Jo Estill is a New York based Speech Pathologist who has taken an extremely detailed look at all parts of the human vocal anatomy, and has engineered a singing and phonation (talking) technique called:

The Estill Voice Model

Jo Estill is proficient in three main areas of vocal expertise: Performance, Voice Science and Education. She has over 25 years of research in vocal physiology, acoustics, and perception of voice quality and has been published in many international medical and singing journals. She has taught voice for over 30 years at University and professional level, and has extensive touring and educational experience worldwide.

The information contained on this Web site will only give a remote glimpse into some of the methodology that Jo Estill has developed.

The Estill Voice Model is split into two levels.

The first level consists of a series of specific exercises that gives the student control over the 13 structures along the vocal tract - such as laryngeal tilt, vocal fold mass and pharyngeal width and length, etc. These are called The Compulsory Figures for Voice. When change occurs in one or more of these structures, a difference in vocal quality can be heard. The number of sound qualities at a singers command is dependant upon how many of these structures can be controlled.

The second level is called The Figure Combinations for Six Voice Qualities and this includes the specific structural “recipes” that result in Jo Estill’s six basic voice qualities: Sob, Twang, Falsetto, Opera, speech and belt.

Some of the terminology and concepts within the Estill Voice Model:

There are three main components that make up the voice as an instrument.

The lungs (the Power) Breath.

The Larynx (The Source) Vocal folds

The Vocal Tract (The Filter) The space from the vocal folds to the mouth including the nose and soft palate.

The relationship between the breath and the tone is called the Onset. You can have three possible onsets...

Glottal Onset - the vocal folds begin vibrating before the breath arrives, giving a hard vocal attack.

Aspirate Onset - the breath passes through the vocal folds before they begin to vibrate, giving a breathy sound.

Simultaneous Onset - breath and vibration occur at the vocal folds at the same time giving a balanced tone.

Other concepts which affect tone quality include:

Vocal Fold Mass - whether the folds are thick, thin or stiff.

Laryngeal Tilt - whether the larynx is relaxed, high or low.

Soft Palate Control - this will affect the degree of nasality in the sound.

Anchoring - the use of larger muscles, such as the neck, face and abdominal muscles, in order to support and direct tone quality.

Tongue Control - position of the tongue, whether high or low in the mouth, will alter tone significantly.

Vocal Fold Plane - the position of the front of the vocal folds in relation to the back of the vocal folds and the distance between them (the lengthening or shortening of the vocal folds).

Pharyngeal Length and Width - tone colour can be affected by making the tube at the top of the Larynx longer, shorter or wider,

The False Vocal Folds (or Vestibular Folds) are the fleshy mounds that sit just above the vocal folds. They can be open or closed and are involved naturally in constriction during swallowing, straining or coughing.

Constricted False folds constrict vocal tone.

Retracted False folds are the best for singing. This state allows full and free vocal expression.

The Six Voice Qualities

Speech Quality is the everyday sound heard when people talk. It is often used in Ballads, Rock music and in much of today’s contemporary music.    

Sob Quality is a low-Larynx, darker, softer vocal tone which often arouses empathy from the audience communicating passion, yearning, and heartfelt emotion.

Twang Quality is a high-Larynx, brighter, more harsh and nasal sound that is quite common in Country and Western music.

Opera Quality is a lower-Larynx combination of Sob and Speech vocal qualities giving a well anchored and powerful operatic vocal tone.

Falsetto Quality is a lighter, quieter, and generally breathier vocal quality, often heard in boy bands and boys choirs. It is often used in the upper register as it requires less effort to reach the notes.

Belt Quality is the biggest and loudest vocal quality and is often used in theatre and contemporary music today. It requires the most effort and muscular support if it is done correctly.

In her research, Jo Estill has developed a computerised spectrogram sound analysis program for use with the Estill Voice Model which can provide an accurate voiceprint for the purpose of monitoring and diagnosis. The following is a screen shot of the program, indicating the frequency bands involved with speech.

As previously mentioned the information on this web site is only grazing the surface of the very complicated and methodical system of vocal teaching. There is so much more available to learn and there are master teachers world-wide who continue to hold workshops and courses in the Estill Voice Model.

For further information, please refer to the Jo Estill Website:

The Singing Voice was created by Simon Chate. Email direct to: simon@thesingingvoice.com