Laboratory

The voice laboratory.

Two full simulators, controlled with your own hands: the physics of the voice (source, filter, techniques, and live spectrum) and the vocal system (anatomy, production chain, and glottal wave). All conceptual: general physics and anatomy, not a measurement of your voice or of any system.

🎤 The Physics of the Voice

Source · Filter · Resonance

Este simulador necesita JavaScript para funcionar. Actívalo para explorarlo, o consulta los artículos del blog con ejemplos ilustrados (armónicos, formantes, anatomía laríngea, espectrograma).

🎸

SOURCE

Vocal Folds
Generate harmonics

→

🎺

FILTER

Vocal Tract
Formants F1–F4

→

✨

RESULT

Final Timbre
Twang, Belting…

La Fuente: Cuerdas Vocales

The vocal folds generate a wave rich in harmonics. How open they are determines which harmonics dominate.

🎹 Fundamental Frequency (Note)

La3 220 Hz Octave 3

Low High

Quick notes:

💡 Notice: As the note rises, the harmonics rise (H1=f, H2=2f…) but the formants stay put. That’s why high notes often need you to adjust the vocal tract (e.g. opening the jaw for belting).

〰️ Vocal Fold Vibration

View mode:

📊 Source Spectrum (Glottis)

220Hz 880Hz 1760Hz

🔊 Glottal Aperture 55%

🔒 Closed 😬 Tight ✨ Optimal 💨 Breathy

✨ Optimal Zone — H1 dominant

El Filtro: Tracto Vocal

The vocal tract has natural resonances (formants) that amplify certain harmonics.

Técnicas Vocales

Different tract configurations produce characteristic vocal effects.

🎵 Select a technique

Click a vocal technique to see how it affects the formants and the resulting spectrum. Each technique has a specific vocal-tract configuration that amplifies different harmonics.

💡 What’s happening right now?

🎸 At the Source (Glottis)

With aperture at 55%, the vocal folds have optimal room to vibrate. H1 (the fundamental) clearly dominates over the other harmonics, indicating efficient, tension-free vocal production.

The Result

The timbre is balanced and natural. The fundamental is clear, with well-distributed harmonics. It’s a relaxed spoken-voice sound, with no special projection or color characteristics.

📊 H1/H2 ratio: H1 > H2 — Relaxed vocal folds

🎯 Amplified harmonics: H3, H4 (F1 zone)

🔊 Sound character: Neutral, balanced, natural spoken voice

El Resultado: Espectro Final

Source × Filter = the timbre we hear. Harmonics that coincide with formants get amplified.

✨ Resulting Spectrum

⚡ = Harmonic amplified by matching a formant

220Hz 880Hz 1760Hz

🔊 Listen to Vowel "A"

A F1: 700 Hz | F2: 1200 Hz

Source only: the “raw” sound of the glottis (like a buzz)
With filter: the sound shaped by the vocal tract (the vowel)

🧬 Anatomy of Vocal Production

Source-Filter Theory

Este simulador necesita JavaScript para funcionar. Actívalo para explorarlo, o consulta los artículos del blog con ejemplos ilustrados (armónicos, formantes, anatomía laríngea, espectrograma).

Sound Production Chain

Subglottal Pressure

The diaphragm and abdominal muscles generate a column of air at controlled pressure (Psub). It’s the energy that powers the whole system.

Glottal Vibration

The vocal folds close (adduction) and the air forces them to open cyclically (Bernoulli effect + elasticity). This generates the quasi-periodic fundamental wave.

Mucosal Wave

Reinke’s layer ripples over the body of the vocal fold, generating timbral richness and the harmonics. It’s the acoustic “signature” of the glottal sound.

Tract Resonance

The vocal tract acts as a filter: it amplifies the formants (F1–F5) and shapes the timbre. It doesn’t create sound, it transforms it. This is where the “singer’s formant” is born (~2800–3400 Hz).

Acoustic Radiation

The sound leaves through the mouth (and nose) into the space. The resulting signal is what a microphone captures and an acoustic analyzer processes.

Glottal Wave Simulation

F0 (Hz) 220 Hz

Jitter (%) 0.5%

Glottal Closure 80%

Pressure (Psub) 60%

💨

Diaphragm

Diaphragma

The main muscle of inspiration. A dome shape that descends when it contracts, expanding the lungs. In singing, it controls expiratory flow to keep subglottal pressure steady.

⚡ Function: controls air pressure

🦴

Intercostals

Mm. intercostales externi / interni

The external ones expand the rib cage (inspiration). The internal ones compress it (active expiration). They work together with the diaphragm to regulate airflow.

⚡ Function: rib cage expansion/compression

💪

Abdominals

Mm. rectus abdominis, obliqui, transversus

Generate the positive pressure for active expiration. Essential for dynamic control of intensity and steady airflow in long phrases.

⚡ Function: main driver of subglottal pressure in singing

🏋️

Pelvic Floor

Diaphragma pelvis

Provides the lower base for the abdominal pressure system. Acts as a counterpoint to the diaphragm, stabilizing the air column.

⚡ Function: lower anchor of the pressure system

🔴

Thyroarytenoid (TA)

M. thyroarytenoideus

Forms the body of the vocal fold. When it contracts it shortens and thickens the folds, increasing vibrating mass. Dominant in chest register.

⚡ Shortens + thickens → ↓ F0 → chest register

🔵

Cricothyroid (CT)

M. cricothyroideus

Tilts the thyroid cartilage toward the cricoid, stretching and thinning the vocal folds. The main regulator of fundamental frequency.

⚡ Stretches + thins → ↑ F0 → head/falsetto register

🟠

Lateral Cricoarytenoid (LCA)

M. cricoarytenoideus lateralis

Rotates the arytenoids medially, closing the front portion of the glottis. Essential for an efficient glottal closure during phonation.

⚡ Anterior adduction → efficient glottal closure → less breathy sound

🟤

Interarytenoids (IA)

Mm. arytenoidei (transverso + oblicuo)

Bring the arytenoids together, closing the back portion of the glottis. Complement LCA action for a complete closure.

⚡ Posterior adduction → removes posterior gap → ↓ breathiness

🟢

Posterior Cricoarytenoid (PCA)

M. cricoarytenoideus posterior

The ONLY abductor muscle of the larynx. Opens the vocal folds for breathing. Its paralysis is a medical emergency.

⚡ Abduction → opens the glottis → breathing

⬆️

Suprahyoid muscles

Digástrico, Milohioideo, Genihioideo, Estilohioideo

Raise the larynx and hyoid bone. Excessive tension in them is a common cause of vocal fatigue and constriction. Vocal technique aims for their controlled relaxation.

⚡ Raise the larynx → shorten the vocal tract → brighter timbre

⬇️

Infrahyoid muscles

Esternohioideo, Omohioideo, Esternotiroideo, Tirohioideo

Lower the larynx. They lengthen the vocal tract, darkening the timbre and potentially enabling freer phonation. The “low larynx” of classical technique.

⚡ Lower the larynx → lengthen the tract → darker/richer timbre

🛡️

Thyroid Cartilage

Cartilago thyroidea

The larynx’s front “shield” (forms the Adam’s apple). The anterior attachment point of the vocal folds. Its tilt via CT is key to pitch control.

⚡ Anterior anchor point for the vocal folds

💍

Cricoid Cartilage

Cartilago cricoidea

A complete ring forming the base of the larynx. Articulates with the thyroid (cricothyroid joint) and the arytenoids. The only complete cartilaginous ring.

⚡ Structural base of the whole laryngeal system

🎯

Arytenoid Cartilages

Cartilagines arytenoideae

A pair of pyramid-shaped cartilages where the vocal folds attach posteriorly. Their rotating and gliding movements control glottal adduction/abduction.

⚡ Control point for glottal opening/closing

🍃

Epiglottis

A leaf-shaped cartilage that protects the airway during swallowing. In singing, its configuration with the arytenoids forms the “epilaryngeal tube” that generates the singer’s formant.

⚡ Shapes twang / the singer’s formant (~2800–3400 Hz)

Want to see this applied to your own voice?

Analyze your voice