Jan Gauffin was an early user of fiber optics which allowed him to discover that laryngeal structures above the glottal level are involved in speech. His research led him to postulate three independently controlled mechanisms: fundamental frequency control, glottal adduction/abduction, and laryngealization, the latter derived from the protective closure function. He argued that phonetic theory must be revised to account for the main phonation types of the world's languages. He saw them as combinations of two interacting dimensions: adduction/abduction and laryngealization. Secondly he gave the aryepiglottic sphincter an explanatory role in accounting for the production of low pitch and downward pitch inflections. During his lifetime his work received limited attention. However, later laryngoscopic research has confirmed and extended his thinking and findings. His contribution was a pioneering one.