pun intended). How those partials interact leads in part to audible overtones.

This is not “overtone singing” like throat singing. It isn’t something the singer does physically, but how the acoustics interlock and respond.

For those who are curious, we got one on “O Vos Omnes” (Pablo Casals) and one on “Ave Maria” (Franz Biebl).

11 thoughts on “Harmonics and Echoes

  1. I’ll need to read up the math again. It sounds like a sidelobe gets amplified by resonance, so it come way up into audible level. Power appearing as a sin^2 function.

    It’s another ‘how does this happen?” question that calls for some advanced math and signal processing. Place the bases- right there- , to avoid destructive resonance and roof collapse. 🙂

  2. I have sung a variety of styles in my 50+ years of singing. Overtone/harmonic, call it what you will it’s thrilling to produce. Sang barbershop for about 10 years, there its called ringing a chord. Easiest to do on a pure major, can also happen on a 7th chord, especially one where the root is either in the bass or the tenor (upper most part called 1st tenor in other styles, the 2nd tenor is the lead and normally has the melody). I’ve done it in quartets and it raises the hair on your arm. Best place to do it is a stairwell or oddly a bathroom (likely all the nice echo from stone).

    • One of my favorite EweTube videos is a Mennonite choir in a stairwell, singing “Ye Shall Have a Song” by Randall Thompson. Both the acoustics and the sheer joy are a treat.

      • Singing almost anything by Randall Thompson is like that :-). Frostiana, his Alleluia, “Ye Shall Have A Song” is one I’ve managed to miss somehow in 50+ years of choral singing. His stuff was predominant when I was in High School and College.

        • The cantata “The Peaceable Kingdom” is not done all that often, in part because some of the imagery is very uncomfortable. And it is acapella, double-choir. I got to sing it in a Church of Christ sanctuary no less, so the acoustics were perfect for the work.

  3. You’re bringing back memories of what I did for a living with a ‘different’ set of fundamentals and harmonics… 🙂

  4. I built a harp once (from a kit) and when we were tuning it at the end I got some serious harmonics or overtones on the G string. The people around me then called it a wolf note. It does raise the hair on your arms…

    • I’ve heard that once, with an organ oddly enough. It led to some rapid adjusting and tweaking by the tuner to reset the pipe. (Assisting with organ tuning, as in being the person at the console holding down the keys/pedals is . . . boring after a while.)

  5. When we were kids, my younger brother and I often produced “beats” between our two voices. I thought it was cool, but adults didn’t. (And apparently it means we weren’t singing exactly the same pitch, even though I don’t think either of us were off-key in any way.

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