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.
