Jo Estill

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 in this website will only give a small 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:

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 connection 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 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. 

Click to hear Speech Quality

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

Click to hear Sob Quality

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

Click to hear Twang Quality

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

Click to hear Opera Quality

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.

Click to hear Falsetto Quality

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.

Click to hear Belt Quality


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.


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