Pitch Production: What’s the Buzz?
From Silence to Sound
Pitch refers to the relative "highness" or "lowness" of a sound based on the rate of its vibrations. In this blog post, we examine the underlying mechanisms and physics that help us produce pitch. Previously, we explored how breathing works and how exhaling provides the fuel for voicing. As discussed in that post, on an exhale, the breath travels up, out of the lungs, up the trachea and through the larynx, which is located in the throat. It is here that the next step of speech production takes place, as one of the larynx's jobs is to convert the air from silent wind to the carrier of sound waves. The act of producing sound this way is referred to as phonation, and is the main subject of today's blog post.
The Larynx: Phonation Station
Where is it?
Place a finger on your chin, and slowly move it down the front of your throat. The first large bump you should feel is the thyroid notch, also known as the Adam's apple if you want the fun gendered term for it. This projection of the larynx is designed to protect the delicate musculature of the vocal folds, the source of the vibrations that comprise the base of your voice. Keep moving your finger down our throat, until you feel a small hard ring of cartilage. What you're feeling is the cricoid cartilage, which is the connecting cartilage between the larynx and the trachea below. That's the entire length of your larynx!
How Voicing Works
At this point in the voicing process, we have breathed in, and have begun to breathe out. Air is rushing up from our lungs through the trachea, through the larynx and up into the pharynx, or the area directly above the larynx. When the muscles of the larynx are at rest, air rushes through the larynx unimpeded. When certain laryngeal muscles are activated, the vocal folds are adducted, or brought to the middle. The air now has to push through the vocal folds on the way out of the lungs. The vocal folds are pushed apart (or abducted), then slam back together, then pushed apart again, in an incredibly rapid cycle. The buzzing produced by this cycle is your voice; the number of cycles per second is how we measure a voice's pitch! The more cycles per second, the higher the pitch; the fewer cycles, the lower the pitch.
Take a look at the video below to see vibrating vocal folds in action:
Changing Vocal Quality
Intensity
Starting at 1:14 in the video above, you can see the client produce three different levels of vocal intensity. Not much visibly changes at these different volume levels; in the louder samples, her vocal folds come together with more force, resulting in a slightly louder, harsher quality; however, where the bulk of this intensity comes from is the amount of air pressure coming up from the lungs. When one increases the amount of pressure on their lungs via the diaphragm, the amount of air passing through the vocal folds increases, making the resulting vibrations larger.
Pitch
The way one changes pitch is very clearly demonstrated in the video above starting at 1:33. Here, we can see the patient shift their larynx in order to increase her pitch. The vocal folds work similarly to the strings on an instrument (you can also simulate this by plucking a rubber band); if the string is pulled tight and long and plucked, a higher pitch will be produced. If the string is shorter and looser, the resulting vibrations are much slower, and the pitch produced drops accordingly.
At 1:35, we can see the patient rapidly adjusting the tension on her vocal folds back and forth between tighter and looser. The resulting effect is the wavering of pitch known in singing circles as vibrato.
Breathiness
The client producing voice in the video above does not have a very breathy quality. Compare the vibrations you see in that video to the ones in this very short video below where this person produces a very breathy voice:
In the video higher up on this page, the client's vibrations traveled the full length of their vocal folds; you can see the entire wave of motion carried through the full length of the fold. In the video directly above, we see that this client has a gap at the back of their vocal folds; only a little over half of the folds are vibrating. This gap allows extra air to rush through, which is what gives breathy voice its distinct quality.
Falsetto
Speaking of distinct vocal qualities, compare both of those vibration patterns with this video of falsetto:
Seizure warning due to poor video quality
You can see that the back ends of the vocal folds are clamped together. This forces the air through a narrower space, which greatly increases the rate of the vibrations, thus increasing the pitch.
What's Next?
That concludes our introduction to pitch! At this point, our diaphragm is providing sustained pressure to the lungs, pushing air up and out of the lungs, through the larynx. Our vocal folds are adducted with air rushing through, causing the folds to separate and come together in a strong, regular vibratory cycle. These vibrations are traveling up our vocal tract, into the chambers above. It is here that the next step of voicing takes place: resonance. We will discuss this phase in the near future!
I hope this article was fun to read and engage with. Please let me know if I can provide any clarification; I want all of my articles to be as accessible as possible!
Be well,
Leave a Comment
(0 Comments)