1,720,976 research outputs found
The sound of a monumental architecture
Full text linkThe present work is intended to be a scientific commentary on the “SynAsTex Korrektur” sound performance by the German artist Florian Hecker. The choice of the venue for the performance fell on the rationalist atrium of the School of Engineering of the University of Bologna, which is part of a historical building dating back to the 1930s. The study tries to answer some questions. Which role can be played by the acoustics of a monumental atrium-which is made by marble and reflective surfaces-in an electronic performance? How much may the presence of the standing audience influence the room acoustics? Which are the peculiarities of the sound energy distribution in this kind of strongly non-diffuse sound field? The assessment of the acoustic condition was carried out through acoustic simulations, employing a ray-based approach.Le présent ouvrage se veut un commentaire scientifique sur la performance sonore “SynAsTex Korrektur” de l'artiste
allemand Florian Hecker. Le choix du lieu de la représentation est tombé sur l'atrium rationaliste de l'École des Ingénieurs de
l'Université de Bologne, qui fait partie d'un bâtiment historique datant des années 1930. L'étude tente de répondre à certaines
questions. Quel rôle peut-elle jouer l'acoustique d'un atrium monumental - constitué de marbre et de surfaces réfléchissantes -
dans une performance électronique? Dans quelle mesure la présence du public debout peut-elle influencer l'acoustique de la
salle? Quelles sont les particularités de la répartition de l'énergie sonore dans ce type de champ sonore fortement non diffus?
L'évaluation de l'état acoustique a été réalisée par des simulations acoustiques, en utilisant une approche basée sur les rayons
sonores
Enhancing the strength of symphonic orchestra in an opera house
Full text linkNowadays, historical opera houses are also employed for symphonic music, especially in a country like Italy where they are far more widespread than concert halls. The aim of the work presented here is to modify the acoustic conditions of an opera house by introducing an overhead reflector array and removing drapes from the stage, so to meet the requirements for an orchestral performance. The design process and the shape optimisation of the canopy layout were developed with a Geometrical Acoustic (GA++) model. In-situ acoustic measurements were used to calibrate the model, to adjust the tilt angles of the panels and to validate the software–aided design. Combining theoretical studies with practical needs, the results of this work give the opportunity to investigate the consequences of placing a reflector array in an opera house. A multi-decay analysis on measured impulse responses shows that the reflector array enhances the acoustic coupling between the stage house and the main hall. Finally, the blending effect on the orchestral sections caused by the reflector array was estimated through a simulation employing calibrated virtual instruments
Rediscovering the Acoustics of a XII-Century Rotunda through FDTD Simulation
No full textRotundas are circular domed architectures widespread in Western and Eastern territories of the Roman Empire since the time of the early Christianity. While Latin-cross churches were employed to host public masses, centrally planned buildings were often utilized for Baptismal rituals or by monks for private praying and chanting. This latter particular use of rotundas is closely related to the acoustic peculiarities of the architectures, that provide intimacy and, at the same time, enough reverberance for vocal support. The present paper is focused on a XII-Century rotunda located in Bologna (Italy), still preserved. The worship space was incorporated within a XIX-Century villa and it was recently rediscovered after restoration. The 3-D virtual model was obtained through laser scanning techniques and then properly simplified to be adapted to acoustic requirements. A finite-difference time-domain (FDTD) model using frequency-dependent impedance boundary conditions was calibrated based on acoustic measurements. The possibility of wave-based algorithms to naturally compute edge diffraction and wave interference allows employing of the FDTD code as a research tool for the analysis of the diffraction from the niches in the sidewalls, or other acoustic effects due to this curved and domed space of the past
Assessment of modal density and free path distribution in central-planned halls
Full text linkCentral-planned halls are highly widespread in the historical architectures of the Western world, such as rotundae, Christian baptisteries, and Roman tombs. In such halls, whispering galleries, flutter echoes, and sound focusing are the acoustic phenomena mainly investigated by scholars. Instead, modal behaviour and free path distribution are generally less treated in literature. The present study explores the modal density at low frequencies and the relationship with the most recurrent free path lengths in three historical nearly circular spaces, here assessed as case studies. Acoustic measurements allowed the collection of objective experimental data, i.e., room impulse responses and the resulting room acoustics criteria. Wave-based numerical models allowed for the investigation of the eigenfrequencies distribution, while the free paths trend has been experienced through ray-based models. The main outcomes of both analyses show the prominence of the circular modes, rather than the diametral and the elevation ones. Moreover, the mean free path calculated using ray-tracing proves to be higher than the theoretical value commonly assumed for any kind of shape. The consequent longer reverberations compared to halls with other shapes and the same volume justify the significant support historically provided to sound signals by circular halls
Acoustic performance of multi-resonator screens in a virtually reconstructed open-plan office
Full text linkSound-absorbing barriers and screens are commonly employed to mitigate one of the most annoying noises in workplaces: intelligible speech. However, isolating their acoustic contribution from all the other elements (ceilings, wall treatment, or carpets) is challenging. This study uses a wave-based room acoustic modeling approach to explore the acoustic function of desk screens in a virtually reconstructed open-plan office. Analytical models, finite-element simulations, and experimental data from 3D-printed samples allowed defining a multi- resonator unit cell, attenuating the voice signal's main formants. The sound-absorbing panels composed of the unit modules iteration are assessed in the full-scale digital model, starting from the calibrated version on infield measurements. The wave-based engine employed in this study grants the crucial aspect of computing the acoustic performance of the potential multi-resonator screens, including the edge diffraction due to their desk installation. In the virtual workplace, the acoustic role of such screens in increasing the speech level decay is outlined in comparison with the calibrated scenario and the traditional screens' option
A virtual orchestra to qualify the acoustics of historical opera houses
Full text linkItalian 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
An attempt to rank Italian historical opera houses based on numerical simulations
Full text linkDue to the complexity of the acoustic field in articulated closed spaces, architectural acoustics is often approached as a reverse-engineering problem: criteria, reference values and analysis methods are extrapolated by comparing results from measurements in a set of case studies. Considering the methods and the results of previous works on Italian historical theatres, the present study shows the results of geometrical acoustic (GA) numerical simulations with the aim to attempt a ranking based on the subjective preference theory. The models were calibrated using several room criteria that had been previously measured in the framework of a measurement campaign performed in Italian theatres. The cluster chosen is intended to represent an adequate sample of case studies relative to different capacities and different design approaches, which were first developed in the seventeenth century
Understanding the acoustics of St. John’s Baptistery in Pisa through a virtual approach
Full text linkThe virtual acoustics provide an important tool in the comprehension of the architectural evolution of a
historical place, offering the possibility to consciously operate for its preservation. St. John’s Baptistery represents an outstanding example of medieval architecture, recognized as UNESCO World Heritage and popular for its huge reverberation. When compared to other similar central-symmetry buildings, the Baptistery proves to be an outlier, enough to raise the interest of scholars. A model of the building was calibrated considering in situ acoustic measurements, the material properties and the liturgical use. The numerical simulations of the current geometry and the early design hypotheses are used to understand the factors affecting the peculiar sound behaviour. The temporal analysis of a Gregorian chant – ad hoc recorded – seems to confirm the needing of large reverberation
UNCERTAINTY OF INPUT DATA FOR WAVE-BASED ROOM ACOUSTIC SIMULATIONS IN LARGE NON-TRIVIAL ENVIRONMENTS
No full textIn the last decades, wave-based simulation methods have been applied to an increasing number of 3D virtual rooms thanks to the scientific and computational advances in numerical models. However, there is still a lack of adequate material properties required for those simulations, in terms of accessible lists of various frequency-dependent boundary conditions. Such input parameters can be retrieved from sound absorption coefficients, exploiting the availability of several consolidated datasets typically employed in ray-tracing simulations. The present work aims at quantifying and assessing the degree of uncertainty underlying this critical step in non-trivial environments. With this purpose, parallel calibrations have been carried out on distinct case studies based on experimental data using finite-difference time-domain (FDTD) and geometrical acoustics (GA) approaches. The outcomes highlight significant discrepancies at low frequencies between the different input data for various materials, suggesting a potential decrease (up to 45%) in sound absorption coefficient before the conversion to specific acoustic impedances
A Virtual Acoustic Restitution of St John’s Baptistery in Pisa
No full textVirtual acoustics is a useful tool for studying ancient environments now part of our cultural heritage. The
acoustic restitution of an existing building, or even of a no more existing building, allows understanding its
acoustic and architectural evolution. St. John’s Baptistery is located in Piazza dei Miracoli (Pisa), which is
a homogenous architectural ensemble including the Leaning Tower and the Cathedral. Due to the succession
of different masters, the Baptistery was built in stylistic disagreement with the earliest design, resulting in the actual architecture that provides interesting acoustic peculiarities. This work presents the virtual acoustic restitution of potential first designs, based on previous studies. The accurate calibration of the existing Baptistery model enables us to achieve a believable acoustic restitutions through the auralisation techniques. More in details the acoustic coupling between the volumes of the building – respectively the dome, the matroneum and the ambulatory – was studied with measurements and numerical simulations. Furthermore, the layout of a Gregorian soloists in the choir part of the Baptistery was simulated according to musicological researchers, both in unoccupied and occupied conditions
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