Dariah.lab is a research infrastructure created for digital humanities, consisting of state-of-the-art hardware and dedicated software tools. One of the tools developed for digital musicology is Timbra, a web-based application for conducting research on sound timbre. The aim was to create an easy-touse online tool for non-programmers. The tool can be used to calculate, visualise, and compare different timbre characteristics of uploaded audio files and to export the extracted parameters in CSV format for further processing, e.g. by classification tools. The application offers extraction and visualisation of scalar features such as zero crossing rate, fundamental frequency, spectral centroid, spectral roll-off, spectral flatness, band energy ratio, as well as feature vectors (e.g. chromagram, spectral contrast, spectrogram, and MFCCs). An interested user can compare selected sound characteristics using various types of plots and run dissimilarity analysis of timbre parameters by means of 2D or 3D multidimensional scaling (MDS). The paper showcases potential applications of the tool based on presented case studies. In terms of implementation, the calculations are performed at the backend Django server using Librosa and standard Python libraries. Dash library is used for the frontend. By offering an easy-to-use tool accessible anytime and anywhere through the Internet, we want to facilitate timbre analysis for a broader group of researchers, e.g. sound engineers, luthiers, phoneticians, or musicologists.

The paper deals with the problem of acoustic correction in historic opera theatres with the auditorium layout in the form of a horseshoe with deep underbalcony cavities limited with a semicircular wall surface. Both geometry of the cavities and excessive sound absorption determine acoustic phenomena registered in this area of the hall. The problem has been observed in the Theatre of Opera and Ballet in Lviv, Ukraine, where acoustic tests were carried out, simulation calculations performed, and finally a diffusion panel worked out designed for the rear wall of the underbalcony space. Acoustic measurements carried out after installation of the diffusers revealed favourable changes in the sound strength factor G within the range of medium and high frequencies in the underbalcony and auditorium centre area. By replacing textile tapestry with diffusion panels, a significant reduction of sound absorption was achieved for the frequency range above 1 kHz and an increase of uniformity of acoustic parameters registered in the hall. The method presented in the paper can be applied in historic halls of the similar type as well as contemporary rooms where there is a need for correction of acoustic flaws related to sound focusing or the echo effect.