Title:   MOTOR-PROSODIC PLANNING AND INTONATION IN DISORDERED NIGERIAN ENGLISH SPEECH

Abstract
Intonation performs a central role in spoken communication by indicating sentence type, the intention of the speaker, and discourse meaning. In Nigerian English, intonation is shaped by interaction with native tonal languages, resulting in patterns that are markedly different from those of native-speaker varieties of English. While numerous studies have examined Nigerian English intonation in non-clinical populations, relatively little attention has been paid to how it is realised in disordered Nigerian English speech. This study examines sentence-level intonation in disordered Nigerian English speech within the framework of Motor-Prosodic Planning Theory with a view to determining the extent of preservation of or damage to motor-prosodic routines. Using regulated sentence-reading tasks containing declarative statements, wh-questions and yes-no questions, speech data were purposively elicited from thirty-five Nigerians with acquired and developmental language disorders from clinical and educational locations. Frequency counts, percentage distributions complemented with bar chart substantiated the motor-theoretical analysis. The findings reveal that falling intonation is the most frequently realised overall pattern, with a strong concentration in declarative statements, indicating partial preservation of default, low-complexity motor-prosodic routines. In contrast, wh-questions exhibit a high incidence of obscure intonation patterns, indicating substantial disruption in the motor planning of interrogative prosody. Yes-no questions have a more varied distribution, with rising intonation occurring frequently, with the use of level and falling intonation being significant, indicating unstable performance of pitch-raising gestures. Across all sentence types, obscure and level intonation patterns are used frequently, signalling diminished pitch modulation and poor control of tone. The results indicate that although some intonation patterns are preserved in disordered Nigerian English speech, there is a challenge in mapping prosodic representations to motor plans, especially in the motorically complex interrogative contexts. The research draws attention to the importance of motor-prosodic planning deficits in accounting for intonation deficits in disordered Nigerian English speech and the diagnostic potential of intonation. It provides empirical evidence to the emerging body of research on prosodic impairment in disordered speech in multilingual settings.
Keywords: Sentence-level intonation; Language disorders; Nigerian English Prosody; Disordered phonology; Clinical phonology

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Publication Date: 2026-08-19