Analysis of the Acoustic Parameters of the Maria Zankovetska Theatre in the Lviv before and after Modernisation of the Audience

Abstract

The building of the Maria Zankovetska Theatre in Lviv was founded in 1837-1842. In the years 1941-1944, as a result of damage to the building structure, the building was partially reconstructed. In place of four balconies with boxes, two balconies with amphitheatre arrangements of the audience were built. Currently, the audience has 799 seats, including 531 on the ground floor and 268 on two balconies. Renovation work carried out in 2017 included the replacement of worn-out armchairs and the renovation of the floor. Previous chairs were covered with thick upholstery made of seagrass and velour. Newly mounted seats also have thick layers of upholstery made of PU foam covered with velour. The aim of the research was to analyse the acoustic parameters of the theatre's historic interior before and after changing the armchairs. The article presents the results of acoustic parameters measurement of the hall without spectators before and after modernisation. The measured parameters were used to calibrate the numerical model of the hall. Next, the acoustic analysis was carried out. The reverberation time T20 and the speech transmission index STI were calculated and used to assess the hall acoustics with spectators. A comparison of the results showed that after installing new seats in the theatre the reverberation time values for medium and high frequencies decreased, while for low frequencies they increased. In turn, after replacing the seats, the STI values increased. The obtained results showed that the most important impact on the acoustic parameters of the theatre is provided by upholstered armchairs with high sound absorption, which is related to their construction, thickness of the upholstery as well as their quantity and arrangement in the room.