1,721,037 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)
Recording of Italian Opera orchestra and soloists: The musicians point of view
No full textAnechoic recordings of symphony orchestra have been proposed in the literature and have been used in a multitude of studies concerning both innovative measurements and psychoacoustic experiments. Using the same approach, the present work shows the results of a recording campaign focused on the Italian Opera. Different motifs from Italian Operas have been played by professional musicians and soloists in the silent room of the Bologna University. The excerpts have been chosen because of their musical style characteristics and their acoustic properties (dynamics, tymbre, vibrato). The chosen motifs come from scores of Donizetti, Verdi and Puccini, in order to consider various orchestrations and Opera styles.
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
Energy Retrofitting Strategies and Economic Assessments: The Case Study of a Residential Complex Using Utility Bills
Full text linkPromotion of retrofit actions on existing buildings is a goal in Italy, since most of them were built before the 80′s when little attention was paid to energy saving. This paper presents an integrated passive design approach to reduce the heating demand and limit the costs of a representative existing residential complex located in Bologna, in the northern part of Italy. To this purpose, we explored different scenarios upon actions taken on the building structure: (1) High efficiency windows; (2) additional insulation on the external walls; or (3) the simultaneous application of high efficiency windows and improved thermal envelope, on both external walls and roofing. The numerical optimization has been performed dynamically using TRNSYS simulation tool, to evaluate energy consumptions in different structural conditions. Then, the developed model has been calibrated by the real consumption data deduced from energy bills (years 2009–2015). Finally, the energy results obtained in the above mentioned different scenarios have been evaluated under an economic assessment of cost investment: It has been highlighted that the payback time (PBT) results to be strongly influenced by the national policies of fiscal incentives. According to the present model, the most profitable condition is obtained when additional insulation on the external walls is applied: The total amount of energy saving resulted to be equal to 930.4 MWh, with an optimal PBT of roughly six years, when tax refund was contemplated
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
Notes about the early to late transition in Italian theatres
No full textIn some classical room acoustic criteria (e.g. C80, LG, IACC0,x, LF, JLF, JLFC) it is a standard
practice to use a fixed temporal interval to quantify the weight of the early reflections
versus the late reverberation. A value of 80 ms has been proposed in the literature also
for opera houses. This paper, using the same approach of the previous literature, studies the
temporal limit of integration in several Italian historical theatres. Early-to-late energy
ratio and interaural cross correlation are tested and a new integration limit is proposed
The acoustics of the Bayreuth Festspielhaus
No full textThe role of the Bayreuth Festspielhaus in the development of the modern opera house is well known. In spite of the prestige of the Festspielhaus, the values of its room acoustics criteria have been analyzed and reported in few works. A measurement campaign has been recently made in the theatre, placing directional and omnidirectional sources on the stage and in the orchestra pit. Monaural and binaural impulse responses have been recorded on a dense mesh of receivers. Normal factors have been extracted and subjective scale values have been estimated taking into account the peculiarity of the Wagnerian opera
Acoustic measurements in eleven Italian opera houses: correlations between room criteria and considerations on the local evolution of a typology
Full text linkSeveral studies focused on the acoustical characterisation of concert halls and opera houses analysing more or less homogeneous sets of halls and spotting reference criteria.
This work presents the results of a detailed measurement campaign that was carried out over eleven small and mid-sized historical opera houses in the North of Italy with the aim of characterising this hall typology and to relate it to the reference literature. The cluster is intended to represent an adequate sample of case studies relative to different capacities and different design approaches that followed one another starting from the seventeenth century. The theatres were investigated using monaural and binaural techniques, performing impulse response measurements at each seat in the stalls and in each box. Seven ISO 3382 criteria are chosen to characterise these theatres and averaged over the three main listening areas denoted by the Italian opera house typology, i.e. the stalls, the boxes and the gallery. The correlation coefficients between interrelated criteria are presented and commented in relation to the architectural features of the theatres and to the existing literature
Acoustic comfort in primary- and nursery-school canteens: From measurements to recommendations
Full text linkCanteens usually have critical acoustic conditions resulting from the need to maximize the number of occupants while minimizing volume. Thus, in the absence of specific sound absorbing treatments, very high sound pressure levels are usually observed resulting in significant impairment of communication (with increased vocal effort of speakers and reduced speech intelligibility), and dangerously high exposure levels for workers. The present paper reports acoustic measurements carried out in a nursery school canteen having a volume of 212 m(3) and seating about 50 children, and two primary school canteens having volumes of 656 m(3) (seating 150 children) and 367 m(3) (seating 107 children). Reverberation time was measured in each room as well as sound pressure levels during peak occupation (averaged over 15-minute intervals), resulting in A-weighted sound pressure levels spanning between 81 dB (in the nursery school) and 90 dB in the primary schools. Starting from the observed values, considerations about the group-size of the occupants as a function of age were made, and recommendations were finally given to guide the acoustic correction of similar spaces
- …
