page_title: Origin of speech
section_title: Tongue
hierarchical_section_title: Origin of speech / Evolution of the speech organs / Tongue
context_page_description: The origin of speech refers to the more general problem of the origin of language in the context of the physiological development of the human speech organs such as the tongue, lips and vocal organs used to produce phonological units in all human languages.
context_section_description: The word "language" derives from the Latin lingua, "tongue". Phoneticians agree that the tongue is the most important speech articulator, followed by the lips. A natural language can be viewed as a particular way of using the tongue to express thought.
  The human tongue has an unusual shape. In most mammals, it is a long, flat structure contained largely within the mouth. It is attached at the rear to the hyoid bone, situated below the oral level in the pharynx. In humans, the tongue has an almost circular sagittal (midline) contour, much of it lying vertically down an extended pharynx, where it is attached to a hyoid bone in a lowered position. Partly as a result of this, the horizontal (inside-the-mouth) and vertical (down-the-throat) tubes forming the supralaryngeal vocal tract (SVT) are almost equal in length (whereas in other species, the vertical section is shorter). As we move our jaws up and down, the tongue can vary the cross-sectional area of each tube independently by about 10:1, altering formant frequencies accordingly. That the tubes are joined at a right angle permits pronunciation of the vowels [i], [u] and [a], which nonhuman primates cannot do. Even when not performed particularly accurately, in humans the articulatory gymnastics needed to distinguish these vowels yield consistent, distinctive acoustic results, illustrating the quantal nature of human speech sounds. It may not be coincidental that [i], [u] and [a] are the most common vowels in the world's languages. Human tongues are a lot shorter and thinner than other mammals and are composed of a large number of muscles, which helps shape a variety of sounds within the oral cavity. The diversity of sound production is also increased with the human’s ability to open and close the airway, allowing varying amounts of air to exit through the nose. The fine motor movements associated with the tongue and the airway, make humans more capable of producing a wide range of intricate shapes in order to produce sounds at different rates and intensities.
caption: Spectrogram of American English vowels [i, u, ɑ] showing the formants f1 and f2
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