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.

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 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.

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.

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.

Acoustic textiles are the most widely used acoustic materials to control room acoustic parameters in current practice. Based on porous acoustic absorption, they are able to achieve high absorption at middle and high frequencies. This behaviour is a limitation for spaces that host speech comprehension or activities that require concentration. For this reason, acoustic sector companies tend to explore the advancements in other sectors (e.g. technical apparel, transportation, etc.) to find solutions that can satisfy this requirement. This is the case of 3D spacer fabrics (3D SFs) which, thanks to the two horizontal layers and the internal connecting vertical pile, have complex and customisable structures adaptable according to the acoustic performance (absorption, reflection, diffraction). Originally developed to provide sound insulation in transportation vehicles, these materials’ acoustic performance has been explored, but a comprehensive and updated research review is lacking. In response, this paper presents a systematic review aiming to understand the correlation between the physical characteristics of these materials and their acoustic performance. The review is based on the literature of the last 10 years of reviewed and published papers. Absorption coefficients are gathered, sorted and compared with the most extensively used acoustic materials. This contribution shows that the main performance analysed is absorption and this depends on thickness, porosity, and flow resistivity of the horizontal layers. The complex pile structure of 3D SF enables absorption coefficients that are comparable with the most common acoustic materials. The analysed references are based on literature absorption coefficients measured in an impedance tube. Future research should explore the possibilities of 3D SF application at an architectural scale by analysing the absorption coefficients in a reverberant chamber or by analysing reflection and diffraction behaviours.

Noise is a major challenge in open-plan offices, where irrelevant speech, casual conversations, phone ringing, and discussions frequently disrupt productivity, increase stress, and reduce overall workplace comfort. Common solutions to mitigate these issues include sound-absorbing surfaces and noise-reducing partitions. Meanwhile, green solutions—such as green roofs and vertical green systems—have been developed to integrate vegetation into the built environment, offering benefits like stress reduction, improved air quality, and enhanced mental well-being. These systems can also boost employees’ cognitive performance, further increasing productivity. However, indoor green walls can also reduce noise pollution and sound transmission in enclosed environments. Therefore, this study aims to address noise transmission in open-plan office environments by evaluating the effectiveness of a vertical green system as a noise-reducing partition. The study was conducted by testing a modular green wall system measuring 1.28 × 1.28 m under four different vegetation coverage conditions (bare, 1/3, 2/3, and full coverage). The results demonstrated that with full vegetation coverage, there was a noticeable reduction in sound pressure levels across most frequencies compared to the bare condition. The highest insertion loss (IL) was observed at 1250 Hz, measuring 16.2 dB. Additionally, increasing vegetation coverage was associated with a decrease in sound pressure levels across most frequencies.

After the World War II, Albania was governed by a dictatorship that lasted for about 50 years. The cultural life restarted to be one of the main centers of the society community. Many buildings styles reflected the influence of governors as leaders of countries, in combination with the spread of armed concrete used as the main material for new constructions, given its flexibility compared to brickwork that was not yet developed as it is nowadays. In Albania, many cultural centers were constructed for the local community where citizens can have access to libraries, coffee shops, and auditoria. These latest ones represent the places where live shows are performed, along with international conferences. This paper deals with the assessment of the acoustic response gathered within three auditoria as part of cultural centers in Albania. The acoustic measurements were carried out in accordance with ISO 3382-1. The acoustic response recorded inside the three case studies indicate a good listening condition for both speech and music performance. This outcome has been found in all three auditoria, despite the room volume between each other is different.

Laboratory and field measurements of the impact sound acoustic performance of a CLT wood-based floors have been performed. French national regulation requires the use of the standardized tapping machine for impact sound performance measurements. Since the early 2000s, rubber ball impact source has been standardized in some Asian countries to measure and evaluate the low frequency impact sound performance of floors; this excitation source is now part of international standards concerning building acoustic measurement in laboratories and in-situ. Indeed, the impact sound level associated to this soft impact source is supposed to provide a better correlation with annoyance from jumping and/or running children in buildings. The paper reviews the measurements performed using the standard tapping machine and the rubber ball as impact source, on CLT based floors in a laboratory, as well as those on the CLT based experimental building. Impact sound improvements are presented and discussed. The necessity of measuring with both impact sources, rather than only with the tapping machine is examined.

Preschool is an important time for children to grow in their experiences, abilities, and knowledge before entering formal school. Therefore, it is vital that the classroom acoustic environment supports children’s listening, learning, and wellbeing. The aim of this scoping review was to determine what is known from the literature about the effect of classroom acoustics and noise on preschool children’s listening, learning, and wellbeing, and what the knowledge gaps are. The scoping review followed the PRISMA-ScR guidelines. Seven papers met the criteria to be included in the review. The findings suggest that poor classroom acoustic conditions and particularly high noise levels, can have a negative effect on preschool school children’s listening and wellbeing, but may not affect word learning at the SNRs investigated. Nevertheless, it would be beneficial to install acoustic solutions and manage noise in preschool classrooms to enhance children’s listening, learning, and wellbeing. Future research avenues are discussed.