The book presents original research into human vocal production, arguing for a duality of vocal sources including the esophagus and its vocal cords, and combines anatomical observation, introspective methods, and practical experiments. It examines mechanics of breathing, tongue and diaphragmatic movements, and the physiology underlying speech, singing, stuttering, and phonographic recording. It traces connections between vocal habits and national speech traits, comparing idiomatic expression and breathing patterns across languages, and discusses rhythm, stress, and schools of singing. Interleaved with methodological reflections and demonstrations, the text aims to translate inner experience into measurable principles of voice and vocal utterance.