Courtyards are widely used as semi-open spaces that can support restoration and regulate microclimates in densified urban environments. However, urban soundscape research has focussed on urban open spaces. Following PRISMA guidelines, this systematic review synthesises evidence from 90 studies (retrieved from Scopus up to June 2025) to map the methodological trends, thematic focus, and interdisciplinary intersections of the field. The analysis reveals a gradual shift towards the soundscape approach. (1) Despite acoustic characterisation predominantly relying on sound level parameters (90%, e.g. LAeq), their predictive power for acoustic comfort remains inconsistent within relatively low SPL ranges (IQR = 49.2–59.1 dBA). (2) An increasing number of studies incorporate affective quality attributes (44%) for soundscape assessment. The synthesis (94% of cases) indicates significant associations between acoustic environments and perceptual attributes, though it highlights a context-specific model for the urban courtyard soundscape. (3) While path/infrastructure interventions (92%, e.g. spatial planning) demonstrate quantifiable impact on acoustic mitigation (median attenuation = 2.5 dBA), integrating sound sources with these strategies can enhance overall soundscape quality. (4) In parallel, emerging studies prioritise multi-domain interactions, particularly with thermal environments. Current synthesis reveals complementary cross-sensory effects, in which specific natural sounds can moderate thermal perception. (5) By integrating the climate adaptation framework, the courtyard soundscape can contribute to urban well-being. While spatial factors (e.g. openness) demonstrate comparable impacts on acoustic and other environmental exposures, background sound level (LA90) is specifically associated with restorativeness. Advancing this potential requires developing a multi-domain, resource-efficient approach to soundscape design.
This paper presents a significant contribution through a scoping review of noise sources, their effects on human health, and methods for reducing noise in hospital environments. The review focuses on studies published between 2016 and 2024 that address noise sources in hospitals, their impact on patients and healthcare personnel, and strategies for noise reduction. The analysis was conducted using the MAXQDA commercial software (version 22.4.1) and utilized 454 codes. The findings revealed that conversations among healthcare staff, equipment noise, and clinical activities are the most prevalent sources of noise in hospitals. These are followed by noises from patients, alarms, and visitors. This ranking can help hospital managers prioritize resources when formulating noise reduction strategies. According to the reviewed articles, noise is closely linked to issues such as distraction, increased heart rate (tachycardia), sleep disorders, and reduced employee efficiency. The most frequently recommended approaches for managing noise include personnel training and raising awareness among staff. The results of this study emphasize that hospital noise reduction strategies should be comprehensive, incorporating both technical solutions—such as acoustic treatments and equipment noise reduction—and behavioral solutions, which include staff training and noise condition assessments.
Although people spend most of their night-time hours indoors, environmental noise exposure is typically assessed using outdoor levels. This study examined outdoor-to-indoor noise attenuation across 49 dwellings in Greater London using synchronized and unsupervised measurements, while noise levels were expressed via the A-weighted equivalent (), maximum (), and percentile (, , ) noise indicators. Moderate-to-strong correlations between night-time outdoor levels and outdoor-to-indoor attenuation levels (-) informed the development of multiple and mixed-effect linear regression models to estimate indoor noise levels based on outdoor levels. Mixed-effect models outperformed multiple linear models (RMSE: 0.7-4.9 vs 2.3-5.7 dB(A)), with outdoor levels accounting for most variability, and with additional contributions from the occupation status, window size, and room volume predictors. The estimated attenuation levels ranged from 20 to 26 dB(A), with in line with the WHO recommended 25 dB(A) level. The proposed modeling approach enables estimates of indoor noise exposure, offering a more representative basis for night-time exposure-response assessments in the UK and similar urban settings.
Generator installations are important sources of environmental noise in and around buildings, often exceeding acceptable levels for residential and occupational settings. This systematic review and meta-analysis synthesized quantitative evidence on noise-control strategies for generator systems. Searches of 11 scientific databases to December 2024 identified experimental and field studies reporting measurable noise-reduction outcomes. Twenty-four studies met the inclusion criteria and were pooled using random-effects models. Across all methods—including structural modifications, multilayer acoustic enclosures, silencers, passive materials, vibration isolation, and active or hybrid active–passive noise control—the overall mean reduction was 14.66 dB (95% CI: 12.49–16.83 dB), with substantial heterogeneity. Subgroup analyses indicated superior performance for high-efficiency silencers and well-designed enclosures compared with simple barriers or single-layer treatments. These findings provide consolidated evidence to inform the design and optimization of generator noise-control solutions within the built environment.
This study presents a detailed investigation of the acoustic performance of roller shutter boxes in the extended position, comprising porous and heavy mass layers. Such configurations are of particular relevance, as roller shutter boxes often represent weak points in the façade sound insulation of residential and office buildings. The Finite Transfer Matrix Method (FTMM) is first employed to model the system, providing a robust description of its acoustic properties, with numerical predictions validated against laboratory measurements. A two-step global sensitivity analysis is then performed to identify the dominant parameters. The Morris method is initially applied to screen mechanical, acoustic, and geometric variables, followed by the computation of Sobol indices to quantify the influence and interactions of the retained parameters. Given the high computational cost of Sobol analysis for complex models, several metamodeling techniques are evaluated, including Polynomial Chaos Expansion, Kriging, and Polynomial Chaos Kriging (PCK). Among these, PCK is shown to provide the most accurate and efficient framework for estimating sensitivity indices. Finally, an optimization procedure based on a genetic algorithm is conducted on the micro-macro model of polyurethane foams, focusing on controllable material parameters. The results emphasize the critical role of the reticulation rate in enhancing the sound transmission loss of extended roller shutter boxes.
In this study, lightweight membrane-type acoustic metamaterial with flexible and hierarchical structures are proposed to enhance the low-frequency sound insulation performance. Numerical and experimental analyses are conducted on the five models with identical mass in two classes with varying geometries. The sound transmission loss and modal characteristics of the membrane-type acoustic metamaterials are analyzed using the FEM. This analysis provides insight into their acoustic and dynamic behavior in the low-frequency range. The finite element simulation results are validated through reverberant-anechoic testing using a 3D-printed prototypes of the model I and Model II. Modal analysis demonstrated the influences of different geometries on the sound insulation performance. The models with complex geometry (including: Model I, Model II, and Model V) resulted in higher eigenfrequencies in high-order modes, which was caused by their rigidity. In contrast, uniformly spaced eigenfrequencies were observed in some other models including Model III, which exhibited more fluctuations in sound transmission loss across the low-frequency range. Peaks in sound transmission loss mainly occurred around the eigenfrequencies. The first resonance region corresponds to the first eigenmode, resulting in a sharp drop in the sound transmission loss curve. Furthermore, the first peak and the majority of high sound transmission loss values occurred in the anti-resonance regions. Model II presented high sound transmission loss performance in the range of 140-350 Hz, whereas Model I achieved better performance in the range of 350-1500 Hz. Superior performance in Class 2 was achieved by Model V in the ranges of 100-200 Hz and 350-700 Hz. Overall, MAM samples showed an enhancement of 14-22 dBA in sound transmission loss compared to conventional materials, such as rockwool and polyethylene acoustic foam. Statistical calculations show a relatively small difference between the numerical simulation and experimental test. This work demonstrates that lightweight membrane-type acoustic metamaterials can achieve high sound transmission loss in low-frequency ranges without any need to increase the wall mass, through optimized geometrical design.
A locally resonant sonic crystal made of acoustically coupled concentric C-shaped cavities is proposed that generates multiple band gaps for usage as ventilated noise barrier. There is lack of comprehensive theoretical model for acoustic response of such concentric resonators, because the inter-scatterer coupling and variations in scatterers' opening and orientation angles introduce complex nonlinear effects. A semi-empirical theoretical model is proposed and validated for central frequency and bandwidth of the first band gap (BG) of proposed structure. Large-scale numerical analysis evaluates the impact of these angles, and a Kriging-assisted multi-objective genetic algorithm is developed to tune these angles for achieving a target BG with broadened bandwidth. Smaller opening angle and orientation misalignment lowers the central frequency and vice versa, whereas bandwidth varies nonlinearly. Experiments show multiple tunable transmission loss peaks above 20 dB within 1500 Hz, demonstrating a dimension invariant approach for tuning the sound attenuation of this sonic crystal.
This study reveals a critical discordance between technically compliant classroom acoustics and student perceptual comfort, demonstrating that compliance alone does not ensure adequate learning environments. Four Italian classrooms were assessed using ODEON acoustic simulations, standardized in-situ measurements, and perceptual evaluations involving 90 students. Results exposed disparities between objective and subjective performance: one classroom achieved acceptable Speech Transmission Index values (STI = 0.672) yet received negative comfort ratings, while another showed poor technical performance (STI = 0.453) but excellent satisfaction. High T30 calibration errors correlated with elevated perceptual disturbance. Anthropophonic noise emerged as the dominant acoustic concern affecting learning comfort. A novel perception-based priority ranking system was developed, integrating student comfort scores, disturbance assessments, and soundscape descriptors with traditional acoustic metrics. This methodology identified critical priorities overlooked by conventional assessments, with priority scores ranging from 1.58 for the most critical classroom to -0.90 for spaces where satisfaction was high despite technical deficiencies. Acoustic corrections were validated through ODEON simulations, with T30 calibration accuracy ranging from 83.3% for best-performing classrooms to 16.7% for the highly reverberant untreated environment, where interventions represent directional improvement trends. STI values increased by up to 66.7% in critical interventions, while targeted treatments achieved optimal conditions with minimal disruption to existing positive experiences. This research establishes that effective classroom acoustic design requires systematic integration of user experience with technical parameters, providing a replicable methodology moving beyond regulatory compliance toward genuinely comfortable learning environments, conducted within the necessARIA project funded by the Italian Ministry of Health as a national interest initiative.
Accurate prediction of heavy-weight floor impact sound in concrete apartments is essential for minimizing residents' exposure to low-frequency noise, which can significantly affect health and quality of life. This study investigates an improved finite element analysis (FEA) modeling approach by accurately reproducing the dynamic stiffness of resilient materials in floating floor systems. The elastic modulus and dynamic stiffness of four types of resilient materials were experimentally measured using a universal testing machine (UTM) and ISO 9052-1 testing methods, respectively. These values were then used in an FEA model developed in COMSOL Multi-physics. The results demonstrated that conventional input methods, where the elastic modulus is obtained by multiplying the measured dynamic stiffness by material thickness, led to an overestimation of 175.2% compared to the actual measured values. To improve accuracy, a correction factor was derived, adjusting the input elastic modulus to 60%-66% of the measured dynamic stiffness multiplied by thickness, which reduced prediction errors to within 0.6 MN/m(3). When applied to heavy-weight floor impact sound prediction in actual apartment buildings, this method improved prediction accuracy by up to 48.1% (RMSE criterion) compared to conventional approaches. These findings highlight the importance of accurately defining material properties in FEA simulations for floating floor systems to prevent low-frequency amplification effects and optimize sound insulation performance.
The room acoustics design of concert halls plays an important role in sound quality, and machine learning has been proposed as an advanced approach for predicting room acoustics. However, previous studies often use geometric (such as length, width, and height) and material parameters as features, resulting in high accuracy but limited generality when applied to different room types. Hence, this study proposed a machine learning based parametric design framework on the Rhino-Grasshopper platform. The approach used distributed equivalent absorption areas as features by considering the importance of the first reflection in concert halls, thus improving generality in the early design stage. Trained on a dataset combining two different types of concert halls, the fivefold cross-validation results demonstrated that the Mean Absolute Percentage Error (MAPE) for Reverberation time (T30) and the Root Mean Square Error (RMSE) for both Clarity 80 (C80) and Sound strength (G) remained within 1 Just Noticeable Difference (1 JND). The high accuracy highlights the advantages of this framework in comparing different types of concert halls and broadens the capability of architects to optimize design proposals in the early design stage.
Ensuring acoustic comfort in educational environments is crucial for both pedagogical efficiency and user health. This study examines the acoustic performance of a newly constructed university research center in T & uuml;rkiye, in line with the criteria set out in the "Regulation on the Protection of Buildings Against Noise." Unlike most studies in the literature, which generally rely on post-occupancy measurements, this study offers a proactive evaluation method by integrating on-site environmental noise measurements (Leq) with detailed sound insulation simulations (KS Schallschutzrechner) in a building that is still under construction. Analyses show that, while the building's location meets environmental noise limits (41-54 dBA), which is well below the 65 dBA threshold, the internal partition elements are insufficient to meet legal requirements. Quantitative findings reveal that using curtain wall systems (Rw: 33 dB) and MDF cabinets integrated into partition walls results in acoustic performance being approximately 10-15 dB below regulatory limits. Furthermore, excessive volume imbalances between corridors and workshops and the failure to design auditoriums as enclosed spaces were identified as the primary causes of acoustic failure. The study concludes with evidence-based design recommendations to bridge the gap between architectural design decisions and regulatory compliance, such as the use of high-performance laminated glass and optimized material placement. This research provides architects and consultants with a repeatable performance review model to ensure acoustic standards are met before completion of the building.
Current indoor acoustic models mainly use sound pressure level cutoffs or occupant surveys, missing an interpretable, multi-factor index that links objective metrics with perceived indoor acoustic conditions. This paper introduces a fuzzy-logic Acoustic Comfort Index (ACI) that integrates six inputs: sound pressure level, dominant frequency, emission pattern, masking condition, acoustic criticality, and noise variability, into a continuous 0-1 score (lower indicating greater comfort) with categorical interpretation. The framework is conceptually informed by the ISO/TS 12913 soundscape paradigm, emphasizing contextual and perceptual aspects without relying on survey-based inputs. A 2025-rule Mamdani system is generated through automated rule construction. Model benchmarking includes 1000 randomized cases and 16 representative indoor scenarios. Local sensitivity analysis quantifies variable influence, while a ridge-regularized GAM surrogate confirms expected monotonic behavior and yields strong hold-out agreement. PCA clustering identifies comfort regimes that support practical diagnostic use. Benchmarking against SPL-only and reduced models illustrates the added value of contextual and perceptual variables. A MATLAB ACI Calculator App enables practical application from direct inputs or audio recordings, with calibrated inputs used for absolute SPL estimation.
In this study, the researchers offer an interior design framework of incorporating principles of smart technology and the healing environment to improve quality of life of aging populations. The framework is aimed at enhancing the safety, comfort, emotional stability and general acceptance of the living conditions. The proposed design was evaluated by carrying out a structured survey with 60 respondents in an independent and assisted living setting. The mean scores of safeties = 3.348, comfort = 3.194, healing = 3.584, smart technology = 3.11 and acceptance = 3.0175 showed moderate to positive perceptions of the design elements. One-sample t-tests established that the response in all domains was significantly greater than baseline test value of 3 (p < 0.001), and the effect size analysis indicated that the effect is moderate to large especially in the healing (Cohens d = 1.319). The regression analysis showed that smart technology (0.531, p < 0.001) and healing environment features (0.359, p < 0.001) had a significant impact on predicting safety perception. The analysis of reliability showed a good internal consistency of the survey sections with Cronbach alpha of greater than 0.73. These findings indicate that the framework has managed to integrate functional technology with biophilic and restorative design features thus offering a supportive, safe and emotionally nurturing environment. The framework provides an effective tool of designing aging-friendly interiors that are balanced in terms of physical, cognitive, and emotional needs that are likely to improve the well-being and quality of life among the aging populations.
The traffic noise model embedded in ISO 717-1 was originally developed with the 1980s Nordic traffic data, raising concerns regarding its applicability to the contemporary traffic situation. This study conducted field measurement of current traffic noise on representative urban roadways to evaluate the suitability of these legacy rating criteria. Results showed that modern traffic noise spectra exhibited significant divergence from the ISO reference, with discrepancies reaching up to 10 dB at 100 Hz. When applying both spectral datasets to assess the sound insulation performance of windows and composite wall systems, the standard exhibited a consistent tendency to overestimate low-frequency energy components while simultaneously underestimating the actual performance of building elements. Finally, psychoacoustic analysis revealed that the proposed spectral correction term failed to yield a stronger correlation between the sound reduction index and subjective perception compared to the existing reference curve. Collectively, these findings suggest that more accurate traffic noise spectrum corrections should not be rely exclusively on the source characteristics, but must additionally account for human auditory perception mechanisms to maintain their validity.
The ruins of the church of Saint Pantaleon, located in the historical center of the city of Cuenca (Spain), presents a Romanesque origin related to the Order of the Temple and a Gothic finish. Moreover, the two naves of which it would consist in the 13th century, would become a single one in the 16th century. Through the analysis of the ruins and the investigation of the architectural and stylistic characteristics of the period, as well as the comparison with other temples in Spain, two simulation models have been made for the 13th and the 16th centuries respectively. They have been validated by comparison with studies of temples of similar contexts and dimensions due to the impossibility of validating the model with in-situ measurements. As the observed behaviors are analogous, it indicates that the theorized models are accurate and, therefore, the results are reliable. These models, were simulated in an occupied and empty state for officiant, choir and populus sources. It can be highlighted a more reverberant enclosure in the 16th century, with better values of vocal clarity and definition and better intelligibility than in the case of the 13th century model. Regarding positional differences, it has been observed that there are hardly any differences among the three positions in any of the models. Finally, the inclusion of the audience has a remarkable effect on the acoustics due to the increase of absorption, which leads to a better musical clarity, definition and intelligibility and a shorter reverberation time.
The diversity of architectural forms, together with the materials used, fundamentally determines how sound behaves in enclosed spaces. While previous research has predominantly focused on the acoustics of complex, historically or functionally specific buildings, it has given limited attention to the elementary volumetric forms that constitute the basis of architectural design. This study investigates the acoustic behavior of 20 generative geometries, ranging from basic primitives to long rooms, coupled spaces, and sequential volumes, that common architectural typologies. Room impulse responses are examined in a controlled setup through both ray-tracing simulations and the diffusion equation model (DEM). T30 values and relative sound pressure level (SPL) differences are systematically compared, and DEM is further employed to visualize time-dependent energy flow, revealing how form itself governs patterns of sound distribution. Material variations are introduced to assess the impact of inhomogeneous absorption, while a pilot field measurement in a corridor validates long-room acoustical predictions. By re-examining sound propagation in simplified forms, this research establishes the acoustic potential of architectural form as a primary design parameter, offering a framework that bridges methodological innovation with design practice in the early stages of acoustically informed architecture.
Low-frequency floor-impact noise is the principal acoustic shortcoming of cross-laminated-timber (CLT) construction, yet current single-number ratings are rooted in tapping-machine spectra and under-represent heavy/soft human impacts below 100 Hz. We couple a validated plate-beam finite-element model of a two-story CLT test building to a rectangular room-acoustic model and generate 12 auralized stimuli-three slab thicknesses (150, 210, and 270 mm) with and without mid-span and quarter-span beams, each excited by literature-based jump-type (1.2 kN, 20 ms) and run-type (0.6 kN, 30 ms) forces. The frequency-domain responses are converted to time waveforms via inverse FFT and reproduced, after full transfer-path equalization, to 20 normal-hearing adults in a semi-anechoic room. Psychophysical scaling employs magnitude estimation (ME) for all stimuli and paired comparison (PC) for the six jump-type cases, while the objective descriptor is the event maximum level LAFmax (ISO 717-2:2020, Annex D). Beam integration lowers LAFmax by 1.9, 1.3, and 5.9 dB for the 150, 210, and 270 mm slabs, respectively, with a mean reduction of 3.1 dB; thicker slabs are consistently quieter than thinner ones. ME geometric means correlate strongly with LAFmax (r = 0.88, semi-log fit, R2 = 0.77), and the PC loudness scale shows a comparable association (r = 0.85, R2 = 0.73), confirming that event-level attenuation translates directly to perceived quietness. Results demonstrate that beam integration is an effective structural lever for sub-100 Hz impact noise and that LAFmax, evaluated on simulation or rubber-ball tests, provides a perceptually grounded design metric that complements conventional ratings.
Environmental comfort, particularly acoustic comfort, plays a crucial role in patient satisfaction within healthcare facilities, especially in sleeping wards. This study aims to optimize hospital acoustic performance to meet recommended noise levels. It defines key acoustic parameters and uses computer simulations to develop solutions that minimize the impact of external noise sources. Results indicate that optimizing window placement and type, applying acoustic insulation treatments, and using multi-layered wall materials significantly reduce noise levels. The study emphasizes the importance of integrating acoustic comfort in hospital design to improve overall healthcare quality. It offers practical guidelines for intervention during the design phase of hospitals and provides valuable insights for architects, engineers, and policymakers to create acoustically optimized healthcare environments.
The trend of increasing the ratio of environmentally friendly solutions in the building industry is on the rise. We increasingly encounter solutions that utilise loose-form materials or, to improve thermal insulation and acoustic properties, typically multilayer lightweight systems. However, it has been proven that predicting the impact of loose-form blown-in materials on sound insulation properties can be a matter of debate. Blown-in materials with a higher bulk density tend to connect the individual layers of lightweight walls mechanically. It is not trivial to accurately determine the stiffness of the blown-in material after application in the building structure. This is especially important when creating prediction models. This paper deals with the determination of the dynamic stiffness of soft materials using the light load plate and two degrees of freedom (2-DOF) method. Since the case of evaluating resilient materials at low loads is outside the recommended range of boundary conditions as defined by EN 29052-1, this extensive work gradually analyses the relevance of applying an alternative measurement method. It discusses the effect of compression of a soft material on its actual dynamic stiffness, the effect of the excitation form of the light load plate, and presents a preliminary measurement approach. Numerical models support individual analyses and measurements. Even though testing fibrous materials in loose form is a very challenging task, a significant change in stiffness under the influence of loading has been demonstrated.
The multilayer sound absorber (MSA) is typically a composite structure that consists of a micro-perforated panel (MPP) with circular perforations, a layer of porous material, and an air gap. This combination enhances the sound absorption coefficient (SAC) across a broad frequency range. However, the sound absorption mechanisms of the MSA when incorporating polygonal cross-section perforations have not been thoroughly investigated. In this paper, the acoustic impedance of MPP with square or equilateral triangular cross-section perforations is simply given based on a complex density function and the radiation impedance in short tubes with square cross-sections. Theoretical acoustic impedance models are established for three configurations: CMSA (circular perforations), SMSA (square perforations), and EMSA (equilateral triangular perforations), using the transfer matrix method (TMM). To validate these models, SAC measurements were conducted via an impedance tube, showing good agreement with theoretical predictions. Further analysis of the acoustic performance revealed that the SMSA configuration exhibits a higher resonance peak and a broader absorption band. Finally, a simple optimization of the hole diameter and air gap was performed using an oppositional Runge Kutta optimizer with cuckoo search (OCRUN). The results demonstrate that the EMSA achieves quasi-perfect sound absorption within specific frequency bands using a smaller air gap compared to both CMSA and SMSA.
