Plant Bioacoustics and a Defense of Noise
In my last post, I mentioned Suzanne Simard’s research into tree signaling and communication via soil mycelia. Having done some writing, recording, and experimentation on the related topic of plant signaling via bioacoustics, I’ll try to give an update on how that’s going, as I am back on that bullshit. [Edit: I got distracted by alternate tuning and tonal systems and give a spirited defense of noise. It’s probably way more interesting than a summary of me putting contact microphones in potted plants.]
After decades of fits and starts, plant neurobiology entered the scientific community in earnest in 2006, when Eric Brenner and five coauthors published “Plant neurobiology: an integrated view of plant signaling.” There were numerous questionable assertions in the paper, in particular the term “plant neurobiology.” Plants lack neurons, making the study of their neurobiology rather difficult.
Despite confusing questions of terminology, and some pretty big leaps about plant intelligence in the research that followed in the subsequent decades, what is becoming clear is that plants really do respond to their environments in often surprising and complex ways. Pea plants will move their roots toward the sound of water, even in the absence of actual water. Trees will request and share resources through fungal networks. Corn, or maize, will emit clicks and pops in response to specific frequencies.
I have made and released recordings of these sounds that maize makes. My initial recordings were done with domesticated corn, Zea mays spp. mays. I recently started recording teosinte, or Zea mays spp. parviglumis, the wild ancestor humans domesticated into corn. These are varieties of the same species, and my preliminary findings are that teosinte makes sound in response to the same frequencies as corn. There may be some differences, but this will hopefully be determined definitively with further recordings.
There is obviously a lot to say about this, but as a musician (and middle-aged enfant terrible) doing this, the frequencies I use are not just practical for the purposes of the experiments, but are also experimental music in-jokes and attacks on some niche theories about what are “good” and “bad” sounds.
When I wrote about my initial recordings of Zea mays spp. mays, I began by re-debunking the long-debunked belief that plants prefer classical music. Plants lack brains, neurons, and eardrums. In addition to the fact that the initial experiments were never successfully reproduced, why would we even expect another order of life to be acculturated to the tastes of the ruling classes from the leading imperialist nation-states?
When I put two of these recordings on a 7” record, I chose to use their responses to 220 Hz and 216 Hz. There are specific reasons for this. Monica Gagliano, who made the discovery that Zea mays will make sound in response to sound, noticed that the highest response rate was in the 200-300 Hz range. Anything in that range works well. But I chose these particular tones because they are one octave down from “middle A” on a piano in Western concert pitch (440 Hz), and “middle A” on a piano in an alternate system that many New Agers believe is more “natural” and in harmony with the Universe (432 Hz). (I’ll just mention right away that Zea mays didn’t seem to prefer one over the other.)
Defenders of 432 Hz will tell you that “432 Hz resonates with 8 Hz (the Schumann Resonance), the documented fundamental electromagnetic ‘beat’ of Earth. It just feels better.” This seems pretty compelling. But if you leave that article about the powers of 432 Hz and find one about the Schumann Resonance itself, you will learn that it varies from 3 Hz to 60 Hz, with a half dozen or so regular peaks between 7.83 Hz and 33.8 Hz. Where that 8 Hz number comes from is a mystery. (Additionally, 440 is easily divisible by 8, so what makes 432 such a special number in comparison is pretty unclear to me.)
But one of the weirdest things about 432 Hz aficionados is that that their system of music maintains the exact same space between notes as Western music in the 440 Hz system. It’s the same system, it just starts at a different point. Whether in 432 Hz or 440 Hz, the twelve tones of the Western scale are spaced in “equal temperament.” In “equal temperament,” each note increases by the same factor from its predecessor—in this particular equal temperament system by 1.05946. Equal temperament allows for easier transposing between octaves, but creates a new set of problems that angers a new set of people.
Before equal temperament became standard in Western music (as well as in various musical systems throughout the world right up to the present), notes were determined in ratios to each other. An octave is a doubling, or a 2:1 ratio. The “A” after 220 Hz is 440 Hz. This is an octave. A major third is a 5:4 ratio. So “A” at 220 Hz and “C#” at 275 Hz constitute a major third. A fifth, or the middle point in an octave, is a 3:2 ratio. “A” at 220 Hz and “E” at 330 Hz are a fifth.
But with equal temperament, and in particular with the uniform factor of 1.05946 used in Western music, those ratios get messed up. Sure, you can move more easily between octaves, but everything gets a little dissonant. For instance, that “C#” is not at 275 Hz, but becomes 277.18 Hz. It’s 2.18 Hz sharp! And that “E” isn’t 330 Hz, but 329.63 Hz. It’s .47 Hz flat! So an A major chord on a perfectly tuned piano is simultaneously sharp and flat from the ratios that the notes were meant to emulate. Just like standard 440 Hz equal temperament, 432 Hz equal temperament is internally out of tune with itself. It just does it 8 Hz lower.
Composers like La Monte Young, with his “well-tuned piano,” and Harry Partch, with his 43-or-more-tones-to-the-octave-just-intonation, rejected the internal dissonance of equal temperament to compose with perfect ratios. As I kind of hinted to a moment ago in my-dash-heavy-summary-of-Harry-Partch, this is usually called “just intonation.”
So we have the 432 Hz fans who think the Western scale is a perfectly fine way to space your notes, but you need to start in a different place. And then we have the just intonation supporters who think you can start anywhere, as long as you do your math right and your ratios are accurate. Both groups insist our music is making us crazy, but for totally different reasons.
When I recently recorded teosinte plants responding to sound, I tried it with single tones, then major thirds in equal temperament, just intonation, and also one dissonant interval. These were 220 Hz/275 Hz, 220 Hz/277.18 Hz, and 220 Hz/234.1 Hz. If you want to hear these tones, open a browser tab with an online tone generator, type in the frequency, and then open another tab for the next tone. It’s fun and fascinating. (At some point, I’ll need to try a set of 432 Hz justly intoned and equally tempered intervals.)
But so far, the plants don’t seem to care about the intervals. If anything, they “prefer” single tones over dyads. Similar responses from the plants come from 216 Hz, 220 Hz, different math for the intervals, and from dissonance. But maybe we shouldn’t expect our human tastes to appear in plants.
There is a lot to say about this, and I could clear a room faster than a dissonant sine tone once I get going, since I could go on and on and on and on and get really pedantic about it. For now, I’ll close with a quote from John Cage, the composer most known for his “silent piece,” where the various sounds in the performance space become the music. An interviewer asked Cage about Harry Partch’s octaves of perfect ratios with almost four times as many notes per octave as the Western scale. “One difference between Partch and myself—also a difference between myself and Lou Harrison—is that they became interested in intonation and control of microtones, whereas I went from the twelve tones into the whole territory of sound. I took noise as the basis of it. I don’t try to make the situation between what is musical and not musical more refined as both Partch and Harrison do; but I start from the other direction, from noise.”
Cage is right. We don’t need to discover the “most correct” tones and intervals, or most natural, and then discard the rest. Every sound is natural. If you can hear it, it is happening in nature, and you, an inhabitant of the natural world, are taking it in with your auditory organs, produced through eons of natural evolution. We don’t need to find the “right” notes and intervals. We need to listen to the world. It’s all natural. Accepting the full spectrum of sound is so much more exciting than some endless argument about what notes are the right ones. Embrace every sound, and everything becomes music. And that’s when we’ve really realigned ourselves to the natural world.