Your voice box, or larynx, produces sound by pushing air from your lungs through two small flaps of tissue called vocal folds. These folds vibrate hundreds of times per second, creating a buzzing tone that your throat, mouth, and tongue then shape into speech. But the larynx does more than make sound. It also protects your airway when you swallow and helps regulate breathing.
The Parts Inside Your Larynx
The larynx sits at the top of your windpipe, roughly at the level of your throat. It’s built from a framework of cartilages connected by small, precise muscles. The largest is the thyroid cartilage, the shield-shaped structure that comes to a point at the front of your throat. That point is commonly called the Adam’s apple. The thyroid cartilage fits over a ring-shaped piece called the cricoid cartilage and is hinged so it can rock slightly forward and downward.
Sitting on top of the cricoid cartilage at the back are two small pyramid-shaped pieces called the arytenoid cartilages. These are the workhorses of voice production. They can rock, glide, and pivot, and the vocal folds attach to them at one end and to the inside of the thyroid cartilage at the other. Every time you open your vocal folds to breathe or close them to speak, it’s these arytenoid cartilages doing the work.
The vocal folds themselves are surprisingly small. In adult women, they measure roughly 1.25 to 1.75 centimeters long. In adult men, they range from about 1.75 to 2.5 centimeters. That’s roughly the size of a dime to a quarter, yet they produce every sound your voice can make.
How the Vocal Folds Make Sound
When you breathe normally, your vocal folds stay open so air passes through silently. When you speak, muscles pull the arytenoid cartilages in a way that brings the vocal folds together, closing the gap between them (called the glottis). Air pressure from your lungs builds up below the closed folds until it pushes them apart. As air rushes through the narrow opening, the folds snap back together, and the cycle starts again.
This open-close cycle happens extremely fast. During normal speech, the vocal folds vibrate at a fundamental frequency of roughly 100 to 400 Hz, meaning they open and close 100 to 400 times every second. The vibration isn’t a simple flapping motion. A ripple travels across the surface of each fold from bottom to top, similar to a wave moving through a flag in the wind. This ripple, called a mucosal wave, is what actually sustains the vibration. The wave makes the shape of the opening change as the folds move apart versus when they come back together, and that difference is what keeps transferring energy from the airstream into continued vibration.
The sound the vocal folds produce on their own is a raw, buzzy tone, rich in overtones but nothing like recognizable speech yet. Turning that buzz into words happens farther up the vocal tract.
How You Control Pitch
Pitch depends on how fast the vocal folds vibrate, and you control that speed by adjusting their length, tension, and thickness. Two sets of muscles do most of the work, pulling in opposite directions like a tug of war.
To raise your pitch, muscles tilt the thyroid cartilage forward, stretching the vocal folds longer and making them thinner and tighter. At high pitches, only the outer layer of each fold vibrates while the deeper muscle layer essentially uncouples and stays still. This reduces the vibrating mass, allowing the folds to move faster and produce higher frequencies.
To lower your pitch, muscles inside the vocal folds themselves contract, pulling the back end of each fold toward the front. This shortens and bunches up the folds, making them thicker. With more mass vibrating, the folds move more slowly and the pitch drops. At low pitches, all the layers within each fold are coupled together, so the entire thickness vibrates as a unit.
How You Control Volume
Loudness comes primarily from how much air pressure your lungs generate below the vocal folds. The relationship is steep: vocal intensity rises roughly in proportion to the subglottal pressure raised to the 3.3 power. In practical terms, a modest increase in air pressure produces a dramatic jump in loudness.
How you get louder also depends on what pitch you’re at. At low pitches, your larynx does most of the work. The vocal folds press together more firmly, increasing resistance to airflow. Surprisingly, airflow can actually decrease as you get louder at low pitches, because the tighter closure restricts how much air escapes. At high pitches, the story reverses. The vocal folds maintain a relatively constant resistance, and you get louder mainly by pushing more air through them using your breathing muscles.
How Your Throat and Mouth Shape Speech
The buzzy tone from the vocal folds travels upward through the vocal tract, the tube-shaped space that includes your throat (pharynx), mouth, and nasal passages. This tract works as a filter. Different areas resonate at different frequencies depending on their size: larger spaces amplify lower frequencies, and smaller spaces amplify higher ones.
The two most important resonating spaces are the throat and the mouth. The throat produces the lowest resonant frequency, and the mouth produces the next one up. By moving your tongue, lips, and jaw, you reshape these spaces and change which frequencies get amplified. This is how you form vowels. For an “ah” sound (as in “father”), the tongue sits low and back. For an “ee” sound (as in “keep”), it moves high and forward. For an “oo” sound (as in “loot”), it goes high and back. Every other vowel falls somewhere between these three extremes.
Consonants involve additional maneuvers: your tongue tapping the roof of your mouth, your lips pressing together, your teeth touching your lower lip, or air hissing through a narrow gap. The larynx provides the raw material, but the vocal tract sculpts it into language.
Protecting Your Airway
Your larynx sits at a crossroads where the path for food and the path for air share space, which creates a choking risk every time you swallow. The larynx solves this with a coordinated sequence of movements. When you swallow, muscles pull the entire larynx upward and forward, tucking it under the base of your tongue. At the same time, a leaf-shaped flap of cartilage called the epiglottis folds backward over the opening of the larynx like a trap door. The vocal folds also snap shut to create a seal. Together, these three actions redirect food and liquid into the esophagus and away from the windpipe.
This protective reflex is why you can’t breathe and swallow at the same time. It’s also why problems with the laryngeal muscles or nerves can lead to food or liquid slipping into the airway, a dangerous condition called aspiration.
How the Voice Changes With Age
The larynx undergoes its most dramatic transformation during puberty. In both boys and girls, the vocal folds grow longer and thicker, which lowers the pitch of the voice. The change is far more pronounced in boys because testosterone causes the larynx to grow significantly larger. The thyroid cartilage tilts to a steeper angle, creating a more visible Adam’s apple, and the vocal folds can nearly double in length. This rapid growth is what causes the voice to crack during puberty, as the brain’s muscle coordination hasn’t yet caught up with the new dimensions.
In girls, the vocal folds grow somewhat but not as dramatically, producing a more subtle deepening. By adulthood, the difference in vocal fold length between men and women (roughly 1.5 cm versus 2 cm on average) accounts for the typical gap in pitch between male and female voices.