Harmonics are nifty. It's just one aspect of voices that I find endlessly fascinating. How singers use and manipulate harmonics is a really fun part of pedagogy and voice science, and one that is still being actively researched and expounded upon.
Today's post is the third in a series focused on how we use semi-occluded vocal tract exercises, or SOVTEs, in the voice studio. (Read Part 1 and Part 2 to get caught up.) Some types of SOVTEs can impact upper harmonics, which increase the brightness of a singer's sound. Let's get deeper into how that works and why we might care, or not.
Vocal harmonics
When you sing or speak, you are making multiple notes happen all at the same time. In the spectrogram image below, I sang an [a] vowel at a moderately loud dynamic for five seconds, as indicated by the numbers along the bottom of the graph. (If you're used to spectrogram images, you might skip down below, but if you're not, get ready, because this stuff is cool!)
The numbers along the left side are kiloHertz, so each number is multiplied by 1000 to get the number of cycles per second in each harmonic. The fuzzy purple stuff in between the lines is basically noise in the sound. That's both noise that's occurring in my voice, and likely fan noise from my laptop. Probably the brighter purple/red fuzz at the bottom is laptop fan noise that the mic picked up.
Now, each line is a harmonic, or a frequency, that when added all together, makes up the sound of the [a] that I was singing. The brighter the color, the greater the sound pressure of that harmonic, which is normally measured in decibels. The sound pressure level measurements are not included in this graph, but we can get information from the relative loudness of them just by looking at the colors. Notice how the harmonics are evenly spaced. That's nifty! It's math in our singing. I love that part.
The bottom line is what we call the fundamental, or F0. Many times the zero is written as a subscript, but to be honest, I don't know how to do that on this blog software, so forgive me for that. The fundamental is the note that we all perceive that I'm singing. So you might tell me to sing an A440, and I would sing an A440, but I would also be singing evenly space harmonics, or notes, above that A, and you wouldn't necessarily hear them. This is a little bit tricky, but stick with me.
Our brains do hear all of those notes, but it is filtered in such a way that we only really listen to the fundamental, and the rest of those harmonics are added together to create timbre. A really simplified definition of timbre is the quality of the sound, or what makes a sound distinct from other sounds. Voices don't sound like trombones, for example, because even if a voice and a trombone are singing/playing the same fundamental, the harmonics are going to be filtered differently, and so those two sounds are distinct.
I'm not going to get into formants today, except to say that the brightest/loudest harmonics are generally formants. The bottom two lines are formants 1 and 2, and those determine vowel sounds and color. So those are important in speech and in singing. Where things get really interesting is what singers do or don't do with the upper harmonics.
Those upper harmonics can give voices a big ol' boost, making the voice more prominent and easier to project. You may have heard of the "singer's formant," which is an upper harmonic that when boosted, gives voices the ability to project over an orchestra without amplification. It makes opera singers happy. It's what creates "ring" in a classically-trained voice. If you're singing art song or opera, you want that harmonic to be working in your favor. (If you're a soprano, there's a lot more to say about this subject for you, and I'm going to totally ignore it today. I might get to that at a later date, but simply don't have time for that now. For now, just keep doing what you're doing.)
Here's where SOVTEs come in
Certain SOVTEs can help to manipulate the way pressure is distributed in the vocal tract, which can influence how fast the vocal folds close and open, and the pressure of the air moving through the glottis (the opening of the vocal folds). When things are working optimally in that direction, all that manipulation can boost the energy in the upper harmonics, which gives the voice a sense of brightness. That brightness is very often a desirable quality in singers, because it gives the voice a different color, better projection, and can conform to the Western ideal of singing. In other words, it can give the singer some more colors to play with in the tonal palette, and help to project with less effort.
But Dr. Nelson, I don't really care about all that.
Fair enough. For some singers, like those who sing in non-Western traditions or those in CCM singing who don't need to project without amplification, boosting the upper harmonics is not something they're looking to do. And that's totally fine. Those singers can experiment with SOVTEs for other reasons, or skip them. Whatever your client's vocal goals are, that's the guiding factor anyway. But if you'd like to play around with the upper harmonics simply to explore what the voice can do, it might be a fun experiment.
Just for funsies, I redid the spectrogram after doing a few minutes of straw singing, and this is what the harmonics looked like:
You might notice that there is a bit more brightness in the color of some of those upper harmonics, indicating a bit more sound pressure (decibels) in those harmonics. I think that's kind of cool.
You can try experimenting with harmonics and SOVTEs, too. There are several free versions of spectrogram software available online. I used this one for today's images: https://auditoryneuroscience.com/acoustics/spectrogram
If you try it out, I'd love to hear what you notice! Comment below or send me a DM through Instagram. And if you'd like to geek out even more about SOVTEs, this month's Pedagogy Happy Hour is going to be right up your alley. I'm going to talk more about the science behind them, some ways to use them in your teaching, and we'll try several of them together. You can register for the webinar, to be held on Thursday, July 28th at 7:00 p.m. Central time, by clicking the button below. Send me your questions before the event, and I'll be happy to research what I can find and we'll talk about it. I hope to see you then!