An investigation of multi-rate sound decay under strongly non-diffuse conditions: The crypt of the Cathedral of Cadiz

Martellotta, Francesco; Álvarez-Morales, Lidia; Girón, Sara; Zamarreño, Teófilo

doi:10.1016/j.jsv.2018.02.011

Cited by 19 publications

(17 citation statements)

References 31 publications

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“…The measurements were carried out within two research projects, each of which lasted for 3 years, financed by the National Plan, in order to meet the objectives that were set out in the project, in which the recovery of the intangible heritage was proposed, as was the addition of possible solutions for the improvement of the acoustic behaviour of the cathedrals. The results of these research projects are published in several studies [7][8][9][10]. The RIR reflects the behaviour of a space between the point of emission and that of reception and can be used to calculate the acoustic parameters.…”

Section: Onsite Measurementsmentioning

confidence: 99%

The Acoustics of the Choir in Spanish Cathedrals

2018

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One of the most significant enclosures in worship spaces is that of the choir. Generally, from a historical point of view, the choir is a semi-enclosed and privileged area reserved for the clergy, whose position and configuration gives it a private character. Regarding the generation and transformation of ecclesial interior spaces, the choir commands a role of the first magnitude. Its shape and location produce, on occasions, major modifications that significantly affect the acoustics of these indoor spaces. In the case of Spanish cathedrals, whose design responds to the so-called “Spanish type”, the central position of the choir, enclosed by high stonework walls on three of its sides and with numerous wooden stalls inside, breaks up the space in the main nave, thereby generating other new spaces, such as the trascoro. The aim of this work was to analyse the acoustic evolution of the choir as one of the main elements that configure the sound space of Spanish cathedrals. By means of in situ measurements and simulation models, the main acoustic parameters were evaluated, both in their current state and in their original configurations that have since disappeared. This analysis enabled the various acoustic conditions existing between the choir itself and the area of the faithful to be verified, and the significant improvement of the acoustic quality in the choir space to become apparent. The effect on the acoustic parameters is highly significant, with slight differences in the choir, where the values are appropriate for Gregorian chants, and suitable intelligibility of sung text. High values are also obtained in the area of the faithful, which lacked specific acoustic requirements at the time of construction.

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Section: Onsite Measurementsmentioning

confidence: 99%

The Acoustics of the Choir in Spanish Cathedrals

2018

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“…A close-up of the EDCs shown in Figure 11 shows in greater detail how the stepped decay is overlaid on the broad ripples. This stepped decay behavior has been identified in rooms with strong flutter echo [41], and indicates that there are non-diffuse features of this sound field that need to be evaluated through direct observation of the waveform, rather than simply through the use of traditional room acoustic objective metrics which assume a diffuse field. To this end, a multi-resolution wavelet analysis will be used in the following section for further comparison of flutter echoes in measurements and computer simulation results.…”

Section: Energy Decay Curvesmentioning

confidence: 90%

“…Room acoustic computer modeling studies have primarily made use of available geometrical acoustics softwares [38], and relatively few have made use of wave-based methods in low-frequencies [28,29,33,36], mainly due to the aforementioned computational costs. Models of flutter echoes has been of interest for some time [39][40][41] and spaces with flutter echoes have been previously analyzed with ray models [42].This study aims to make use of GA and wave-based acoustic computer modeling in the study of acoustics of the sanctuary of Christ the King (CTK) Charismatic Episcopal Church of New Paltz, NY. Built in 2009, this church has a barrel-vaulted ceiling over the nave portion of the sanctuary, with the floor of the nave carpeted and covered with rows of upholstered chairs, except for a marble-tiled center aisle along the length of the room.…”

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Computer Modeling of Barrel-Vaulted Sanctuary Exhibiting Flutter Echo with Comparison to Measurements

Lai

Hamilton

2020

Acoustics

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Computer modeling in acoustics allows for the prediction of acoustical defects and the evaluation of potential remediations. In this article, computer modeling is applied to the case of a barrel-vaulted sanctuary whose architectural design and construction led to severe flutter echoes along the main aisle, which was later mitigated through acoustical remediations. State-of-the-art geometrical acoustics and wave-based simulations are carried out to analyze the acoustics of this space, with a particular focus on the flutter echoes along the main aisle, before and after remediations. Multi-resolution wavelet and spectrogram analyses are carried out to isolate and characterize flutter echoes within measurements and computer-simulated room impulse responses. Comparisons of simulated responses to measurements are also made in terms of decay times and curves. Simulated room impulse responses from both geometrical acoustics and wave-based methods show evidence of flutter echoes matching measurements, to varying degrees. Time-frequency analyses isolating flutter echoes demonstrate better matches to measurements from wave-based simulated responses, at the cost of longer simulation times than geometrical acoustics simulations. This case study highlights the importance of computer modeling of acoustics in early design phases of architectural planning of worship spaces.Acoustics 2020, 2 88 can scale even more severely (e.g., to the fourth power of the frequency). As a consequence of these high compute requirements wave-based methods have seen less use over the years than geometrical approaches. On the other hand, wave-based methods tend to be highly parallelizable, and recent progress in parallel implementations [15][16][17][18][19][20], combined with steady increases in compute power from parallel hardware such as graphics processing units (GPUs), are bringing large-scale wave-based simulations to within reach of consumer hardware [21].There are a variety of acoustical spaces that have been investigated in the literature using computer modeling, including worship spaces [22][23][24][25][26][27][28][29], performance spaces [30][31][32], multi-purpose spaces [33,34], and outdoor ancient theaters [35][36][37]. Room acoustic computer modeling studies have primarily made use of available geometrical acoustics softwares [38], and relatively few have made use of wave-based methods in low-frequencies [28,29,33,36], mainly due to the aforementioned computational costs. Models of flutter echoes has been of interest for some time [39][40][41] and spaces with flutter echoes have been previously analyzed with ray models [42].This study aims to make use of GA and wave-based acoustic computer modeling in the study of acoustics of the sanctuary of Christ the King (CTK) Charismatic Episcopal Church of New Paltz, NY. Built in 2009, this church has a barrel-vaulted ceiling over the nave portion of the sanctuary, with the floor of the nave carpeted and covered with rows of upholstered chairs, except for a marble-tiled center aisle along the len...

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“…A singular example of such odd behavior which was investigated by the author and colleagues is the crypt of the Cathedral of Cadiz [26], where the reverberation time measured in the "rotunda" dramatically changed by simply moving the source along the axis. Without going too deeply into the details of the complex phenomena occurring in this space, the problem could be summarized by stating that the shape of the space clearly contributed to originating flutter echoes between the floor and the dome, which became more evident when the source position moved off the border.…”

Section: Reverberation Time Related Issuesmentioning

confidence: 99%

Do we still need diffuse field theory?

Martellotta

2018

The Journal of the Acoustical Society of America

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Plus de vingt ans après l'article de Murray Hodgson intitulé "When is diffuse field theory applicable?", nous avons rassemblé de plus en plus de preuves selon lesquelles la théorie des champs diffus est essentiellement une chimère. Si nous considérons les deux implications les plus importantes du modèle de champ diffus, à savoir la distribution uniforme du niveau de pression acoustique et l'invariance du temps de réverbération, il est assez facile de dire que de telles conditions ne sont pratiquement jamais retrouvées, sur la base de mesures réelles dans plusieurs espaces différents. La diffusion sonore idéale nécessite des conditions ergodiques et de mixage, qui ne se produisent pas nécessairement, notamment lorsque l'absorption acoustique est répartie de manière inégale ou lorsque les pièces ne sont pas proportionnées. Ainsi, apparemment, la théorie des champs diffus pourrait être écartée au profit d'approches plus précises capables de prendre en compte la nature spécifique de chaque espace. De nos jours, nous disposons de plusieurs instruments allant des nombreuses variations de l'algorithme de lancer de rayons à la solution numérique de l'équation d'onde. Cependant, ces méthodes reposent sur la mesure ou l'estimation d'autres coefficients qui, s'ils ne sont pas correctement calculés, peuvent introduire des inexactitudes encore plus grandes. Une analyse critique est présentée ici, principalement basée sur l'expérience de recherche de l'auteur, montrant que la théorie des champs diffus représente toujours un moyen important de comprendre la propagation du son dans des espaces clos.

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An investigation of multi-rate sound decay under strongly non-diffuse conditions: The crypt of the Cathedral of Cadiz

Cited by 19 publications

References 31 publications

The Acoustics of the Choir in Spanish Cathedrals

The Acoustics of the Choir in Spanish Cathedrals

Computer Modeling of Barrel-Vaulted Sanctuary Exhibiting Flutter Echo with Comparison to Measurements

Do we still need diffuse field theory?

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