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Acoustic and perceptual properties of chimpanzee (<jats:italic>Pan troglodytes<\/jats:italic>) <jats:italic>hoo<\/jats:italic>\u2019s are similar to those of the human vowel \/u\/. However, the vocal tract morphology of chimpanzees likely limits their phonetic capabilities, so that it is unlikely, or even impossible, that their articulation is comparable to that of a human. To determine how qualities of the vowel \/u\/ may be achieved given the chimpanzee vocal tract, we calculated transfer functions of the vocal tract area for tube models of vocal tract configurations in which vocal tract length, length and area of a laryngeal air sac simulacrum, length of lip protrusion, and area of lip opening were systematically varied. The method described is principally acoustic; we make no claim as to the actual shape of the chimpanzee vocal tract during call production. Nonetheless, we demonstrate that it may be possible to achieve the acoustic and perceptual qualities of back vowels without a reconfigured human vocal tract. The results, while tentative, suggest that the production of <jats:italic>hoo<\/jats:italic>\u2019s by chimpanzees, while achieving comparable vowel-like qualities to the human \/u\/, may involve articulatory gestures that are beyond the range of the human articulators. The purpose of this study was to (1) stimulate further simulation research on great ape articulation, and (2) show that apparently vowel-like phenomena in nature are not necessarily indicative of evolutionary continuity per se.<\/jats:p>","DOI":"10.1007\/s10329-023-01107-3","type":"journal-article","created":{"date-parts":[[2023,12,18]],"date-time":"2023-12-18T19:03:00Z","timestamp":1702926180000},"page":"81-88","update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Sketches of chimpanzee (Pan troglodytes) hoo\u2019s: vowels by any other name?"],"prefix":"10.1007","volume":"65","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6739-0838","authenticated-orcid":false,"given":"Axel G.","family":"Ekstr\u00f6m","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jens","family":"Edlund","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"297","published-online":{"date-parts":[[2023,12,18]]},"reference":[{"key":"1107_CR1","unstructured":"Barreda S (2015) phonTools: functions for phonetics in R.\u00a0R package version 0.2\u20132.1"},{"issue":"1","key":"1107_CR2","doi-asserted-by":"publisher","first-page":"e0169321","DOI":"10.1371\/journal.pone.0169321","volume":"12","author":"LJ Bo\u00eb","year":"2017","unstructured":"Bo\u00eb LJ, Berthommier F, Legou T, Captier G, Kemp C, Sawallis TR et al (2017) Evidence of a vocalic proto-system in the baboon (Papio papio) suggests pre-hominin speech precursors. 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