Abstract.Computerized systems with voice user interfaces could save time and ease the work of healthcare practitioners. To achieve this goal voice user interface should be reliable (to recognize the commands with high enough accuracy) and properly designed (to be convenient for the user). The paper deals with hybrid approach implementation issues for the voice commands recognition. By the hybrid approach we assume the combination of several different recognition methods to achieve higher recognition accuracy. The experimental results show that most voice commands are recognized good enough but there is some set of voice commands which recognition is more complicated. In this paper the novel method is proposed for the combination of several recognition methods based on the Ripper algorithm. Experimental evaluation showed that this method allows achieve higher recognition accuracy than application of blind combination rule.

Paper presents research results obtained when building a speaker independent hybrid speech recognizer. This recognizer will be integrated as a phrase recognizer in a medical-pharmaceutical information system. The hybrid speech recognizer consists of two recognition components: an adapted commercial Microsoft Spanish speech recognizer and a locally developed hidden Markov models based recognizer implementing Lithuanian acoustic models. Efficiency of both recognition components was evaluated on multiple speaker independent speech recognition tasks. The average accuracy of Lithuanian recognizer was higher reaching 0.6% phrase error rate for user requests in medical-pharmaceutical domain. The adapted commercial Spanish speech recognizer showed the ability to improve the accuracy of Lithuanian recognizer in the worst recognition scenarios. These results proved the hypothesis formulated when proposing the basic idea of hybrid recognition approach: recognition errors from different recognizers built using various techniques are not strongly correlated. This fact could be exploited for improved overall speech recognition accuracy.

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.

This paper presents activities and challenges when implementing information processing technologies for people with hearing and visual impairments. Other than keyboard based input and monitor based for output modalities should be employed for this category of users. More important is that these modalities are crucial element for successful implementation of complex systems designed for disabled people. Some activities carried on in Lithuania implementing applications oriented for disabled people or using speech technologies and targeted to impaired people are presented too.

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