The purpose of this blog post is to simply explain in a practical way what resonance is to the voice user and how it can be used to increase the ease and efficiency of singing and speaking.
Titze and Verdolini – Abbot refers to resonance as “reinforcements of natural oscillations” (Vocology The Science and Practice of Voice Habilitation 29).
In physics resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at specific frequencies — Wikipedia
Resonance is vibrations that create tone through and within your mouth, throat, and nasal passages — Pamela Phillips, Singing for Dummies
In simplest terms, the voice is constructed of a power source (the lungs), a source (vocal folds also known as vocal cords) and a resonating tube(airways or vocal tract.) Furthermore, every voice vibrates and creates a pitch which is determined largely by the size of the vocal folds (please see blog post “But Size Does Matter.”) That resonating tube has certain characteristics, which influence the sound created; however, by understanding the ABCDs of resonance we can use the information to change to conform to social requirements, or to improve it to ensure greater efficiency, ease, and a reduction of work.
I picked ABCD to stand for a variety of concepts that are needed to understand what resonance really is and how we can change it. A stands for the throat and the mouth where the air flows in and out. B stands for how vibrations are made by the vocal folds and then are changed in the throat and mouth. C stands for the Combinations of vibrations that happen as we actively change the space in our mouth and throat. These combinations create the unique sounds that makes the speaker or singer identifiable. Finally, D stands for the Destination where we “feel” these vibrations.
Whenever a sound is created that pitch is known as the Fundamental Frequency. It is the lowest pitch in a pattern that can be measured as multiples of the original pitch in an idealized model. If I produce a pitch on a string that vibrates 100 times a second, that then influences the “air” molecules to vibrate 100 times a second. This then causes another pitch which vibrates at 200 times a second, and then another pitch which vibrates at 400 times a second. Theoretically this happens forever. These are called Harmonics. Your vocal folds play the part of this string. For example, if a baritone happens to produce a pitch of 100 vibrations per second there will then be harmonics that follow that pattern of 100, 200, 400. (This is a simplified pattern. For a more complete pattern of harmonics please see Tontechnick-Rechner.)
The vocal tract is composed of basically two airways: the throat and the mouth (yes the nose plays a role at times, but for simplification I am leaving out the nose.) This is where these harmonics are first sent. This is also where something really amazing happens. Each of these tubes have their own frequency. Just as a coke bottle or a crystal glass has a certain “ring”, each tube takes the original pitch as well as the harmonics and changes it. These are known arguably, as overtones. They are overtones and NOT harmonics because the tube that produces them changes the pitch so they may not be exact multiples of the original pitch. Our bass who produced a 100 vibrations a second (approximately a sharp G2 on a piano), has a harmonic of 200, but when that tone hits the throat there might be an overtone of 215 vibrations per second. The throat isn’t the only pipe there is that changes that pitch. The sound also comes out of the mouth (again, yes sometimes the nose a bit, but mostly the mouth). The mouth also has its own vibration so our imaginary bass with his vocal folds vibrating at 100, which produces a pitch, which then produces a series of harmonics, also has a “throat” overtone of 215 and a “mouth” overtone of maybe 436. Remember these numbers refer to Hertz or more correctly vibrations per second. The original pitch is always the lowest. The throat will be lower than the mouth, because generally it is longer and will have a lower “frequency.” This leads us to the C of the ABCDs of Resonance.
COMBINATIONS of VIBRATIONS
Now we get to the fun part. Dr. Seuss was right when he wrote “…there is no one who is more youer, than you!” While we all know what a human looks like and what a vocal tract should look like, each human has slight differences. For instance, the range of normal for the human pharynx is 12-14 centimeters (Granger). Add to that the magnificent variations in a mouth, which can be produced not only by the actual skeletal structure, but also, by size and placement of the teeth; the size and placement of the tongue, lips, and palate; and you have probably an infinitesimal number combinations in the structure of a human’s vocal tract. These structural variations produce our audio palette, if you will. Each pitch is colored by the unique pattern of resonance or vibrations that your particular combination of vocal fold, pharynx, and mouth (oral cavity) can produce; but wait there’s more!
We can change our mouths (and our throats a bit), but mostly our mouths. We have lips which can make mouths bigger or longer, or wider. We have a tongue which we can move accordingly to decrease the space in our mouths or increase it. We can even raise and lift our soft palate to lengthen our pharynx and block off our nose. We do this all the time in order to produce vowels (consonants too but vowels are more important for resonance).
Now each time we produce a vowel we then create a different pattern in the overtones. Each vowel has at least three different perceivable resonations which we call formants. The first and lowest formant is produced by the pharynx, the second highest is produced by the mouth. The lower the number of the formant the bigger the space in the throat or mouth. The higher the number the less space is available. For instance, Wikipedia has a chart that says /i/ said as ee as in beet has a first formant of 240 Hertz and a second formant of 2400.
If you say /i/ you will notice your tongue is right behind your teeth. This placement keeps the tongue out of the throat (increasing the resonating area there and decreasing the space in the mouth.) The third formant, not always listed in charts, provides a hint as far as whether the vowel is rounded or unrounded. There are actually more formants per vowel (anywhere between four and six), however, your brain usually needs only the first two to determine what vowel is being produced.
So we have a combination of vibrations which determines what we sound like and what we say. How can we use this though? Overtones are produced because of how we are put together as a human being, and formants are produced because of how we make a vowel, why do singers, voice teachers, and others talk about changing the resonance so much?
This brings us to the D of resonance. Speakers and singers will often talk about how they “place” their resonance, or the feeling of vibration in their sound. This is very confusing, as the literature uses some of the same terms to describe register with a couple of extra terms. This includes chest resonance, head resonance, mouth Resonance, mask and face resonance, and nose resonance. So the question is “Can you change where you resonate?” The answer, as I understand it, is: Yes sort of….
What we haven’t discussed is that all of these resonance: overtones, harmonics, and formants can be made to be louder or softer, or more correctly amplified or dampened. This is one of the main ways we can affect resonance. How do we do this? We change the shape of our vocal tract of course. Vocalists might not even be aware they are changing the shape, but when asked to loosen up the tongue when singing, or to place your hand on your chest and feel a vibration there we are changing something in our mouths and throats.
Kathy Rundus in her vocal pedagological book Cantabile provides some simple exercises to experience the change of resonance in three dimensions just by shifting the vowels produced.
Try it yourself:
In summary, resonance is a term which can cause confusion when speaking about the voice. However, understanding the aspects of resonance by remembering the ABCDs of resonance, may help understand your voice, use your voice healthfully, and sometimes change the perception of it by others.
If you are interested in exploring how using resonance may help you when you use your voice as a singer, teacher, or other professional who needs a healthy, functional, and flexible voice; or if you need help in changing how your voice is perceived by others, contact me. Together we can come up with a plan to help you use your voice with congruity in your life.
Trissa DiBenedetto WAlter
Is a singer, voice teacher, speech language pathologist, and certified vocologist