(Click to enlarge)Vocal tract is the cavity which produces voice. Human vocal tract is said to be unique from that of all other animals. Human language from all aspects remains quite unique. The adjoining diagram shows a vocal tract, we all share. As the primary medium of language is speech, historically and quantitatively (e.g. about 6000 languages are not written, but spoken), so is the vocal tract important.
* Source of the image: http://en.wikipedia.org/wiki/Vocal_tract
