Grades 6–8 · Organisms
How does your voice box produce different pitches?
Your voice box, or larynx, sits above the windpipe. Inside are two folds of living tissue called vocal folds. For many voiced sounds, muscles bring these folds close together while air from the lungs passes between them.
In the diagramAirflow drives repeated tissue vibrationair from lungstoward throat and mouthvocal foldRepeated openings set the vibration rateMuscles adjust tissue properties; the folds vibrate with airflow.
Air pressure and the elastic behavior of the tissues set up repeated opening and closing. These vibrations create changing pressure in the air above the folds. The folds are not tiny strings plucked once, and the brain does not send a separate command for every vibration.
Muscles adjust the folds’ length, tension and effective vibrating mass. Together these changes affect how rapidly the folds vibrate. Faster repeated vibrations generally produce a higher voice pitch. Changing airflow and the pattern of vibration also influences the sound.
The throat, mouth and nose then reshape that sound by resonance. Your tongue and lips change the spaces and openings, helping form speech sounds. Pitch begins largely with the vibration rate at the larynx; vowel quality depends strongly on how the sound is filtered above it.
About this explanation
Starting knowledge: Understand airflow from the lungs and frequency as repetitions per second.
Sources
- National Institute on Deafness and Other Communication Disorders — How Does the Human Body Produce Voice and Speech?