Abstract: A solution for text-to-speech conversion is provided. According to the solution, it is checked whether or not a character string comprises a character combination which does not represent a word. If the character string comprises a character combination which does not represent a word, the function of the character combination is analyzed. Based on the analysis, a speech synthesizer is configured to produce a desired speech waveform.

Abstract: In a speech recognition environment where time constraint limits the use of stored grammars in matching with a speech, the phonemes converted words are built into a number of trees of different priority levels so that the number of the trees combined into a concatenated tree for speech recognition is based at least partly on the time constraint. The trees of a lower priority level are used only when the time constraint allows such use and the trees of a higher priority level are used at least partly prior to the trees of a lower priority level being used.