Dvornyk O. Methods and systems for evaluation and correction of acoustic characteristics of premises for public performances

Dvornyk O.O. Methods and systems for evaluation and correction of acoustic characteristics of premises for public performances. - Qualifying thesis as a manuscript. Dissertation for the Doctor of Philosophy degree in Electronics. - National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", Ministry of Education and Science of Ukraine, Kyiv, 2024. The dissertation is aimed at researching ways to improve the accuracy and speed of evaluating the acoustic characteristics of premises under the influence of noise and reverberation, as well as investigating methods for correcting these characteristics. The content of the dissertation research is presented in four chapters, where the main results of the work are outlined and justified. The relevance of the dissertation is substantiated in the introduction, where the purpose and objectives of the research are formulated, research methods are described, and information is provided on the scientific novelty and practical significance of the obtained results. In the first chapter, a review of existing methods and approaches for assessing speech intelligibility in a room, analyzing early reflections in the room, and methods for correcting room acoustics is conducted. It is shown that in existing scientific works dedicated to studying speech intelligibility, the question of which method of speech intelligibility assessment is optimal, according to the criteria of accuracy and measurement speed, remains insufficiently studied to address the set task, considering the prior information about the adverse conditions. The investigation of early reflection detection methods is relevant because analyzing the moments of appearance of early reflections allows conclusions to be drawn regarding their impact on speech intelligibility and to localize the directions of reflection arrival to the listener. The analysis of existing scientific works has shown that there is no comprehensive answer to this question yet. Another promising direction for research is frequency correction of room acoustics. Although this issue is quite actively researched worldwide, it is currently difficult to find recommendations regarding the choice of correction method in real-time considering the changing occupancy of the room. The second chapter is dedicated to comparing various types of modulation methods for assessing speech intelligibility in terms of measurement accuracy. The comparison results in recommendations for the application of methods depending on the task. The use of a multi-component test signal is proposed for comparing direct and indirect methods of speech transmission index assessment, and a comparison of direct and indirect methods of speech transmission index assessment is also conducted. The third chapter presents methods of acoustic expertise of premises using an artificial head. It is shown that household acoustic equipment can be used to conduct measurements that are not inferior in accuracy to those obtained with professional equipment. It is demonstrated that achieving acceptable measurement accuracy is possible provided that the proposed method of correcting the frequency response of the measurement path is used. The fourth chapter presents the results of instrumental assessment of the quality and correction of the premises. The results of subjective and objective assessments of speech intelligibility, taking into account the influence of noise, early and late reflections, are presented. A hardware and software complex for analyzing sound reflection directions in the premises has been developed, and the effectiveness of the proposed method of correcting the frequency response of the premises in real time using a multichannel compressor has been demonstrated. The new theoretical and practical results presented in the dissertation can be recommended for use in the development and operation of systems designed for acoustic assessment of premises, including speech intelligibility measurement, and frequency correction of premises.