Opera is a form of theatre developed in the late 16th century. Alongside with acting, dancing, set design and costume design, pronunciation is one of the main parts of the opera. Pronunciation and diction of the academic singers were analyzed in this paper by examining the perception of the research participants and their personal attitude concerning opera as a form of theatre. The results have shown that with the younger audiences, opera is not as popular as musical or drama. The lack of interest in that kind of music and incomprehensible pronunciation were stated as the reasons for before mentioned results. The analysis of the diction by examining the perception of the research participants in which each participant in average correctly transcribes 12 % of sound clips confirms the same statement. As expected, archaic words, unknown to the younger audiences, also had an impact on such result. Replacement of the plosives with nasals and approximant /v/ and vice versa was often, as well as replacement of the fricatives and affricates or voiceless and voiced consonants which only partially confirmed the fact that the worst perceived consonants will be voiceless consonants. When it comes to the diction, the vocals, which are the most obvious on the acoustic picture, are the best perceived, although the analyzed sound clips are not good for acoustic analysis because of the different conditions which influenced on the quality of the recording as well as on the perception.