Sing Bright Like a Diamond

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, bu