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　　The human voice is capable of forming a plethora¹ of incredibly different sounds. So many, in fact, that each individual language contains only a subset of potential sound units or phonemes. What factors determine whether a phoneme enters coming in use or relegated² to silence? It turns out geography may play a role. One phoneme that occurs in only 20 percent of the world's languages is the ejective consonance such as Aah or KAh.  Caleb Elvin, an anthropologist³ at the University of Miami, decided⁴ to map where the sound occurs. He took a sample of 567 languages spoken around the world and compares the locations and the attitudes of those either contained or ignored the ejective consonance. Elvin discovered that languages that includes the ejective consonance will generally spoken at a higher elevation⁵ than those that not. His research is in the journal of Plos One. Elvin suggests that sounds are more popular at the altitude because lower air pressure may make it easier to produce the burst of air that is the key characteristic of ejective consonance which is Pretty Cool.