The interaction of two types of modality of a system for processing audiovisual information in the problem of evaluating the emotional state of users of dialogue information systems was studied. In order to enhance the precision of an estimation in real time, it is proposed to use an audio modality for the purpose of detecting speech segments of increased emotionality. As an indicator of the degree of speech emotionality, the intensity of the flow of vowel sounds in a user’s speech signal at input to the information system is used. A method has been developed for measuring this indicator from the empirical probability of the occurrence of vowel sounds in the user’s a speech signal. An example is presented for practical implementation of the method in soft real time. A full-scale experiment using the authors’ software was posed and presented. The advantages of the proposed method are shown: high speed of operation and high sensitivity to the change in the level of speech emotionality of users. Results obtained are intended for developers of advanced information systems with an audiovisual user interface.