Informatica

One of the components of the text-to-speech synthesis system is the database of sounds. Two Lithuanian diphone databases in the MBROLA format are presented in this paper. The list of phonemes and the list of diphones necessary for Lithuanian text-to-speech synthesis are described. The problem of phoneme combinations that are not used in the Lithuanian language is dealt with in the work. Also, the article is concerned with transcribing a Lithuanian text.

Phoneme duration modelling is one of the stages in prosody modelling for text-to-speech systems. The rule-based phoneme duration model proposed by Klatt (1979) is still quite a popular method. One of the main shortcomings of this method is that the values of the parameters are selected in an experimental way. This work proposes a new iterative algorithm for the automatic estimation of the factors for the Klatt model using the corpus of an annotated audio record of the speaker. The phoneme duration models were built for three different Lithuanian speakers. The quality of the estimation of phonemes durations was evaluated by the root mean square error, the mean absolute error and the correlation coefficient.

The paper deals with automatic stressing of the Lithuanian text. In the previous work the author presented an algorithm for automatic stressing of the Lithuanian text on the basis of a dictionary. The aim of the present work is to improve the above mentioned algorithm by including formal stressing rules for nouns and adjectives. By means of these rules such words as diminutives, names and degrees of adjectives that are not present in the dictionary may be stressed. The work analyses when it is more convenient to formulate rules manually and when to generate them automatically. A method for formulating rules manually has been described and a set of such rules has been presented. Besides the algorithm for generating stressing rules with the help of a dictionary of stems of nouns and adjectives has been given.

This paper deals with one of the components of text-to-speech synthesis of Lithuanian language namely – text transcription. Formal rules' method is used for text transcription. In this work the suitability of this method is grounded, an analysis of the form of rules to fit is made and the set of rules and interpreting algorithm is presented. Contextual information, features of stress, syllable boundaries and softness are used in the rules.