irteenth-century theory of speech.

This historical paper examines a pioneering theory of speech production and perception from the thirteenth century. Robert Grosseteste (c.1175—1253) was a celebrated medieval thinker, who developed an impressive corpus of treatises on the natural world. This paper looks at his treatise on sound and phonetics, De generatione sonorum [On the Generation of Sounds]. Through interdisciplinary analysis of the text, this paper finds a theory of vowel production and perception that is notably mathematical, with a formulation of vowel space rooted in combinatorics. Specifically, Grosseteste constructs a categorical space comprising three fundamental types of movements pertaining to the vocal apparatus: linear, circular, and dilational-constrictional; these correspond to similarity transformations of translation, rotation, and uniform scaling, respectively. That Grosseteste's space is categorical, and low-dimensional, is remarkable vis-a-vis current theories of phoneme perception. As well as his description of vowel space, Grosseteste also sets out a hypothetical framework of multisensory integration, uniting the production, perception, and representation in writing of vowels with a set of geometric figures associated with “mental images.” This has clear resonances with contemporary studies of motor facilitation during speech perception and audiovisual speech. This paper additionally provides an experimental foray, illustrating the coherence of mathematical and scientific thinking underpinning this early theory.