Search Results (252)

Classroom acoustic quality plays a crucial role in speech intelligibility and effective learning. However, many existing classrooms suffer from excessive reverberation and insufficient speech clarity. This study investigates the acoustic regulation potential of oriented strand board (OSB) panels through a combined approach of field measurements and numerical simulations. A typical classroom was first characterized in terms of reverberation time and speech transmission index within the frequency range of 250–2000 Hz. Based on previous acoustic performance tests of OSB materials, 15 mm thick OSB panels were selected for further spatial layout optimization. Three installation configurations with identical material quantities were designed and evaluated using COMSOL Multiphysics 6.2 simulation. The simulation results were subsequently validated through in situ measurements. The results indicate that the distributed installation of OSB panels on both the side and rear walls provides the most balanced acoustic performance, reducing reverberation time from approximately 1.55 s to 1.42–1.48 s, while increasing the speech transmission index by 1.8–9.4%. This study establishes a layout-oriented acoustic design framework that explicitly integrates material performance with spatial configuration, highlighting spatial distribution as the dominant control variable under constrained material conditions. These findings provide practical guidance for cost-effective acoustic retrofitting in educational buildings and demonstrate the effectiveness of layout-oriented acoustic design strategies. Full article

This study examines the potential of sustainable, biobased paper-based structures as panel/membrane sound absorbers. Although intact paper is naturally impermeable and a poor sound absorber, transforming it into complex three-dimensional origami geometries, specifically the Miura-ori pattern, could produce effective panel/membrane absorbers. Three distinct Miura-ori samples (A, B, and C) were fabricated with increasing geometric complexity, ranging from a simple triangular prism to a complex labyrinthine waveguide. The random incidence sound absorption coefficients of these samples were measured in a validated small-scale reverberation room. The underlying absorption mechanisms were further investigated through modal analysis and non-contact vibration velocity measurements. The results indicate that increased geometric complexity enhances acoustic performance. Sample C, the most complex structure, demonstrated the most consistent broadband absorption. The analysis confirmed a significant positive correlation between acoustic pressure modes, surface vibration velocity, and sound absorption peaks, indicating that acoustic energy dissipation is driven by the vibrational response of the paper membrane coupled with resonant modes in the air gap. This research demonstrates that tunable origami folding techniques using intact paper can be used to design lightweight acoustic treatments for diffuse sound fields in the mid-frequency range. Full article

Comprehensive room acoustic characterization requires resolving reflection behavior across time, frequency, and space. The recently proposed eigenbeam–vMF-based analyzer provides a framework for this by modeling the reflection field as a time–frequency-dependent directional power distribution, estimated via spatial correlation of eigenbeams (ambisonics) and parameterized using von Mises–Fisher clustering. This formulation enables a unified and interpretable description of anisotropic early reflections, their transition into diffuse reverberation, and frequency-dependent acoustic behavior. Prior work showed that the analyzer reliably captures these features using higher-order ambisonics from a 32-channel spherical microphone array (SMA) and that constraining the same array to the first order still led to retaining the dominant features. This paper investigates whether this capability extends to first-order microphone arrays with sparser spatial sampling for more economical and practical deployment. A comparative study is conducted in a recording studio with variable wall panels (wood and felt), evaluating a four-channel first-order array against a 32-channel SMA. The results reveal distinct acoustic differences between panel settings, which are consistent across both arrays. While the SMA captures finer spatial detail and prolonged anisotropic reflections more effectively, the first-order array demonstrates potential for preliminary room acoustic assessments by identifying room mode frequencies, dominant reflection directions, and highly reflective surfaces. Full article

The Real Maestranza de Caballería in Seville features one of the most prominent Spanish bullrings, characterized by a notable architectural design. Its distinctive ovoid geometry resulted from a protracted construction history (1761–1881), during which the floor plan adapted to pre-existing urban structures. Beyond its architectural significance, the sounds perceived within such venues constitute traces of collective memory and form part of an intangible cultural heritage relevant for understanding the sociocultural context of such spaces. This work provides an acoustic characterisation of the bullring through field measurements. Reverberation time and other monaural and binaural descriptors were determined using 3D impulse responses obtained from strategically placed sources and receivers. This analysis is complemented by examining the sound energy distribution of early reflections in the time–frequency domain to define the acoustic signature of the venue, namely the characteristic pattern of early reflections that unequivocally determines its sound response, and identify the provenance of reflections. In the Maestranza, music and silence are hallmarks of its identity, contributing to a complex auditory environment. The results highlight how its geometry and tiered seating create a differentiated sound field, potentially contributing to the preservation of the site as a cultural landmark. Full article

Sound field reproduction (SFR) is vital for noise simulation and acoustic comfort optimization in vehicle cabins. This paper reviews three core SFR techniques: Wave Field Synthesis (WFS), Higher-Order Ambisonics (HOA), and Pressure Matching (PM). Their theoretical fundamentals, engineering optimizations, and adaptability to narrow enclosed cabins are analyzed. We compare the three methods in terms of reproduction accuracy, system complexity, and cost. Key challenges in vehicular applications are summarized, including strong reverberation, multi-source coupling, and the mismatch between physical reproduction and subjective perception. Future directions are proposed, such as physics-data hybrid optimization, low-cost lightweight design, and personalized acoustic comfort. This review offers a practical reference for the engineering application of SFR in vehicle cabin acoustic optimization. Full article

Diocletian’s palace with its cellars represents one of the most important cultural heritage sites of the ancient Roman civilisation on the present-day Croatian territory. The cellar complex has been rediscovered only recently and has been preserved remarkably well due to its centuries-long concealment beneath mediaeval urban matrices. An archaeoacoustic analysis was performed on a selected single-nave hall as a small part of this complex. A model of the hall was developed in room acoustics simulation software and calibrated based on the results of field measurements. Acoustic suitability of the hall for speech-based events and music performances was then evaluated according to contemporary objective criteria, and the findings were compared with the results of similar studies performed on other heritage sites. The hall was found to be very well suited for speech in terms of intelligibility and mid-frequency reverberation, thus showing potential for revitalisation, with excessive low-frequency reverberation in the hall and reduced audibility in the farthest part of the audience as potential issues. With a feasible audience size, the hall is not reverberant enough for music performances but provides high clarity. In terms of sound strength, the hall is suitable for solo performers or small ensembles. Excessive perceptive broadening of the sound source is expected due to strong early lateral energy. In terms of traditional Dalmatian a cappella singing, the acoustics of the hall are likely to support and enhance such performances. Full article

The building façade serves as the primary interface between the built environment and external climate, marking the transition from static regulation to dynamic response in climate-adaptive design. While existing research predominantly addresses periodic climatic elements such as temperature and solar radiation, the highly stochastic wind environment and its potential for internal acoustic problems remain systematically unexplored. This study investigates the acoustic modulation mechanism of building façades under dynamic wind conditions through a simulation-based methodology. The primary aim is to demonstrate the use of active control to mitigate the influence of fluctuating wind on the internal acoustic environment of buildings with open windows or semi-open boundaries, focusing on the coupling between stochastic wind fields and architectural acoustics in humid subtropical climates. We propose a wind-responsive adaptive acoustic façade system employing fractal geometry and configurable delay strategies, and develop a high-fidelity simulation framework to quantify how façade geometry and activation logic regulate acoustic parameters under varying wind conditions (1–8 m/s). Results indicate that: (1) support vector regression-based mapping of wind speed to delay strategies maintains key sound-field parameters (Lateral Fraction (LF), Speech Clarity (C₅₀), and Early Decay Time to Reverberation Time ratio (EDT/RT₃₀)) within 10% fluctuation across wind regimes; (2) fractal configurations achieve balanced wide-band (125 Hz–8 kHz) performance, with SPL fluctuation <3 dB, spectral tilt (+0.3 dB), and reverberation time slope <0.3; (3) configurational switching between column (high LF) and row (high C₅₀) arrangements enables dynamic trade-off between spatial impression and speech clarity. This work establishes an integrated framework coupling wind dynamics, façade morphology, and acoustic modulation to regulate objective indoor acoustic parameters. Based on the simulated omnidirectional point-source model, the results show that key acoustic indicators remain stable across varying wind conditions, providing a theoretical and quantifiable basis for climate-responsive acoustic envelope design. Future work will include empirical prototype testing and listening tests to determine whether these simulated acoustic parameters translate into improved comfort and well-being for occupants. Full article

This study examines noise levels and acoustic quality in preschool learning spaces in Taiwan, using a validated protocol from prior research in New Zealand. Seventeen classrooms across six centers, primarily in the major city of Kaohsiung, were assessed using acoustic measurements, personal dosimetry for teachers and children, and a structured teacher questionnaire. Most classrooms exceeded recommended reverberation time thresholds, and none met optimum acoustic standards. Fixed sound level meters substantially underestimated noise exposure during active periods compared to personal dosimetry. Dosimetry revealed that 24% of children and 27% of teachers experienced daily noise dose above 100% of the occupational criteria used in New Zealand and Europe. Notably, a center with a distinct educational philosophy demonstrated markedly lower individual exposure despite high ambient levels. These findings highlight systemic gaps in acoustic regulation for early childhood education in Taiwan and raise broader concerns about the default of using adult-based noise criteria for young children. Recommendations include Taiwan adopting or developing suitable acoustic standards and guidance values for noise levels in classrooms. The results have implications beyond Taiwan, offering evidence relevant to global efforts to improve preschool learning environments. Full article

The growing demand for noise reduction in multi-joint long-reach robotic arms necessitates the development of precise noise measurement methodologies. However, accurate characterization remains challenging due to the robot’s complex kinematics. Specifically, dynamic joint positions and motion trajectories can lead to acoustic occlusion, while the inherent directivity of sound sources further compromises measurement reliability. To address these issues, this study proposes a component-based hybrid measurement approach. First, the noise generated by a single joint was characterized using a simplified 4-point method, with Green’s function applied to correct for variable propagation distances. Subsequently, the total sound power level of the entire robotic arm was synthesized in a virtual environment by integrating the single-joint acoustic data with the arm’s operational kinematic program. Validation results demonstrate that the proposed method achieves a measurement error of only 0.8 dB relative to the reverberation chamber benchmark—an accuracy superior to that of direct measurements of the full robotic arm cycle (2.6 dB). Furthermore, a comparison with the ISO 3744:2025 9-point standard method reveals that while the proposed 4-point approach yields a slightly larger error (0.8 dB vs. 0.2 dB), it significantly reduces experimental complexity. Consequently, this method offers a sufficiently accurate and operationally efficient solution for practical engineering applications. Full article

This study investigates the sound insulation performance of an anechoic chamber, exploring the influence patterns of different multilayer material combinations on wall sound insulation characteristics. Based on sound transmission theory, a predictive model for multilayer material wall sound insulation was established. The finite element method was employed to simulate the sound propagation characteristics of walls and glass doors with various material combinations. After validating the simulation results through a double-room method experiment, the material combination scheme for the anechoic chamber walls and glass doors was optimized. Based on this, a 1000 mm × 1000 mm × 2300 mm soundproof room prototype was designed and constructed. Its sound insulation performance under reverberant conditions was tested using the insertion loss method and compared with simulation data. Simultaneously, a hybrid calculation method combining low-frequency finite element analysis with high-frequency statistical energy analysis enabled precise and efficient prediction of the overall sound insulation performance of the soundproof room. Research revealed that single-pane glass with thicknesses between 5 and 20 mm conformed to the mass law, with sound insulation increasing by an average of 0.8 dB per additional millimeter. The 10 mm single-pane glass emerged as the optimal choice for the soundproof room’s glass door due to its ideal thickness and excellent low-to-mid-frequency sound insulation. The optimized wall structure featured compact thickness, outstanding low-frequency sound insulation, and balanced mid-to-high-frequency performance. Simulation and experimental results for the core frequency range of 63–1000 Hz showed high consistency, which validates the reliability of the theoretical model and simulation methodology within this frequency band. The deviation of simulation results from experimental data in the frequency range above 1000 Hz is mainly caused by acoustic leakage due to experimental sealing defects, and the high-frequency simulation results are only used for trend analysis rather than conclusion support. This study identifies the optimal multi-layer material combination for soundproof rooms, providing practical material strategies for acoustic design. It also reveals the sound insulation mechanisms of multi-layer composite structures. The findings offer significant reference for optimizing soundproofing materials and structures in architectural acoustics and transportation noise control. Full article

Detecting violent content in audio recordings is crucial for public safety, autonomous surveillance, and content moderation, particularly when visual cues are unreliable or unavailable. A resource-aware two-stage cascade system is proposed for acoustic violence detection that combines a lightweight Least Squares Linear Detector (LSLD) as a first-stage screener with a trimmed version of YAMNet as a second-stage classifier. A percentile-based forwarding rule controls the fraction of segments routed to the deep stage, turning the accuracy–cost trade-off into an explicit operating parameter for always-on deployment. The approach is evaluated on a publicly released dataset of real-world violent audio augmented with background noise and artificial reverberation. The results in the low-false-alarm regime show that the proposed cascade preserves performance close to a Stage 2-only baseline while substantially reducing average deep-inference workload. An ablation study validates the role of the LSLD as an inexpensive pre-filter, and robustness is assessed under clean, reverberant, and 12 dB noise conditions. Finally, an analytic energy consumption model is provided, which links computational workload to daily energy demand and photovoltaic sizing on ultra-low-power hardware, supporting sustainable off-grid deployment. Full article

Enclosed learning spaces, e.g., classrooms, are used in most schools. Open learning spaces, which enable teaching more than one group of students at a time, have become increasingly popular. A recent survey showed that acoustic satisfaction was lower among teachers working in open learning spaces. Our purpose was to compare the acoustic conditions of these learning space types. We investigated the room acoustic quality of 73 learning spaces in 20 schools. Ten schools involved only enclosed and ten both open and enclosed learning spaces. Measurements concerned speech transmission index, STI, background noise level, L_Aeq, and reverberation time, T. Variation in results in both learning space types was rather large. In enclosed learning spaces, STI varied within 0.64–0.83, L_Aeq within 25–47 dB, and T within 0.34–0.82 s. The corresponding variations in open learning spaces were 0.47–0.91, 29–44 dB, and 0.44–0.72 s. The differences between enclosed and open learning spaces were surprisingly small. Due to the different intended uses of these space types, Finnish target values are tighter for open than for enclosed learning spaces. These target values were fulfilled in 56% of enclosed and 9% of open learning spaces. The more frequent violation of target values in open learning spaces was due to the STI being too large at longer distances. Our study provides suggestive evidence that the room acoustic conditions are worse in open than enclosed learning spaces. Further research is needed to prove whether room acoustic conditions could explain worse acoustic satisfaction in teachers. Full article

The Church of St. Francis in Pula, Croatia, is a well-preserved example of Franciscan gothic sacral architecture from the late 13th century. As preaching was highly valued by the Franciscan order as a way of communicating with the faithful, the study is focused on determining whether speech intelligibility in the church would have been adequate for successful communication between priests and their audience. The archaeoacoustic analysis of the church was performed in four stages: (1) in situ acoustic measurements in the present state, (2) development and calibration of the model of the present state based on measurement results, (3) development of the two models of the presumed historical state based on the calibrated model and historical data, and (4) prediction of acoustic conditions in the present and the historical states in terms of reverberation time T₃₀ and of speech intelligibility in terms of speech transmission index STI. The factors considered in the study were (1) acoustics of the church, (2) profile of the audience (friars and the faithful), (3) layout of the audience areas (choir area in the front of the nave for the friars, back area of the nave for the faithful), (4) positions of the speech sources (altar for addressing the friars, pulpit for addressing the faithful), (5) occupancy (unoccupied and fully occupied church), (6) language used in liturgical ceremonies (Latin and native language), and (7) language proficiency of the audience (native speakers, users of a second language). The results show that (1) fair speech intelligibility (STI ≥ 0.45 for the faithful as native speakers, STI ≥ 0.50 for friars as non-native speakers of Latin) can be achieved for 50% of the audience in the choir area and for the entire audience in the back area in favourable conditions (fully occupied church, audience addressed from dedicated speaker positions), (2) the position of the pulpit (close to the audience and considerably elevated above it) is more favourable than the position of the altar (remote, barely elevated above the audience), and (3) in unoccupied conditions, fair speech intelligibility can still be achieved in at least 50% of the back audience area with the faithful gathered close to the pulpit, while it is not possible for the front audience area addressed from the altar. The summary conclusion is that the church of St. Francis in its presumed historical layout(s) would fulfil its primary function in a limited capacity. Fair speech intelligibility would likely have been sufficient for the audience to follow liturgical ceremonies conducted in the church, but not without difficulty. Full article

Sound source localization in dynamic environments with multiple moving speakers presents significant challenges due to reverberation, noise, and unknown source counts. To address these issues, this paper proposes an integrated deep-learning framework combining spatial spectrum estimation with blind source detection. The method employs a causal convolution–recurrent network (SRP-DPCRN) to extract robust spatial features from multichannel audio signals under adverse acoustic conditions. Subsequently, an iterative attention-based detection network (IASDNet) automatically identifies active sources from the estimated spatial spectrum without requiring prior knowledge of source quantity. Evaluated on both simulated datasets and the real-recorded LOCATA benchmark, the proposed system demonstrates superior performance in multi-source tracking scenarios, achieving an average detection accuracy of 96% with mean angular error below 3.5 degrees. The results confirm that joint optimization of feature learning and source counting provides an effective solution for blind localization in practical applications, significantly outperforming conventional and deep-learning baselines. Full article

The acoustic design of outpatient halls is often ignored, yet the acoustic environment significantly impacts patients’ physical and mental well-being as well as their visit experience. This paper takes the outpatient hall of a hospital in South China as a case, employs in-situ acoustic measurement, and conducts a quantitative analysis of its indoor acoustic environment through acoustic simulation. The in-situ measurements show that the noise level, speech intelligibility and reverberation time in the hall all fail to meet standard requirements. The poor acoustic quality is mainly due to the lack of acoustic design. Consequently, this study proposes measures to improve the outpatient hall’s acoustic environment from two aspects, namely sound absorption and building form design. These measures include sound absorption treatment, adjustment of the hall’s floor height and optimization of planar length-to-width ratio. The redesigned outpatient hall plan demonstrates an evident enhancement in acoustic quality and validates the effectiveness of the proposed redesign strategy. This study can provide practical guidance for the design and acoustic renovation of healthcare buildings and can also offer new insights for the redesign of hospital outpatient halls from the perspective of improving the acoustic environments. Full article