A virtual orchestra to qualify the acoustics of historical opera houses

Abstract

Italian Historical Opera Houses are private or public spaces built around a cavea, with tiers of boxes on the surrounding walls. At the early age – from 16th to 18th century – boxes were private properties of the richest class, typically the financial responsible of the whole building. The stalls hosted the middle class, that gradually increased its social position and for this reason the wooden seats were progressively replaced by chairs. The gallery was reserved to lower classes. Does this social division correspond to a different acoustic comfort? The present work tries to answer this question using subjective preference models provided by scholars. With this aim, the room criteria defined by different authors and in distinct times are lined up with the ISO 3382 standards and analysed depending on the acoustic peculiarities of an Italian Historical Opera House selected as case study. Calibrated impulse responses were handled through the numerical simulations of a whole orchestra of virtual sound sources in the pit.

Reviving the Low-Frequency Response of a Rupestrian Church by Means of FDTD Simulation

“…FDTD acoustic modelling has been applied to solve acoustic problems for a long time [27] but given the computational load it has been mostly applied to low frequencies [28], while the availability of parallel computation distributed by several GPUs fostered a gradual extension to a much wider frequency range [21,22,[28][29][30]. FDTD starts from the assumption that a generic derivation operator can be replaced by one of its finite difference forms:…”

“…As the finishing was relatively the same over all the surfaces, with the notable exception of the floor covered by hardened soil, and given the values measured for similar materials (Table 2), an initial value of 0.015 was used for the absorption coefficient (obtained by averaging among the 63 Hz and the 125 Hz values). As this value returned slightly longer T30 values than expected, while in acoustic modelling [22] a maximum difference of 5% (corresponding to one just noticeable difference [25]), is considered to be acceptable, step-by-step increases were applied until a value of 0.025 was reached. Under these conditions, the spatial average of T30 in one-third octave bands from 63 Hz to 80 Hz differed by only 2% from measurements, while at 100 Hz the error was 4%.…”

“…To this purpose, in this paper an application of the finite-difference-time-domain (FDTD) method is proposed, by implementing a simple scheme with frequency-independent boundary conditions limited to the lowest frequencies. Even though this method has been already applied to larger buildings and covering a much broader spectrum [21,22] using parallel computation on several graphical processing units, the present implementation aims at providing a useful low-frequency complement to conventional geometrical acoustic-based simulations, without requiring a high computational load.…”

Italian-Style Opera Houses: A Historical Review

“…As a paradigmatic example, the Galli-Bibiena family of architects moved from Italy to European Courts, working as scenic artists and opera-house architects [17]. They designed around the Europe: Grosse Hoftheater, Wien (1708); Great Theatre at Nancy (1709); Teatro Filarmonico, Verona (1719, burned in 1749); Teatro Alibert, Rome (1720); Mannheim Opernhaus (1719, burned in 1795); Royal Theatre, Mantua (1731, burned in 1781); Markgräfliches Opernhaus, Bayreuth (1748) [18]; Dresden opera (1750, burned in 1849); Ópera do Tejo, Lisbon (1752, ruined in 1755); Teatro Rossini, Lugo (1760) [19,20]; Teatro Comunale, Bologna (1763) [21][22][23]; Teatro de Quattro Cavalieri, Pavia (now Fraschini, 1773) [24,25]; Scientific theatre, Mantua (1775, now Bibiena), and many others [26].…”

“…This was the reason why some authors compared the Wagnerian opera-and the Festspielhaus-to the birth of Cinema: the soloist is the actor, the orchestra is the background [192]. During the 20th Century, orchestra pits were progressively introduced in Italian theatres [23,91]. It should be remarked that orchestra pits require further adjustments, to increase the communication to hall and stage [76,193], and to ensure safe working conditions to musicians [194,195].…”