The paper deals with the recognition of digits and with the hybrid recognition technology. By the hybrid approach, we assume the combination of two or more different recognizers have to achieve higher recognition accuracy. Two Lithuanian recognizers using the word based and phonemebased hidden Markov models (HMM) together with the Spanish language recognizer 8.0 (Spanish-US) and Microsoft Speech Server Spanish language recognizer 9.0 (Spanish-US) were investigated. Using data mining package Weka, classification research was carried out with five different recognizer combining scenarios. The results of connecting two or three recognizers showed that the suggested method of using machine learning method to connect different recognizers greatly improved the recognition accuracy of digits speech corpus in all five cases. Manual annotation of the part of speech corpus enables to increase the recognition accuracy of Lithuanian digits names about 40 % using sub-word-based recognizer. SAMPA_LT set of phonemes is redundant for the digits recognition.

This paper presents the recently developed medical-pharmaceutical informative system with voice user interface. This is the first computerized system oriented towards healthcare services and industry where Lithuanian voice commands are used as a primary mean for control. Another essential property of the developed system is its hybrid nature: two different recognizers -an adapted commercial Spanish speech recognizer available from Microsoft and a locally developed HMM speech recognizer based on Lithuanian acoustic models -are operating in parallel. The recognition hypotheses produced by those recognizers are joined together using logical rules obtained using decision rules induction algorithms such as Ripper. All these measures and approaches allowed achieve very high speaker independent voice commands recognition accuracy acceptable for the system implementation in practice. The best achieved recognition was 98.9 % for 1000 Lithuanian voice commands. The paper presents optimization issues related with the development of the system.

Paper deals with application of Microsoft Office Communications Server Speech Server or MSS'2007 for Lithuanian voice commands recognition. Voice servers together integrate telephony, speech and internet providing tools for developing applications that run over a telephone. Using of transcriptions of Lithuanian words so far is the only solution of voice servers' application for Lithuanian language. The results of investigation of Lithuanian digit names recognition by German, English, French and Spanish speech recognition engines implemented on MSS'2007 are presented. The best accuracy of Lithuanian digit names and voice commands recognition was achieved by Spanish recognizer. Achieved recognition accuracy is suitable for the real applications of speech server for Lithuanian language.

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