What is so significant about the hyoid bone, especially in regards to speech production?

     The hyoid bone is located on the anterior (face side) side of the neck in front of the third vertabra, just above the lump of cartilage known as the Adam's apple.  The hyoid bone is very interesting in that it is the only bone in the human body that is not connected to any other bones.  Wikipedia summarizes the function of the hyoid bone nicely while also adding some insight to the question at hand:

  “The hyoid bone is present in many mammals, it allows a wider range of tongue, pharyngeal and laryngeal movements by bracing these structures alongside each other in order to produce variation.[4] Its descent in living creatures is not unique to Homo sapiens, and does not allow the production of a wide range of sounds: with a lower larynx, men do not produce a wider range of sounds than women and 2 year old babies. Moreover the larynx position of Neanderthal was not a handicap to producing speech sounds.[5] The discovery of a modern-looking hyoid bone of a Neanderthal man in the Kebara Cave in Israel led its discoverers to argue that the Neanderthals had a descended larynx, and thus human-like speech capabilities.[6] However, other researchers have claimed that the morphology of the hyoid is not indicative of the larynx's position.[7] It is necessary to take into consideration the skull base, the mandible and the cervical vertebrae and a cranial reference plane.[8][9]”

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