Abstract:
Bilingual aphasia, an acquired language disorder in which individuals exhibit parallel impairment in the different modalities of speech in two languages, is a major global public health issue. Extant phonological studies on aphasia in Nigeria have focused mainly on the description of segmental and prosodic features of spoken English in bilingual aphasics, with scant attention paid to the description of their sound patterns in local languages. This study was, therefore, designed to examine the phonology of Yoruba-English Broca’s aphasics, with a view to determining their phonological processes and language preference.
Noam Chomsky and Morris Halle’s Generative Phonology was adopted as the framework, while the descriptive design was used. Twelve Nigerian Yoruba-English Broca’s aphasics were purposively selected from the University College Hospital, Ibadan, based on their availability and suitability. Unstructured interviews were conducted with the aphasics using culture-related drawings that depict different aspects of a typical Nigerian traditional and social life. The data were subjected to phonological analysis.
The articulation deficits of the participants revolved around substitution, deletion, and insertion. Substitution patterns involve fricative stopping, in which the voiceless alveolar fricative [s] was consistently substituted with the voiceless alveolar plosive [t]. Both segments differ in their manner of articulation features. While [t] is [-continuant], [s] is [+continuant]. Lateralisation of approximant was also common with the substitution of [l] for [r]. The two segments differ in their manner of articulation features. While [r] is [-lateral], [l] is [+lateral]. Backing of alveolar manifested in the substitution of [f] for [s] where a [-labial] replaced a [+labial]. Lowering and backing of vowels were exhibited in the substitution of [i] for [u] or [a], where [i] is [+high] [-back], [u] is [+back], and [a] is [-high]. Deletion of a segment was common with palato-alveolar affricate [ʤ] in word-initial position, #[+del rel] Ø and alveolar nasal [n] in word medial positions, －[+nasal]－ Ø. Simplification of complex segments manifested mainly in doubly articulated sounds such as [k͡p] and [g͡b]. Insertion was noticeable in Yoruba words which begin with mid-front vowels [e] and [ԑ], where #[+syll] is realised as #[+cons]. The lack of certain segments which are present in English but absent in Yoruba often induced interference in the speech of these bilingual aphasics, even in their pre-morbid stage. Such segments are voiced labiodental fricative [v], voiced alveolar fricative [z], schwa [ə] and cuneiform [ʌ]. In describing the culture-related drawings, the participants showed a preference for the Yoruba language when compared with English. They expressed more enthusiasm as they engaged in diverse conversations using the Yoruba language.
The speech of the selected Yoruba-English Broca’s aphasics in the University College Hospital, Ibadan is dominated by substitution, deletion, and insertion, and they exhibited a preference for spoken Yoruba instead of English. Caregivers and rehabilitation experts should, therefore, consider the linguistic background of the aphasics in determining treatment protocol.
