Jet Planes and Cord Closure

Jet Planes and Cord Closure

"Leaving on a jet plane!" That famous lyric holds a surprising truth about voice science. The same principles that allow a massive airplane to lift off the ground, stay in the air, and land safely are at work every time you sing a note. It all comes down to the Bernoulli Effect and the harmonious relationship between moving air and muscular coordination.

The Bernoulli Effect in Your Throat

Simply put, an airplane flies because air moves at different speeds above and below the wings, creating pressure variations that result in lift. In singing, a similar cycle occurs. As you exhale, air moves through the larynx. This flow creates a natural suction that draws the vocal cords together. Pressure builds up beneath them (sub-glottal pressure), forcing them open, and then the suction of the moving air snaps them shut again. This rapid cycle of opening and closing is what we hear as "vibration" or sung tone.

Sub-Glottal vs. Supra-Glottal Pressure

Just as there is air above and below a wing, there is air above the cords (supra-glottal) and air below the cords (sub-glottal). These different pressure zones help maintain the vibration cycle without extra effort from the singer. As long as the breath moves with the appropriate pressure variations and suction, the vibration continues effortlessly. Hooray for science!

The Partnership of Muscle and Air

It is important to understand that the vocal cords are closed by two forces working in tandem:

• Muscular Contraction: The arytenoid muscle system physically draws the cords together.
• Aerodynamic Flow: The air moving at a specific speed (relative to the size of the glottal slit) creates the suction needed for closure.

The glottal slit—the space between the cords—is naturally larger for lower pitches and smaller for higher pitches. The speed of the air must adjust accordingly to maintain the "lift" of the tone.

Striving for Unity of Action

In vocal training, we don't need to argue about which comes first—the muscle or the air. Instead, we recognize them as harmoniously interrelated. While a teacher might emphasize one over the other to correct a specific imbalance, the ultimate goal is unity of action. When the muscles and the air work together simultaneously, the voice achieves a level of freedom and power that feels as natural as flight.