Humans have a unique anatomy that supports our ability to produce complex language. The elastic recoil of the lungs provides the necessary acoustic energy, while the diaphragm, intercostal muscles, and abdominal muscles manipulate how that air is released through the larynx, a complex structure that houses the vocal cords, and the supralaryngeal vocal tract (SVT), which includes the oral cavity and the pharynx, the cavity behind the mouth and above the larynx.
When air from the lungs rushes against and through the muscles, cartilages, and other tissue of the vocal cords, they rapidly open and close to produce what’s known as the fundamental frequency of phonation (F0), or the pitch of a speaker’s voice. The principal sounds that form words—known as formant frequencies—are produced by changes to the positions of the lips, tongue, and larynx.
In addition to the anatomy of the SVT, humans have evolved increased synaptic connectivity and malleability in certain neural circuits in the brain important for producing and understanding speech. Specifically, circuits linking cortical regions and the subcortical basal ganglia appear critical to support human language.
The article’s a good read.