Using 99 images of rhesus macaque vocal tracts from the X-rays, these researchers simulated the three-dimensional space in the monkey mouth and throat. By mapping the flow of air through this space, the scientists generated a hypothetical range of speech sounds that monkeys could produce. The “phonetic potential” of a macaque, they concluded, was eight times larger than estimated in 1969.
The scientists generated the phrase “Will you marry me?” as if spoken by macaque. The words are odd and clipped, but the authors argued it sounds as comprehensible as English with a slight “foreign accent.” (Less charitably it sounds like Gollum, from “The Lord of the Rings,” trying to speak through a chokehold.) Crucially, the models showed the macaques were capable of vowel sounds, as in “bat,” “bet,” “bit,” “but” and “bought.”