In articulatory phonetics, the place of articulation (also point of articulation) of a consonant is a location along the vocal tract where its production occurs. It is a point where a constriction is made between an active and a passive articulator. Active articulators are organs capable of voluntary movement which create the constriction, while passive articulators are so called because they are normally fixed and are the parts with which an active articulator makes contact. Along with the manner of articulation and phonation, the place of articulation gives the consonant its distinctive sound. Since vowels are produced with an open vocal tract, the point where their production occurs cannot be easily determined. Therefore, they are not described in terms of a place of articulation but by the relative positions in vowel space. This is mostly dependent on their formant frequencies and less on the specific tongue position and lip rounding. The terminology used in describing places of articulation has been developed to allow specifying of all theoretically possible contrasts. No known language distinguishes all of the places described in the literature so less precision is needed to distinguish the sounds of a particular language. Overview The human voice produces sounds in the following manner: Air pressure from the lungs creates a steady flow of air through the trachea (windpipe), larynx (voice box) and pharynx (back of the throat). Therefore, the air moves out of the lungs through a coordinated action of the diaphragm, abdominal muscles, chest muscles and rib cage. The vocal folds in the larynx vibrate, creating fluctuations in air pressure, known as sound waves. Resonances in the vocal tract modify these waves according to the position and shape of the lips, jaw, tongue, soft palate, and other speech organs, creating formant regions and so different qualities of sonorant (voiced) sound. Mouth radiates the sound waves into the environment. Nasal cavity adds resonance to some sounds such as and to give nasal quality of the so-called nasal consonants. The larynx The larynx or voice box is a cylindrical framework of cartilage that serves to anchor the vocal folds. When the muscles of the vocal folds contract, the airflow from the lungs is impeded until the vocal folds are forced apart again by the increasing air pressure from the lungs. The process continues in a periodic cycle that is felt as a vibration (buzzing). In singing, the vibration frequency of