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One of the ritual elements of the yoga classes I’ve been doing is the chanting of the word “Om” together—three times at the start and once at the end. The instructor starts and we join her, some of us matching pitch, some not. I love it when most of us are in tune, not just because of my delicate ears that are easily offended by anything off-key, but because I get to experience a whole new level of Om.

When we are in tune and I can maneuver just the right resonating shape to my mouth, I start to feel the overtones produced by the consonant vibrations in the room. My voice alone is not enough to excite the overtone series to an audible level. With the reinforcement of others, I hear—and actually feel—the overtones at play in my mouth. For some reason the 4th overtone is often the strongest. Sometimes I only hear the 1st (or 3rd?). The more in tune everyone is, the more overtones I can distinguish. When there is a bass in the class the overtones are most vibrant because having the fundamental down the octave makes the higher-order overtones much more noticeable.

For the physics background—when you have a resonating cavity of air (in the mouth of a singer, the bore of a flute, etc.) the main note you hear is but one of many frequencies (pitches) that are resonating in the cavity. However, there is a relationship among the allowed frequencies, due to the number of wavelengths that can fit in the cavity exactly. The lower order overtones are the strongest in volume, and the most harmonic with the fundamental pitch. The beginning of the overtone series goes:

  1. up 1 octave from the fundamental pitch (e.g. C4, “middle C,” if C3 was the fundamental)
  2. up a 5th from the 1st overtone (e.g. G4 given C3 as the fundamental)
  3. up a 4th from the 2nd overtone, thus up 2 octaves from the fundamental (e.g. C5 if C3 was the fundamental)
  4. up a major 3rd from the 3rd overtone (e.g. E5 for C3)
  5. up a minor 3rd from the 4th overtone (e.g. G5 for C3)

For those paying careful attention we have now touched on all the notes in the major triad, going from 1 to 1′ to 5′ to 1” to 3” to 5”. From there on up, the overtone series covers ever more bases, and also deviates more significantly from the equal temperament scale (think piano keyboard) in pursuit of the mathematical purity and physical reality of the overtone series.

If you have a cavity whose shape you can manipulate, you can reinforce the strength of different overtones—I find for the chanting in yoga class it feels like a narrowing of my palate to capture the right overtones, but it must involve my tongue somehow. The space just above my tongue feels wide, but my palate feels narrow. If you’re exceptionally good at manipulating the shape of your resonating cavity to produce an audible overtone note while you are still sounding the fundamental, you may have a career opportunity as a throat singer :) Wikipedia says this ancient art may have originated in southwestern Mongolia, but you’ve most likely heard of it as Tuvan throat singing or Tibetan throat singing.

I’ve felt a similar effect in choral singing before where I can feel the notes the other singers are singing resonating in my mouth as I sing, but with the purity of the tone and pitch of singing “Om” together I can be much more clearly aware of the individual overtones. As I focus on them my awareness seems to bounce around from one to another, giving it a feeling of dancing or playing. I don’t know whether this is just due to my awareness, or to subconscious shifts in the shape of my resonating chambers to reinforce what I’m hearing.

When our group is not in tune I can feel the character of our out-of-tuneness—sometimes it feels like people having a cranky day, not ready to settle into this intense awareness of other people’s pitch. Sometimes it’s the awkwardness of newbies hastily singing, caught off guard, finding the pitch with a stab in the dark. But when we get it right and all the angels are singing right there in my mouth I experience a deep joy and sense of connection that the word “Om” must be designed to elicit.

So wish me yoginis and yogis with good ears, and a few good basses in the mix!

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