Anatomy & Physiology101: The Human Voice & Sound Production Pt.2
In Part 1, we explored the anatomy of the human voice—the structures that create sound. Now, let’s break down the physiology, or how these structures work together to produce and shape the voice.
The Physiology of Voice Production
Voice production, or phonation, consists of three key processes:
Breath Support & Airflow (Respiration)
Vocal Fold Vibration (Phonation & the Bernoulli Principle)
Resonance & the Source-Filter Theory
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1. Breath Support & Airflow
Breath is the foundation of a strong voice. When we inhale, the diaphragm contracts, pulling air into the lungs. When we exhale, air moves up through the trachea toward the vocal folds.
Why it matters:
Controlled airflow = A steady, powerful voice.
Too much air = A breathy voice.
Too little air = A weak, strained voice or tense voice
2. Vocal Fold Vibration & the Bernoulli Principle
The Bernoulli Principle is essential to understanding how the vocal folds vibrate to produce sound. This principle, originally described in fluid dynamics, explains how changes in air pressure and velocity allow the vocal folds to open and close in a rapid, rhythmic cycle.
How It Works:
When you exhale, air from the lungs moves upward through the trachea and reaches the vocal folds, which are positioned at the level of the larynx.
The vocal folds come close together (adduct) as the muscles in the larynx bring them into position.
Air is forced through the narrow opening between the vocal folds, known as the glottis.
Due to the Bernoulli Principle, as the air speeds up through this narrow space, the pressure between the folds decreases, causing them to be pulled back together.
This cycle of opening and closing repeats rapidly, producing sound waves that we recognize as the human voice.
What Affects Pitch & Volume?
Higher pitch = Faster vibrations (lengthened vocal folds).
Lower pitch = Slower vibrations (shortened vocal folds).
Louder voice = More airflow and stronger vocal fold closure (more mass of the vocal folds is vibrating
This continuous and complex interaction of airflow, muscle control, and pressure changes allows us to produce a wide range of sounds, from soft whispers to powerful belting.
3. Resonance & the Source-Filter Theory
Once sound is created at the vocal folds, it travels through the vocal tract, where it is shaped and amplified. This is explained by the Source-Filter Theory.
Breaking it down:
The "Source" = Vocal Fold Vibration – Produces a basic buzzing sound.
The "Filter" = Vocal Tract (Throat, Mouth, Nose) – Shapes the raw sound into speech or singing by amplifying certain frequencies.
How does this affect your voice?
Your mouth shape affects tone quality (bright, dark, nasal, warm, etc.).
Vowel sounds are created by adjusting tongue, lips, and jaw position.
Trained singers learn to adjust resonance for better projection.
Why This Matters
Understanding how the voice works can help you:
✅ Strengthen your voice & prevent strain
✅ Improve vocal clarity & resonance
✅ Recover from vocal fatigue
✅ Enhance projection for singing & speaking
I’m curious, what aspect of vocal physiology fascinates you the most? Get in touch!
By Radina - Vocal Coach & Speech-Language Pathologist