Phonetic properties of chimpanzee, gorilla, and orangutan hoots tell a uniform story and point to new frontiers

We present a first–ever comparison of phonetic properties across vocalizations by great apes. We show that “hoot–like” calls by (males of) all non–human great ape genera – chimpanzees, gorillas, and orangutans – overlap with those of human back rounded vowels. Our work underlines the importance of studying the production of calls. Observations from both comparative vocal morphology (non–human great apes have short–and–narrow pharynges and tongues contained in the oral cavity) and observations of vocalizing animals indicate they likely achievethese qualities desperately.