LEXICAL AND POST-LEXICAL PITCH FEATURES IN IṢẸKÍRÌ OF DELTA STATE, NIGERIA

Abstract

Pitch, a vital factor in the determination of tone, stress and intonation, which places utterances on a scale ranging from low to high, is an important feature of Iṣẹkírì, a Yoruboid language. Extant studies on Iṣẹkírì, have largely been on the syntax and segmental phonology, with little attention paid to the pitch variations of its tone and intonation. This study was, therefore, designed to examine tone and intonation in Iṣẹkírì, with a view to determining the nature of the tonal system, the mechanisms employed in the realisation of tonal contours, and the interaction of tone and intonation. The study adopted Acoustic Phonetic Approach and Optimality Theory as the framework. The ethnographic design was employed. Data were elicited from 17 native speakers (10 males and seven females) purposively selected for their proficiency in Iṣẹkírì and duration of stay in three near homogenous communities: Abigborodo (6), Gbokoda (6) and Gbodo (5). Digital recordings of elicited and natural conversation of speech were converted to .wav format. Each measurement provided five tokens of each item of the paradigms. Data were subjected to statistical and philological analyses. Iṣẹkírì has a three-way contrastive pitch system comprising High (H), Mid (M) and Low (L) tones. The mid tone is in asymmetry to high and low tones. Tone asymmetry is adequately accounted for by the constraint hierarchy MAX[H]>>*H↔M, *M↔H, *L↔H, *M↔L >> MAX[L] >>*MULTIPLE>> MAX[M]. Tonological operations include Leftward High Tone Spread and Rightward High Tone Spread (RHTS). The RHTS is sensitive to tone type and number of syllables with a tonal melody of LL or LLL. The F0 mechanisms of declination, final lowering and downstep define contour formations. Declination significantly affects mid and low tones, but not the high tone, which has a better fit of regression model (R2 =0.9) and a -0.678 regression line slope. Boundary tones used to distinguish declaratives from different question types are 0% for statement intonation and L% for question intonation. Contrary to cross-linguistic evidence, the Iṣẹkírì polar question shows a final fall in pitch, which occurs late in the utterance and a lack of suspension of downstep. There is a consistent effect of initial pitch-raising in Yes/No questions, which is accompanied by final syllable lengthening and increased acoustic intensity. Complex declaratives show a partial pitch reset at the left edge of an embedded ι-phrase. The intonational phrase, which is marked by a pause and pitch reset, is the only unit above the prosodic word. Underlying lexical tones are not affected by intonation with the exception of sentence-final tones of the question intonation. The falling intonation pattern is used across sentences. Tone-intonational strategies include partial submission and avoidance. Falling intonation in polar questioning and zero boundary tone for statements are diagnostic patterns of Iṣẹkírì of Delta State. The language also operates downstep, bidirectional tone spreading and partial submission in its prosodic phonology