Phonation has slightly different meanings depending on the subfield of phonetics. Among some phoneticians, phonation's the process by which the vocal folds produce certain sounds through quasi-periodic vibration. This's the definition used among those who study laryngeal anatomy and physiology and speech production in general. Other phoneticians, though, call this process quasi-periodic vibration voicing, and they use the term phonation to refer to any oscillatory state of any part of the larynx… (More on Phonation)