Estill Voice Training (often abbreviated EVT) is a program for developing vocal skills based on analysing the process of vocal production into control of specific structures in the vocal mechanism. By acquiring the ability to consciously move each structure the potential for controlled change of voice quality is increased.

The system was established in 1988 by American singing voice specialist Jo Estill, who had been researching in this field since 1979. Estill's research led to a series of vocal manoeuvres to develop specific control over individual muscle groups within the vocal mechanism. Soto-Morettini quotes Estill as saying the great strength of her method is that it can be used for any style of music, and speech and language therapists describe the exercises as valuable to voice therapy as well as singing, in both professional and non-professional voice use, offering an approach for therapeutic intervention. Estill Voice Training is a trademark of Estill Voice International, LLC.

Power, source and filter: Estill Voice Training partitions the vocal system into the three components power, source and filter extending the existing source–filter model of speech production. "Power" is the source of energy producing the sound (typically the respiratory system causing air to be expelled from the lungs). "Source" is the component that vibrates to create the sound waves (the vocal folds). "Filter" is the shaping of the sound waves to create the final result (the vocal tract). The focus of Estill Voice Training is on the source and filter components of the vocal system and the interactions between them.

Craft, artistry and performance magic: Estill Voice Training separates the use of voice into the "craft" of having control over the vocal mechanism, the "artistry" of expression relative to the material and context, and the "performance magic" of a speaker or singer connecting with their audience. Estill Voice Training has a focus on the "craft" aspect and hence has also been known as "Estill voice craft" by some practitioners.

Effort levels: Estill Voice Training uses the identification and quantification of the level of work or 'effort' required for speaking and singing to help develop kinesthetic feedback. This approach enables a speaker or singer to recognize, locate and control the degree of effort involved in voice production.

Dynamical systems theory and attractor states: The human vocal system is extremely complex, involving interactions between breath flow, moving structures, resonators and so on. Estill Voice Training draws on a branch of applied mathematics known as dynamical systems theory that helps to describe complex systems. One key concept Estill Voice Training takes from dynamical systems theory is the notion that complex systems can have attractor states. Attractor states are states to which a complex system tends towards, or is attracted to, over time. When applied to the human vocal system, Estill Voice Training proposes there are configurations of the vocal system that are attractor states, which the speaker or singer uses habitually or tend towards. For example, a subject whose attractor state is for their velum (also known as the soft palate) to be in a raised position may find it requires more conscious effort to create a nasal sound than someone else whose attractor state is for their velum to be in the lowered position.

In Estill Voice Training there are thirteen vocal exercises or "figures for voice" (named after the "compulsory figures" that figure skaters use to demonstrate proficiency). Each exercise or "figure" establishes control over a specific structure of the vocal mechanism, in isolation, by moving the structure through a number of positions. For example, the figure for velum (soft palate) control involves moving the velum through raised, partially lowered and lowered positions. The thirteen Figures for Voice are:

These figures for voice exercises have a focus basic anatomy and vocal physiology, a knowledge of which helps encourage deductions on reducing constriction and healthy voice decisions. Janice Chapman, the operatic singer, voice teacher and researcher, writes "Estill figures lead to a much greater freedom and flexibility in the demanding work of the singer and actor."