1,720,975 research outputs found
Boundary conditions for hybrid simulations in a rectangular environment with sound-absorbing ceiling
Full text linkAcoustic numerical models facilitate sound field prediction in challenging real-world scenarios, such as environments with non-uniform sound absorption distribution. The accuracy of their results strongly depends on the reliability of boundary conditions required as input data. Research has largely covered analytical models of pressure-based boundary conditions for wave-based simulation techniques. However, accessible lists of frequency-dependent acoustic impedances remain limited compared to the energy-based datasets widely available in the literature. Consequently, random-incidence absorption coefficients are often converted into complex surface impedances through non-unique processes. This work explores the potential discrepancies between the input data of a wave-based finite-element model (hybridized with ray-tracing), and the energy-based coefficients employed in analytical predictions and geometrical acoustics simulations. The 3D model of an existing rectangular space with a highly sound-absorbing surface (the ceiling) is a suitable test environment for this investigation. Room criteria obtained with in-field acoustic measurements, i.e., reverberation time and speech clarity, are the experimental reference data throughout the work. Focusing on the air-backed sound-absorbing tiles at the suspended ceiling, results reveal gaps in input data, suggesting a potential percentage of discrepancies between the analytical formula and numerical models' input data up to 25% at low-mid frequencies (125 Hz - 250 Hz - 500 Hz)
Acoustic comfort in a worship space made of cross-laminated timber
No full textThe construction of a new worship space in cross-laminated timber provides a good opportunity to include acoustic needs in the whole design development. The surface porosity and the lightweight of wooden elements may be carefully considered in order to improve the intelligibility of priests’ voice. In this work, a practical approach for obtaining a global acoustic comfort using sustainable materials is provided, using geometrical acoustic simulations. Material properties and architectural geometries were taken into account in order to evaluate subjective reverberation, speech intelligibility, and spatial perception over the whole audience. Results show how the sound energy distribution in the case study follows the sound field models proposed by scholars and how the ceiling shape—inspired by industrial sheds—contributes to the acoustic comfort of the faithfuls
Assessing human activity noise in workspaces using machine learning and numerical models
No full textAcoustic comfort of workspace environments is deeply dependent on the balance between indoor background noises. For example, colleagues’ speaking might aect task performances by downgrading privacy and productivity. Conversely, HVAC noise can reduce the employee’s distraction since such continuous mechanical noise is detrimental to speech comprehension. Therefore, in the analysis of workspaces’ acoustic comfort, dierent background noise sources identification becomes essential. In this regard, machine learning techniques are resourceful for clustering sound pressure level patterns among the unlabeled data. A previous work by the authors provided reliable results on separating noise sources via Gaussian Mixture Model and K-means clustering. Nevertheless, such method was applied to a single workspace, and thus it needs further investigation on a wider sample of environments. For this reason, in the present work long-term monitoring was carried out in various active workspaces extending previous results and confirming the procedure’s robustness. Moreover, simulations of the acoustic conditions by summing up the human activity contribution to the mechanical noise allowed obtaining more reliable speech intelligibility criteria at the workstations. Refining the numerical models’ setup through background noise levels obtained through machine learning analysis enhances the assessment of workers’ privacy conditions in realistic scenarios
Acoustic analysis of a well-preserved Renaissance music space: The Odeo Cornaro in Padua
Full text linkThe Odeo Cornaro is a remarkable example of Renaissance architecture featuring an octagonal umbrella-vaulted hall surrounded by four adjacent barrel-vaulted spaces. According to the principles outlined by Vitruvius, the central octagonal hall was prized for its acoustical qualities, emphasizing sound propagation and vocal resonance. Due to its remarkably well-preserved condition, the structure continues to serve as a prestigious venue for musical and cultural events. This study investigates the acoustic of this remarkably preserved musical space, employing measurements and numerical models. Finite element analysis and geometrical acoustics models were employed to gain comprehensive insights into sound pressure level distribution across a broad frequency spectrum. The Odeo stands as an outstanding historical music venue due to its capacity to enhance vocal projection while maintaining an intimate ambience during musical performances
Influence of thermal deformations on sound absorption of three-dimensional printed metamaterials
No full textAcoustic metamaterials (AMMs) are designed with complex geometrical shapes to obtain unconventional sound-absorbing performances. As additive manufacturing is particularly suited to print complex structures in a more straightforward and controllable way, AMMs often exploit three-dimensional (3-D) printing techniques. However, when exposed to different temperature conditions, such structures can be affected by geometrical deformations, especially when they are polymer-based. This can cause a mismatch between the experimental data and the expected theoretical performance; therefore, it is important to take thermal effects into account. The present paper investigates the influence of thermal deformations on the sound absorption of three geometries: a coplanar spiral tube, a system with double coiled resonators, and a neck-embedded resonator. Measurements were performed on each 3-D printed specimen in the impedance tube after the samples had been placed in a climate chamber to modify the temperature settings (T = 10-50 & DEG;C). Numerical models, validated on the measurements, were employed to quantify the geometrical deformation of AMM structures through a multiphysics approach, highlighting the effects of thermal stress on the acoustic behavior. The main outcomes prove that the frequency shifts of sound absorption peaks depend on temperature configurations and follow exponential regressions, in accordance with previous literature on polymeric materials. (C) 2022 Acoustical Society of America
Acoustic design of a multipurpose hall inside a former church
Full text linkThe present work is about an acoustic design for a former church converted into a multi-purpose auditorium. The current status of the hall has been classified by means of an acoustic measurements campaign complying with technical standards requirements. A numerical model, which has been calibrated through the measured values, led to the development of the acoustic design that includes sustainable and not-invasive interventions. In contrast with the practical habits, which would use a large amount of sound absorbing materials, an array of suspended reflecting panels over the musicians positions has been introduced. Exploiting the reflecting and scattering properties of those objects, sound clarity and speech definition improve. All the treatments are validated using numerical simulation softwares in order to estimate the efficiency of the whole improvement proposal
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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