Advances in diffusive surface design using 3D architectural parametric modeling programs

Diffusive surfaces need to be optimally designed for both acoustic performance and aesthetic values. These aspects are at the heart of the design workflow and should respond to the requirements of both architects and acousticians. Advances in parametric modelling through digital tools have led to the integration of performance investigations and architectural design process. Moreover, parametric modeling software are also useful tools for manufacturing. Indeed, they can reduce the production time as they can easily be integrated inside the manufacturing process. Although, it is more than a decade that the standard ISO 17497:2004 has proposed the scattering and diffusion coefficients measurements, further work is needed in order to increase designers’ awareness on diffusive surface design through simple design rules and approaches. This research goes through three steps. First, it investigates the diffusive surface properties databases in order to extrapolate basic geometric guidelines for diffusive surface optimization. Second, it analyses a series of case-studies that apply the parametric modeling to the design of diffusive surfaces. Finally, it suggests a design process for diffusive surfaces by integrating parametric models and acoustic simulation aiming to provide architects and designers with rapid visual and acoustic feedback at a preliminary stage of their design

Towards a sustainable approach for sound absorption assessment of building materials: Validation of small-scale reverberation room measurement

The research and development phase of sound absorptive building materials by designers, engineers, acoustic consultants and architects need tools for fast, inexpensive preliminary comparison tests on products or acoustic systems. The existing methods exhibit some drawbacks: the impedance tube (IT) is not suitable for 3D systems, while the full-scale reverberation room (FSRR) requires test samples of large dimensions. To overcome these limitations, this work aims to explore the capabilities of small-scale reverberation rooms (SSRR) of about 3 m3 located at Politecnico di Torino in evaluating the randomincidence sound absorption coefficient. In order to define the range of application and reliability of the method, the considered factors are the sample area and its orientation on the room floor. Four different materials have been tested by applying IT, FSRR and SSRR. The absorption coefficients data obtained with SSRR are compatible with the FSRR benchmarking in the 400–5000 Hz frequency range for three porous materials, and in the range 1000–5000 Hz for the thin rigid material. Therefore, the SSRR can be considered as a reliable alternative for the sound absorption characterization in these ranges for this kind of materials, leading to several benefits. Among them, samples with reduced size can be evaluated with a cheaper equipment in a short time, increasing the overall economical sustainability of the measurement process; in turn, this can encourage designers and architects to perform acoustical measurements since the very early research and development phase, leading to an overall reduction of design costs and improved product quality

Long term monitoring of noise pollution in social gatherings places: time analysis and acoustic capacity as supports of management strategies

City of Torino (Italy), as many European cities, is facing noise pollution related to recreational noise of nightlife in open urban areas, such as streets, squares and terraces, where thousands of people meet spending all evening and night time. Noise from people speaking in these spaces can be very loud, due to crowd levels (since communication is possible only with a raised voice level) and people behavior. This study shows the analysis of long term noise data collected in two years by a low-cost IoT network in San Salvario area. It highlighted regularities on night levels, mainly on a weekly basis with a seasonality. Preliminary investigations on time series have been developed, in order to correlate noise levels and number of people involved, coupling environmental noise data and crowd sensors. Moreover, the concept of ‘Acoustic Capacity’ related to the noise levels has been investigated. This approach based on a deeper quantitative knowledge is explored as an help to local administration and stakeholders in planning and implementing mitigation actions

Alternative Spaces for Learning: Reversible Acoustic Treatments for Transformation of Spaces into Classrooms During COVID Era

The design of acoustic comfort in classrooms is a challenging issue. It became a crucial aspect during the Covid-19 pandemic regarding class life organization, as for the latter large spaces for teaching were required in order to guarantee the minimum distance between the occupants to limit the spread of Covid-19, and it was important to ensure their acoustics functionality for the performance of lessons. To this aim, this investigation is to provide a guide (for school principals, administrators, safety managers, architects and engineers, acousticians) where easily implementable solutions for different types of school buildings are detailed in various case studies and they are an example in case of environments similar in shape and volume. In particular the focus is put on the transformation of school spaces created for different purposes than normal classrooms (e.g., corridors, atria, sports halls) into classrooms for teaching. Different layouts of the furniture and sound-absorbing materials have been applied and analysed by simulations (Odeon 15) comparing the results with the standardized optimal values and with those of the actual environments obtained through an extensive measurement campaign. Eight schools were taken into account as case studies, representing the Italian school heritage and including elementary schools, middle schools and high schools. A total of 26 different spaces with a volume varying in the range 135-2800 m3 were analysed. For each of them, both general analyses at the overall environment level and more specific ones for single receivers located over the area occupied by the students were carried out. As a result, it should be highlighted that the proposed solutions could not be fully acoustically optimized for all of the spaces, as the analyses also took into consideration an affordable cost, the speed of realization and the reversibility of the intervention

Applicability of multi-objective optimization in classroom acoustics design using analytical and geometrical acoustic models

The purpose of this study is to improve the acoustic quality of classrooms for a better teaching-learning process by the development of a routine which aids in the optimization of typology, extension and position of acoustic materials. It is a tool addressed to architects, building designers and professionals alike that are involved in the planning, construction and renovation of rooms. One classroom in Turin has been selected for this study and a basic geometric model has been built in Grasshopper, that serves as the environment for parametric investigation and improvement of acoustics parameters. Reverberation time and STI, which are considered as the most important descriptors in classroom acoustics have been determined using theoretical calculations (Sabine, Eyring and Barron&Lee theories) and geometrical acoustic (GA) simulations (Pachyderm). The latter allows to take into account the scattering properties of surfaces and different combinations of all the acoustic materials Finally, Octopus has been used to perform multi‐objective optimization runs considering as objectives the acoustic parameters and the acoustic design/renovation costs. The algorithm has been developed in order to allow to choose different optimization sets depending on the material or the type of acoustic treatment to optimize. Said model provides, essential information on the acoustic quality of the classroom and recommendations on how to increase it by improving teaching-learning activities; which would normally be time-consuming. The results show that the GA simulations and theoretical calculations are compatible for the solutions without scattering properties. However, it needs further development in order to extend its application field in fact right now operating on the Grasshopper canvas would require significant knowledge on the designer?s behalf concerning parametric design and acoustics

INFLUENZA DI DIVERSI MATERIALI DI FACCIATA SULL’ ACUSTICA DI UNO SPAZIO URBANO

Gli spazi pubblici rivestono un ruolo fondamentale all’interno della città e numerosi studi hanno riconosciuto una crescente importanza della percezione multisensoriale di tali spazi da parte degli utenti. In questa pluralità di sensi, l’udito gioca un ruolo fondamentale, dovuto alla sua qualità immersiva. Lo studio dell’ambiente esterno dal punto di vista acustico è ancora tuttavia legato molto spesso alla semplice riduzione del rumore ambientale. Così, l’involucro edilizio è studiato essenzialmente in relazione al fono isolamento degli ambienti interni e l’utilizzo di materiali fonoassorbenti in esterno, come facciate e tetti verdi, è stato indagato finora in relazione alla riduzione dei livelli di rumore da traffico. Tuttavia, il soundscape urbano è un’entità complessa, che riveste un ruolo che va al di là del semplice rumore ambientale, come riconosciuto recentemente anche a livello di normativa internazionale (ISO 12913-1:2014). È perciò necessario indagare come la scelta di diversi materiali di facciata possa influire sull’ambiente acustico esterno, il quale a sua volta influenzerà la percezione dello spazio da parte degli utenti. Il presente studio mira ad essere un primo passo in questa direzione, contribuendo ad aumentare la consapevolezza di architetti e urban planner su come l’involucro edilizio possa avere un’influenza sull’ambiente esterno sotto molteplici aspetti, e quindi a consentirne una progettazione più consapevole e “oggettivamente misurato” nei suoi effetti. Diverse simulazioni acustiche sono state condotte mediante il software ODEON 13.02 utilizzando il modello virtuale di una piazza di piccole dimensioni, precedentemente tarato utilizzando misure in campo. In tale modello, sono state variate le proprietà acustiche dei materiali di facciata degli edifici, ovvero i coefficienti di scattering e di assorbimento, basandosi su una banca dati di possibili materiali utilizzabili in esterno ricavata da letteratura esistente,per indagarne l’influenza sui parametri acustici calcolati in diversi punti della piazza, come tempo di riverberazione e livello di pressione sonora

Listeners Sensitivity to Different Locations of Diffusive Surfaces in Performance Spaces: The Case of a Shoebox Concert Hall

Diffusive surfaces are considered as one of the most challenging aspects to deal with in the acoustic design of concert halls. However, the acoustic effects that these surface locations have on the objective acoustic parameters and on sound perception have not yet been fully understood. Therefore, the effects of these surfaces on the acoustic design parameters have been investigated in a real shoebox concert hall with variable acoustics (Espace de Projection, IRCAM, Paris, France). Acoustic measurements have been carried out in six hall configurations by varying the location of the diffusive surfaces over the front, mid, and rear part of the lateral walls, while the other surfaces have been maintained absorptive or reflective. Moreover, two reference conditions, that is, fully absorptive and reflective boundaries of the hall have been tested. Measurements have been carried out at different positions in the hall, using an artificial head and an array of omnidirectional microphones. Conventional ISO 3382 objective acoustic parameters have been evaluated in all conditions. The results showed that the values of these parameters do not vary significantly with the diffusive surface location. Moreover, a subjective investigation performed by using the ABX method with auralizations at two listening positions revealed that listeners are not sensitive to the diffusive surface location variations even when front-rear asymmetric conditions are compared. However, some of them reported perceived differences relying on reverberance, coloration, and spaciousness

Improved Room Acoustics Quality in Meeting Rooms: Investigation on the Optimal Configurations of Sound-Absorptive and Sound-Diffusive Panels

This work deals with the improvement of the room acoustic quality of two medium sized meeting rooms through the investigation of the optimal placement of absorption and diffusive panels on the walls and ceiling. Acoustic measurements have been carried out in the existing untreated rooms with ODEON 13 room acoustics measurement and prediction software, and the Adobe Audition plugins Aurora. Simulations of different combinations of sound absorption and diffusion treatments have been carried out with the updated version of the software, ODEON 15. The panels were positioned in the meeting rooms following the guidelines of the DIN 18041 standard and the scientific literature. The results advise the application of absorptive materials on the ceiling or around the borders, creating a reflective middle area, and on the upper part of one the lateral walls, including the rear wall. Configurations with diffusers do not generally bring significant improvements. The Speech Transmission Index (STI) is a less sensitive parameter for the different acoustic scenarios, compared to Reverberation Time (T) and Clarity (C50). The research also outlined a design workflow, useful to successfully design meeting rooms and rooms for speech in general, which allows to determine the optimal number and location of acoustic panels and to minimize the costs

S&N-S LIGHT: IL DISPOSITIVO CHE CONTROLLA IL RUMORE ANTROPICO NEGLI AMBIENTI DENSAMENTE OCCUPATI INCORAGGIANDO IL COMPORTAMENTO ADATTIVO DI ABBASSAMENTO DEI LIVELLI DI VOCE

Il raggiungimento del comfort acustico negli ambienti pubblici è basato principalmente sul controllo dei parametri acustici oggettivi, quali il tempo di riverberazione e il livello di rumore di fondo, ai quali talvolta si affiancano indagini soggettive. Queste rivelano una scarsa consapevolezza degli utenti riguardo la qualità acustica, causata verosimilmente della mancanza di informazioni adeguate e dunque di conoscenza del problema. Si nota quindi la necessità di formare l’utente circa la consapevolezza del comfort acustico ottimale e di implementare strategie di controllo attivo che lo vedono direttamente coinvolto, così come sempre più comunemente avviene per il raggiungimento del comfort termico e visivo. Un approccio di questo tipo diventa rilevante per il controllo del rumore prodotto dal chiacchiericcio degli utenti in ambienti densamente occupati, quali scuole, ospedali, luoghi di lavoro e di svago. Il controllo personale della voce, volto a ridurre il rumore antropico all’interno di tali spazi, è dunque un comportamento adattivo auspicabile al fine di evitare effetti negativi in termini di performance, salute e qualità dell’ambiente. Nell’ottica quindi di incoraggiare gli utenti verso il personale controllo della voce, questo studio si occupa di valutare l’efficacia dell’utilizzo di un dispositivo fonometrico intelligente e recentemente brevettato, denominato Speech & Noise Stop-Light (S&N-S Light), che segnala il superamento di livelli sonori limite attraverso un feedback visivo. Quest’ultimo, basato sull’accensione dei colori verde-giallo-rosso, è controllato da un algoritmo che elabora il livello sonoro confrontandolo a livelli statistici limite e escludendo dal calcolo rumori dovuti a eventi istantanei. Tali livelli statistici sono precedentemente definiti sulla base della destinazione d’uso dell’ambiente. I risultati della campagna di monitoraggio, che ha coinvolto le aule di una scuola primaria, dimostrano come il personale controllo della voce determini un abbassamento dei livelli di rumore durante lo svolgimento delle attività scolastiche e quindi il miglioramento della qualità acustica dell’ambiente stesso

The Recycling and Reuse of Natural Materials: Sound Absorbing Box Patterns That Use Waste from Olive Tree Pruning

The agricultural activity of pruning olive trees generates waste which, due to long-standing practices and unawareness of the consequences, are burned on site, thereby producing CO2 emissions in the atmosphere. Therefore, in order to prevent environmental pollution and a waste of resources, the aim of this research investigation was to highlight some alternative uses of the pruning of olive trees waste. This work focuses on recycled and reused by-products as a secondary raw material for the implementation of interior components that can be used for indoor acoustic correction purposes and evaluates their potential as absorbing materials, without overlooking the aesthetic dimension. In this paper, different configurations based on plywood frames with loose olive pruning chips used as a filler, namely, modules and sub-modules, were investigated. Moreover, other technological details, that is, the influence of a Tissue-Non-Tissue (TNT) layer and a spray film coating applied over the external surface of the loose material, were measured. Sound absorption measurements were conducted inside a small-scale reverberation room (SSRR) and the experimental results demonstrated that the samples, for the given thickness, have weighted sound absorption values (alpha(w)) of between 0.15 and 0.35 and single third-octave band values that can reach higher values than 0.50 above 500 Hz. The frequency curves and weighted values of the samples in which the influence of TNT and the spray film coating were tested remained unchanged. This is a design aspect that allows absorbing surfaces to be modeled and integrated with existing walls, while maintaining the acoustic performance and the specific aesthetic features of the loose material