Intonation Patterns in Yoruba Questions: An Acoustic Phonetic Investigation

The prosodic structure of questions in tone languages presents a significant theoretical challenge, as the communicative functions of intonation must be negotiated alongside the lexical and grammatical functions of tone. This study investigates intonation patterns in Yoruba questions, examining the acoustic correlates of interrogative prosody in a language where tone is phonemically contrastive at the lexical level. Using instrumental acoustic phonetics methodology, productions of yes-no questions, wh-questions, and echo questions were elicited from 30 native Yoruba speakers in Ibadan, Oyo State, South West Nigeria, and analysed using Praat software for fundamental frequency, duration, and intensity measurements. The study applies autosegmental-metrical phonology and typological prosody theory to interpret the acoustic data. Existing research on Yoruba prosody has focused primarily on lexical tone, with the suprasegmental marking of question intonation receiving very limited systematic acoustic treatment. This study fills that empirical phonetic gap. The research investigates how Yoruba speakers mark yes-no questions versus statements given the constraints of lexical tone, whether final boundary tones or pre-nuclear pitch accents carry question marking, and how tonal coarticulation affects question prosody across different tonal environments. Findings are expected to reveal that Yoruba questions are marked through a combination of final particle usage and subtle boundary tone modifications rather than through the dramatic intonation rises characteristic of English questions. Recommendations will address acoustic phonetic pedagogy for Yoruba and the development of Yoruba speech technology resources. Keywords: intonation, Yoruba questions, acoustic phonetics, prosody, tone language.