Anatomical Structures

The vocal tract is bounded by hard and soft tissue structures. These structures are either essentially immobile (such as the hard palate and teeth), or are movable. The movable structures associated with speech production are also referred to as articulators. The tongue, lips, jaw, and velum are the primary articulators; movement of these articulators appears to account for most of the variation in vocal tract shape associated with speaking. However, additional structures are capable of motion as well. For instance, the glottis can be moved up or down to shorten or lengthen the vocal tract. A downward motion of the glottis while the oral and nasal cavities are occluded can produce the negative pressure in the vocal tract needed for the implosive sounds of some languages.