The organs of speech are located in the mouth and throat. During speech, air pushed out from the lungs through the larynx and epiglottis vibrates the vocal cords, producing a continuous tone whose pitch can be changed by varying the shape of the larynx. Consonants, modified by the tongue and lips, are formed when air is emitted suddenly or when it is cut off firmly. Voice production occurs in the larynx. During breathing the vocal cords are held apart, but as speech commences, the cartilages of the larynx are drawn together by the action of muscles and a "chink" is created. The tension of the vibrating cords, changed by the tilting of the cartilages, alters the pitch of the spoken sound. High notes are produced by the vibration of tight vocal cords and low notes are produced by vibrating loose cords http://www.youtube.com/watch?v=C2lRhe_Fc04