Throughout history, many buildings of significant cultural value have been lost due to natural disasters (e.g., earthquakes, volcanic eruptions, subsidence, etc.) as well as other human causes (e.g., fire, war destruction, etc.). The Tajo Opera theatre was hit by an earthquake that led to the collapse of the entire structure eight months after it was built. This paper deals with the revival of the acoustic characteristics of one of the masterpieces of the architect Giovanni Carlo Sicinio Galli Bibiena. The realization of a three-dimensional (3D) model that faithfully reproduces the architectural features of the Royal Tajo Opera theatre of Lisbon allows the authors to perform acoustic simulations that reveal the sound field representing the environment perceived by the audience during artistic performances in Lisbon in 1755. In addition, the simulated results have been compared with the values of the Teatro Comunale of Bologna, which has a similar bell-shaped plan layout and has already been studied by the authors. For the comparison of the two opera theatres, both the stalls and the balconies have been considered.

Many acoustic studies have been conducted in the San Carlo Theatre of Naples over the centuries. The discovery of valuable acoustic measurements from 1998 led the authors to photograph the architectural and acoustic conditions of the Theatre prior to restoration works in 2008. As the first opera house built in Europe, the San Carlo Theatre has always offered a rich artistic programme, making this historic building synonymous with classical music in Naples. From the great variety of operas, three specific sceneries have been selected to analyse the acoustic response based on different geometries and materials located on stage. Acoustic simulations have been performed based on site measurements, starting from a digital model that reproduces the geometry and absorbing coefficients of the materials existing in the Theatre. Using the recorded impulse response, the monoaural and binaural acoustic parameters have been obtained from the acoustic simulations and thereafter compared among the Elektra, Traviata, and La clemenza di Tito sceneries. The results in terms of reverberation highlight that La clemenza di Tito absorbs the high frequencies better than the other two sceneries. Under a clarity perspective, all the sceneries have values above the optimal range limit set for opera houses, although it is typical of other opera theatres built in the same period. A detailed historical background on the architectural changes of the San Carlo Theatre over the centuries is also given to understand the digital reconstruction that modelled the acoustic behaviour of this prominent cultural heritage building.

This paper compares two acoustical projects, applied to the S. Dominic church of Foligno and Imola, which are subject to a permanent and temporary conversion respectively, to places dedicated for listening to live music. Sets of measurements have been undertaken before the acoustical treatments in order to calibrate the digital model; in Foligno, the measurements have also been performed after the installation of the acoustical features, to check if the aims have been achieved. Between the proposed acoustical projects, only one has been realized in Foligno, with the artistic activity still running inside the auditorium. The challenge to adjust the acoustics of reverberant rooms like churches to host musical venues has been achieved with a good quality of sound perception. In particular, in S. Dominic church of Foligno, the goal has been hit after many digital simulations that calibrated the redirection of the sound towards the sitting areas.

The performance of opera and the post-pandemic slow recovery of the public, who have been hesitant to return to frequent attendance of cultural venues, has inspired the authors to analyze the acoustic behavior of the National Theater of Zagreb, by reflecting five specific scenarios. Starting from acoustic measurements undertaken inside the National Theater of Zagreb without any scenery in place, this research study compares the main acoustic parameters simulated with the scenery of Tosca in three different acts. A numerical model was realized by reproducing the geometry and the architectural features of this historic performance arts space. Before the simulations, the absorption coefficients applied to the digital entities were calibrated with the values gathered from the recorded impulse responses. After the calibration process, the acoustic simulations were also carried out with the presence of an audience at two percentages of occupancy.

The acoustic characteristics and spatial features of the world’s only surviving Italianate Gordonia-style miniature theatre, one of the smallest theatres in the world, have inspired the author to analyse the acoustic behaviour of the Monte Castello di Vibio theatre, also called “Teatro della Concordia”. In this paper, the geometric and architectural features of this historical and unique performing art space were first reproduced, considering that these features are essential factors affecting acoustic characteristics. Subsequently, the acoustic measurements were taken throughout the stall and inside some selected boxes, and their main parameters were acoustically characterised according to ISO 3382-1. Lastly, the main acoustic parameters of the Monte Castello di Vibio theatre were compared to those of the 1763 theatre in Bologna, which is also a miniature theatre of similar size. The aim is to explore the main influences on the acoustic parameters of miniature theatres, and the results show that the plan layout of the theatre and interior decoration are the main factors influencing the acoustic characteristics rather than volume. Preserving the acoustic features of this unique heritage building is also seen as one of the goals of this paper.

The Ponchielli theater of Cremona was built in 1808 after a fire destroyed the old wooden structure. The interior, the architecture and the shape of the plan layout are reminiscent of the Teatro alla Scala, Milan, a masterpiece by the architect Piermarini, albeit on a smaller scale. The four orders of balconies crowned by the top gallery are typical features of a 19th Century Italian Opera theater. Acoustic measurements have been undertaken across the stalls and in some selected boxes according to ISO 3382. The main acoustic parameters resulting from the measurements have been used for the acoustic calibration of a 3D model representing the Ponchielli theater. The calibration has been used to compare different scenarios involving the acoustic response of the main hall at 50% and 100% occupancy. The outcomes indicate that no significant change can be detected when the seats are provided with robust upholstery, which can be considered a positive result, especially for the actors who are not forced to change their effort between rehearsal and live performance. In order to contextualize the measured values in relation to the optimal ones, a comparison with other Italian Opera theaters provided with similar architectural characteristics has been carried out. Overall, the findings indicate that the acoustics of the Ponchielli theater are suitable for both music and speech in line with the other selected theaters, as these places were mainly created for multifunctional purposes in the 19th Century.