Intonation contour realisation for Standard Yorùbá text-to-speech synthesis:a fuzzy computational approach

This paper presents a novel intonation modelling approach and demonstrates its applicability using the Standard Yorùbá language. Our approach is motivated by the theory that abstract and realised forms of intonation and other dimensions of prosody should be modelled within a modular and unified framework. In our model, this framework is implemented using the Relational Tree (R-Tree) technique. The R-Tree is a sophisticated data structure for representing a multi-dimensional waveform in the form of a tree. Our R-Tree for an utterance is generated in two steps. First, the abstract structure of the waveform, called the Skeletal Tree (S-Tree), is generated using tone phonological rules for the target language. Second, the numerical values of the perceptually significant peaks and valleys on the S-Tree are computed using a fuzzy logic based model. The resulting points are then joined by applying interpolation techniques. The actual intonation contour is synthesised by Pitch Synchronous Overlap Technique (PSOLA) using the Praat software. We performed both quantitative and qualitative evaluations of our model. The preliminary results suggest that, although the model does not predict the numerical speech data as accurately as contemporary data-driven approaches, it produces synthetic speech with comparable intelligibility and naturalness. Furthermore, our model is easy to implement, interpret and adapt to other tone languages.

A computational model of intonation for yorùbá text-to-speech synthesis:design and analysis

In this paper we present the design and analysis of an intonation model for text-to-speech (TTS) synthesis applications using a combination of Relational Tree (RT) and Fuzzy Logic (FL) technologies. The model is demonstrated using the Standard Yorùbá (SY) language. In the proposed intonation model, phonological information extracted from text is converted into an RT. RT is a sophisticated data structure that represents the peaks and valleys as well as the spatial structure of a waveform symbolically in the form of trees. An initial approximation to the RT, called Skeletal Tree (ST), is first generated algorithmically. The exact numerical values of the peaks and valleys on the ST is then computed using FL. Quantitative analysis of the result gives RMSE of 0.56 and 0.71 for peak and valley respectively. Mean Opinion Scores (MOS) of 9.5 and 6.8, on a scale of 1 - -10, was obtained for intelligibility and naturalness respectively.

Early hearing loss and language abilities in children with Down syndrome

BACKGROUND: Although many children with Down syndrome experience hearing loss, there has been little research to investigate its impact on speech and language development. Studies that have investigated the association give inconsistent results. These have often been based on samples where children with the most severe hearing impairments have been excluded and so results do not generalize to the wider population with Down syndrome. Also, measuring children's hearing at the time of a language assessment does not take into account the fluctuating nature of hearing loss in children with Down syndrome or possible effects of losses in their early years. AIMS: To investigate the impact of early hearing loss on language outcomes for children with Down syndrome. METHODS & PROCEDURES: Retrospective audiology clinic records and parent report for 41 children were used to categorize them as either having had hearing difficulties from 2 to 4 years or more normal hearing. Differences between the groups on measures of language expression and comprehension, receptive vocabulary, a narrative task and speech accuracy were investigated. OUTCOMES & RESULTS: After accounting for the contributions of chronological age and nonverbal mental age to children's scores, there were significant differences between the groups on all measures. CONCLUSIONS & IMPLICATIONS: Early hearing loss has a significant impact on the speech and language development of children with Down syndrome. Results suggest that speech and language therapy should be provided when children are found to have ongoing hearing difficulties and that joint audiology and speech and language therapy clinics could be considered for preschool children.