The dissertation investigates composite acoustic sound-absorbing panels based on paper sludge (PS), which are the main research object. The goal of the dissertation is to develop an acoustically effective sound-absorbing panel and the sound absorber using paper sludge. This work addresses several tasks: the first three are related to experimental research measurement equipment. It was developed for static air flow resistivity and material sound absorption measurement and used to research and analyse relevant material parameters. The fourth task is related to the theoretical prediction of these parameters and the verification of applicability. The dissertation consists of an introduction, three chapters, general conclusions and references and lists of the author’s publications on the dissertation topic. The introductory chapter discusses the research problem, presents the relevance of the study, describes the research object, formulates the aim and objectives of the work, describes the research methodology, indicates the scientific novelty of the work, its practical significance and the defended statements. The introduction is closed by presenting the author’s publications on the dissertation topic and the structure of the dissertation. The first chapter presents the analysis of the research on paper sludge application and sound propagation. The second chapter introduces the methods of sample preparation and granulometric analysis, determination of static air flow resistivity of paper sludge, determination of acoustic and non-acoustic material parameters, theoretical study of sound absorption as a function of acoustic system parameters and reverberation time modelling. The third chapter describe the research results and the analysis of the acoustic characterisation of the paper sludge composite panels, as well as the development of a sound-absorbing element. Seven scientific articles have been published on the dissertation topic: three in scientific journals included in the Clarivate Analytics Web of Science list, two in peer-reviewed scientific journals referenced in other databases and two in conference proceedings. One patent of the Republic of Lithuania was obtained. Seven conference presentations were made on the dissertation topic at conferences in Lithuania and abroad.