The application of nonlinear phonological theory to intervention with phonologically delayed twins

Despite the fact that speech-language pathologists do not develop the theories underlying the principles and procedures used in the clinic, speech and language clinicians are ethically obliged to apply the "best" possible theory in their practice. Recently phonologists have been developing a theory of nonlinear phonology. Application of this theory to cross-linguistic data and to child language data has shown that what appeared to be idiosyncratic or difficult to account for using previous theoretical formulations can be neatly explained using a nonlinear phonological explanation. The purpose of this study was to investigate the possibility of further extending the application of nonlinear phonological principles to the field of speech-language pathology. Two levels defined by the theory, segmental and prosodic, were investigated in a six-month-long intervention programme with a set of phonologically delayed twins (aged 5;6 at the outset of the project). Each twin was assigned to an experimental condition motivated by one of these levels, or tiers. In each condition, intervention goals were determined by parameters of the theory; the segmental condition contrasted features "higher" versus "lower" in the feature hierarchy, while the prosodic condition contrasted moraic with onset-rime descriptions of syllable/word shape. Using twins as subjects also allowed the twin aspect of language acquisition and speech-language intervention to be explored. Results of the phonological intervention study revealed that nonlinear phonology provides a viable framework for assessing and determining goals for phonological remediation. A comparison of progress in therapy indicated that one twin acquired therapy goals faster than the other. An investigation of the differential progress of the twins allowed conclusions to be drawn regarding social awareness and success in phonological therapy.Medicine, Faculty ofAudiology and Speech Sciences, School ofGraduat