Soundscape, defined as the acoustic environment as perceived or experienced by humans, has gained increasing attention due to concerns about the health impacts of urban noise. A key focus of recent audio-visual soundscape studies is the role of greenery in enhancing soundscape perception. Thus far, studies have primarily concentrated on the quantity of greenery, while much less attention has been given to its qualitative attributes such as species composition, spatial configuration, color, and aesthetic qualities. Moreover, existing work often relies on linear assumptions, potentially overlooking nonlinear relationships between environmental exposure and human responses. We addressed these knowledge gaps through two soundwalks in residential neighborhoods in Singapore involving 118 participants, with acoustic recordings and 360-degree photographs collected to characterize the acoustic and visual environments. Linear mixed-effects models (LMMs) and generalized additive mixed-effects models (GAMMs) were compared to examine relationships between visual landscape attributes and soundscape assessments. The results showed that GAMMs outperformed LMMs, indicating improved performance when nonlinear effects were considered. Landscape attributes, including wildness, visual depth, sky view index, and building view index, were found to be significantly associated with soundscape perception, with nonlinear relationships identified for wildness and visual depth. A turning point at 0.6 was observed in the relationship between wildness and soundscape quality, beyond which increases in wildness were associated with greater increases in soundscape quality. Sensitivity analyses confirmed the robustness of these findings. Overall, this study highlights the importance of moving beyond a sole focus on greenery quantity to consider its qualitative characteristics in soundscape research, thereby advancing understanding in this field.
This study examines how auditory contexts, or soundscapes, shape chocolate taste perception, affective response, hedonic liking, and the extent to which emotion mediates these effects. Using a within-subjects design with 120 participants aged 18-25 years, four auditory conditions were compared: silence, natural soundscape, relatively low-pitched soundscape, and relatively high-pitched soundscape. Participants evaluated perceived bitterness, sweetness, acidity, emotional valence, arousal, and overall liking after tasting the same 65% dark chocolate under each auditory condition. The results showed that auditory context significantly modulated taste perception, affective response, and liking. The natural soundscape produced the most favorable profile, increasing liking and emotional valence while reducing arousal. In contrast, the relatively high-pitched condition increased arousal and enhanced perceived acidity (Δ ≈ 6.77 VAS points). Effect sizes indicated stronger effects on arousal (partial η2 ≈ 0.46), liking (partial η2 ≈ 0.29), acidity (partial η2 ≈ 0.28), and valence (partial η2 ≈ 0.26) than on sweetness perception (partial η2 ≈ 0.05). Mediation analysis showed that emotional valence partially explained the relationship between the natural soundscape and liking, whereas arousal did not play a significant mediating role. These findings suggest that auditory environments influence chocolate evaluation through both affective and crossmodal pathways. Overall, the study provides controlled evidence that sound can function as a relevant contextual variable in multisensory chocolate-tasting experiences, with implications for sensory evaluation, gastronomy, and experience design.
Urban wetlands are acoustic hotspots where vegetation structure, hydrological dynamics, and anthropogenic noise interact, yet multi-season assessments of how vegetation influences avian soundscapes are limited. This study explored bird soundscape dynamics across forest, open forest grassland, and meadow habitats in Nanjing Xinjizhou National Wetland Park, eastern China, using passive acoustic monitoring during spring and autumn 2023. Twelve sampling points (four per vegetation type) were established, and six acoustic indices were calculated, including the Acoustic Complexity Index (ACI), Acoustic Diversity Index (ADI), Acoustic Evenness Index (AEI), Bioacoustic Index (BIO), Normalized Difference Soundscape Index (NDSI), and Acoustic Entropy Index (H). were calculated from 48-h recordings each season. Random forest models and redundancy analysis assessed the relationships between acoustic indices, fine-scale vegetation parameters (e.g., crown width, tree height, species richness), and anthropogenic factors (e.g., distance to roads/trails, surface hardness). Vegetation structure, particularly crown width, was the primary driver of avian acoustic diversity, with broad-crowned forests consistently exhibiting the highest acoustic complexity. In spring, anthropogenic factors such as trail and road proximity dominated soundscape variation, suppressing biological sounds. In autumn, with reduced human presence, vegetation structure emerged as the dominant factor, while bioacoustic activity remained elevated despite reduced peaks in acoustic complexity. Proximity to roads increased low-frequency (1-2 kHz) noise and suppressed mid-frequency (4-8 kHz) bird vocalizations, but trees with crown widths ≥4 m maintained higher acoustic diversity even near disturbance sources. This study demonstrates that vegetation structure mediates both resource availability and sound propagation, buffering the effects of anthropogenic disturbance in frequency-specific ways. Multi-season sampling is crucial for understanding the dynamic interplay between vegetation phenology and human activity that shapes urban wetland soundscapes.
Coral restoration is recognised as a critical tool to mitigate pantropical degradation of reef ecosystems. Robust monitoring of restoration progress is crucial for projects to evaluate their success, improve practice, and share knowledge. However, traditional visual surveys often fail to capture the full impact of coral restoration on reef function. Therefore, we employed Passive Acoustic Monitoring (PAM) to assess whether the soundscape of a coral restoration site in the Seychelles differs from adjacent healthy and degraded reference reefs. We applied two methods of soundscape analysis: manual detection of unidentified fish sounds; and machine learning-based Uniform Manifold Approximation and Projection analysis. Results were approach-specific: the manual approach highlighted similarities in fish calls between the restoration site and the healthy reference reef, while the machine learning approach extracted broader soundscape patterns, clustering the restoration site alongside the degraded reference reef. Although this is a single-site study, these findings suggest that a) coral restoration alters reef soundscapes, though recovery time may be taxon-specific, and b) multiple metrics are needed to bridge single-taxon and broad soundscape scales. This study contributes to the evolving field of soundscape ecology in coral reef ecosystems, highlighting the utility of PAM in monitoring changes to reef function through coral restoration.
This study focuses on the soundscape and spatial structure of urban parks. Four representative parks in Fuzhou City were selected as case studies. Data was collected through a combination of questionnaire surveys, sound level measurements, and on-site recordings. Deep learning code was used to implement audio automatic classification, image semantic segmentation, and depth estimation processes. Based on this, a multi-dimensional spatial analysis indicator system was constructed, and a subjective and objective soundscape evaluation system was established simultaneously. Using methods such as correlation analysis, stepwise regression, cluster analysis, and geographically weighted regression, the study progressively revealed significant differences in the composition of soundscapes and their influencing factors between park boundaries and internal spaces. The results indicate that the soundscapes of boundary spaces are more significantly influenced by urban traffic, facilities, and layout, while internal spaces are more dependent on vegetation structure and visual perception elements. Soundscape characteristics exhibit obvious scale heterogeneity and structural dependency across different spatial types. This provides theoretical basis and data support for the management and optimization of acoustic environments in urban landscape spaces.
Urban zoos are important but complex artificial ecosystems that integrate wildlife conservation with public education. Their soundscapes, including anthrophony, biophony, and geophony, show significant spatiotemporal dynamics. Persistent fluctuations could contribute to chronic stress in captive animals and human visitors, impairing welfare and conservation outcomes. Existing research focuses on static noise levels, neglecting spatiotemporal dynamics in zoo soundscapes. To address this gap, we deployed passive acoustic monitoring (PAM) with 20 acoustic recorders at Zhengzhou Zoo across seven functional zones between weekdays and weekends during summer in 2024. We analyzed six acoustic indices: Acoustic Complexity Index (ACI), Acoustic Diversity Index (ADI), Acoustic Evenness Index (AEI), Bioacoustic Index (BIO), Normalized Difference Soundscape Index (NDSI) and A-weighted sound pressure level (SPL(dBA)). These were combined with non-metric multidimensional scaling, generalized additive models, and kernel principal component analysis. Quantitatively, we found that SPL (dBA) increased by up to 10 dB on weekends compared to weekdays, while ACI rose by approximately 20%. A very strong negative correlation was observed between ADI and AEI, indicating an inverse dynamic between acoustic diversity and evenness. Building on these results, the analysis revealed distinct diel patterns, with biophony dominating during dawn and dusk periods, while anthrophony peaked during day hours. The weekend effect was significantly identified with these elevated SPL (dBA) and ACI, alongside reduced acoustic stability. Significant acoustic divergence was observed among functional zones, with elevated SPL (dBA) and ACI in High-traffic Zone but with reduced BIO in others. The results indicate that biological rhythms, human activities, and environmental structures collectively shape zoo soundscapes, and PAM and acoustic indices can provide a robust scientific basis for acoustic-based animal welfare and visitor management in zoos.
Anthropogenic noise is increasingly recognized as a stressor to marine animals, but is rarely considered as a pollutant in freshwater ecosystems. We therefore characterized underwater soundscapes in three major European rivers (Rhine, Elbe, Gironde). We evaluated how natural soundscapes are shaped by biotic sounds (biophony) and river hydro-geomorphology (geophony). Furthermore, we assessed level and duration of boat noise to provide insight into disturbance and masking potential. We (1) characterized biophony in 24-h recordings; (2) assessed relationships between hydro-geomorphological features and the soundscape using drifting hydrophone recordings (geophony); (3) quantified boat noise in 24-h recordings; (4) evaluated masking potential through sound spectrum comparisons between natural sounds and boat noise; and (5) assessed the value of Automatic Identification System (AIS)-based shipping density data to predict noise impact from commercial vessels in large rivers. River soundscapes contained biophony from diverse taxa. Water velocity and sediment hardness explained a significant proportion of the variation in background sound levels at frequencies above 350 Hz, and sound levels sharply increased above 1.4 m/s. In the presence of boat noise, most natural sounds have high potential to be masked. Boat noise occupied 42-86% of recording time in the Rhine, 2-38% in the Elbe, and 0-20% in the Gironde. We found a significant relationship between AIS boat density and recorded and extrapolated boat noise along each river. We conclude that: (a) river soundscapes reflect information on nearby physical river features and biota, providing environmental cues to aquatic animals, and (b) that boat noise is widespread and persisting for long periods, potentially disturbing aquatic fauna and masking natural auditory cues in large rivers.
The proliferation of smart technology has led to the diversification and randomization of indoor sound sources. This necessitates a more nuanced consideration of user subjective experiences in indoor soundscape design. Consequently, identifying the perceptual dimensions of smart home soundscapes has become a critical issue in indoor sound environment design. Accordingly, this study aimed to identify the perceptual dimensions of smart home soundscapes, using a mixed-methods approach that combined qualitative and quantitative techniques. First, perceptual indicators were extracted based on grounded theory. Subsequently, virtual reality (VR) technology was used to simulate 12 different sound sources within three typical scenarios (Rest/ Entertainment/ Work). Quantitative perceptual data were collected from 120 participants in laboratory settings. Finally, factor analysis was applied to extract the perceptual dimensions of both the sound sources and sound environment. The results indicated the following: (1) Interview data culminated in 29 evaluation indicators for sound sources and 21 indicators for the sound environment. (2) The perceptual dimensions of the sound sources included comfort, informativeness, pleasantness, clarity, and redundancy. (3) The overall perception of the sound environment can be summarized as comfort and recognisability. Furthermore, the study discussed perceptual differences across various sound sources and scenario types through an analysis of variance (ANOVA) and principal component distributions. The conclusions provide a theoretical framework for indoor soundscape design and offer design implications for the acoustic optimisation of smart home products.
Acoustic indices are popular tools for rapid biodiversity assessment using passive acoustic monitoring recordings, yet anthropogenic sounds in human activity areas compromise their robustness. In this paper, we focus on the typical urban-rural soundscape, where anthropogenic noise mainly originates from a narrow angular sector far from the monitoring device. We propose a denoising preprocessing algorithm with two microphone sensors for the robust application of existing acoustic indices. Our algorithm first develops an adaptive multi-tap null-steering beamformer based on a back-to-back first-order differential microphone array, which increases the system degrees of freedom to enhance the broadband interference cancellation capability. Building on this, a parallel bank of mutually orthogonal null-steering beamformers is proposed, each forming deep nulls toward directional interference-concentrated bands and generating diverse responses to the target signal. Finally, a signal compensation mechanism is applied to the beamformers' outputs, mitigating the signal self-cancellation effects from these unconstrained adaptive beamformers prior to index calculation. The proposed preprocessing method is evaluated using the frequency-dependent acoustic diversity index as a representative of acoustic indices. Experiment results on both simulation and real-world recordings show that the proposed method generates high-fidelity acoustic information for subsequent acoustic index calculation over a much wider signal-to-interference-plus-noise ratio (SINR) range in urban-rural soundscapes characterized by directional anthropogenic interference.
Soundscape monitoring assesses biodiversity by analyzing environmental acoustic signals, but overlapping sound sources in complex environments limit the performance of traditional methods. We propose an unsupervised blind source separation algorithm using nonnegative matrix factorization (NMF) and a two-stage coarse-to-fine clustering strategy. First, NMF decomposes the mixed spectrogram into spectral bases and temporal activations. In the clustering stage, coarse clustering is first performed via a second NMF with sparsity constraints using the spectral bases, temporal activations, or their derived features. Subsequently, fine clustering is performed using hierarchical clustering-guided K-means, which leverages complementary feature dimensions to refine the initial groups. Performance was evaluated on both simulated data and real-world recordings using separation quality metrics, detection metrics, and a composite score. Robustness was further examined under different mixture complexities. Results demonstrate that the proposed method achieves superior separation performance compared to one-stage clustering on both simulated and real-world data, particularly in successfully recovering a greater number of source components. This work provides a practical approach for fine-grained source separation in complex soundscapes and supports quantitative ecoacoustic analysis.
This paper presents a dataset of real-world Ghanaian environmental soundscapes intended to support machine-listening research and sound-event classification in low-resource contexts. The collection contains 22,193 uncompressed 44.1 kHz/16-bit WAV recordings, captured using mobile devices across diverse environments, including urban spaces, educational institutions, marketplaces, transport hubs, and human non-verbal acoustic settings. Recordings were obtained under natural field conditions to retain authentic background noise, reverberation, and overlapping sound events. Each file is accompanied by structured metadata specifying category, class, subclass, location, and context, and all annotations have been manually verified to ensure label consistency and quality. The dataset addresses a critical geographic gap in global audio resources and provides culturally and acoustically representative material from Sub-Saharan Africa. It offers strong potential for applications in environmental monitoring, sound event detection, accessibility tools, hearing-assistive technologies, and broader audio-based AI systems.
This exploratory study evaluates audio-rendering method and listening position in-cabin music listening environments under controlled audiovisual presentation. Twenty-two participants experienced two, 6 min music excerpts under five scenarios combining reference stereo playback, measured impulse-response-based seat-specific auralization, and surround-enhanced Dolby 5.1 reproduction. Perceptual ratings consistently differentiated the scenarios. Surround-enhanced conditions generally improved spatial impression, envelopment, and presence/realism relative to the standard auralized conditions, while front and rear listening positions produced different clarity and reverberance patterns consistent with measured impulse-response differences. Heart rate variability showed a significant omnibus effect for the low-frequency/high-frequency ratio in the orchestra excerpt, although corrected pairwise differences were not robust; electroencephalography alpha power showed condition-dependent regional differences in temporal, parietal, and occipital areas. Correlation analyses linked level and psychoacoustic descriptors, including sharpness and dynamic level range, to perceptual attributes, indoor soundscape expressions, and overall impression. The study contributes a reproducible measurement-based workflow for seat-aware in-cabin music soundscape evaluation and suggests that passenger audio tuning should consider rendering method and listening position as coupled design variables.
Soundscapes reflect interacting biological, physical, and sensor-driven processes; thus, passive acoustic monitoring (PAM) can provide a wealth of unique, multifaceted ecological information. Using coral reefs as an example, we outline how mechanistic, integrative interpretation is essential for reliable ecological inference and for realising PAM's growing potential in ecosystem monitoring.
The human ability to hear animal vocalisations in natural settings was studied by asking naive participants to detect vocalisations in 11 520 samples from a large database of soundscapes varying in terms of habitat (latitude), moment of the day, and precipitation period. Results show that agreement was moderate/good across participants, and the number of vocalisation detections varied systematically as a function of the three ecological factors: Vocalisations were more often detected in the most equatorial habitats, at sunrise and sunset, and for the highest precipitation period. These results are consistent with the latitudinal gradient of biodiversity and diel and seasonal cycles of animal vocal activity. Analysis of modulation power spectra for sounds categorised as containing vocalisations indicates that listeners may base their decisions upon a variety of spectro-temporal modulation cues that are mostly influenced by the openness of the habitat (savannah and desert versus forests). This finding may reflect either adaptation of animal vocal production to the specific sound-propagation characteristics of their native environment, and/or the filtering and distortion effects caused by sound-propagation within natural habitats. This study reveals important ecological constraints on sensory mechanisms involved in detection of vocalisations and provides modulation templates involved in this process for further research.
Ecoacoustic indices have become widely used tools for monitoring and characterizing soundscapes. Although they have proven useful for relating acoustic measurements to ecological patterns, their conceptual and methodological foundations remain debated. Here, this Letter identifies five recurring limitations, ranging from theoretical disconnects to methodological shortcomings, that undermine their interpretability, reproducibility, and ecological relevance. The Letter concludes by outlining a possible roadmap to address these limitations, including the adoption of auditory-inspired representations, the standardization of computational procedures, validation across contexts, and the use of more explainable modeling approaches.
Open-plan offices are designed to foster collaboration but often face challenges related to noise and acoustic comfort, which can affect employee well-being and productivity. The soundscape concept offers a holistic approach to assessing and improving these environments, yet existing methods often fall short of capturing the complexity of open-plan offices. This study addresses this gap by developing a structured questionnaire tailored for open-plan offices, integrating acoustic and non-acoustic factors. Expert focus group discussions were conducted to identify and expand upon key factors influencing soundscape assessments, building on insights from prior research. Thematic analysis revealed critical considerations, including individual characteristics, spatial dynamics, sound environment perception, office acoustic metrics, noise control, work performance, and psychosocial conditions. To effectively incorporate these elements, the study recommends adapting existing soundscape frameworks to the specific context of open-plan offices. The proposed approach prioritises brevity, logical structure, and user-friendly language to enhance participant engagement and data quality, enabling practical and insightful assessments centred on user experience.
Nocturnal environments and their ecology remain noticeably under-represented in the scientific literature, despite their ecological importance, largely due to the practical challenges of sampling nighttime ecology. Passive acoustic monitoring provides a cost-effective, scalable tool for extracting ecological insights from continuous recordings, using acoustic indices. This study assessed whether a suite of acoustic indices can capture the diversity of nighttime calls (i.e., sonotype richness used here as a proxy for biodiversity) in a terrestrial ecosystem. Our main findings supported an interaction effect of indices (acoustic activity (ACT), acoustic evenness (AEI), spectral entropy (Hf), soundscape saturation (Sm)) correlating best with variation in sonotype richness. This result was further supported by habitat-dissimilarity analyses based on manually tagged insect sonotype richness compared to index values showing significant similarities. Although the methodological framework used in this study is adaptable to other environments, index performance is unlikely to be directly transferable due to differences in vocal assemblages and background noise conditions. Overall, the study provides a useful procedure to track patterns in nighttime ecology and support the evaluation of the state of nighttime ecology.
The widely held assumption that closing eyes enhances auditory sensitivity has been supported by auditory attention experiments. However, the visual effects on auditory thresholds of detecting target sounds masked by noise remain unexplored. We investigated the participants' detection thresholds (n = 25) of target sounds (canoe paddle, drum, lark chirping, train, and keyboard) masked by 70 dB(A) pink noise under four visual conditions (eyes closed, eyes open with blank board, static visual stimulation, and dynamic visual stimulation). Taking blank visual stimulation as the baseline, eye closure elevated detection thresholds by 1.32 dB on average, whereas dynamic and static relevant visual stimulation lowered them by 2.98 and 1.60 dB, respectively, contrary to conventional belief. Electroencephalogram recordings (n = 27) demonstrated avalanche critical index reduction of 22.3%-45.2% across five auditory stimuli under eye closure compared with blank stimulation, revealing that non-visual states preferentially stabilize neural dynamics near critical states. We propose a unified auditory-cortical framework based on the brain dynamics theory to explain both the enhanced auditory target detection during visual engagement in noisy environments and optimized auditory segregation via visual disengagement in quiet settings, advancing our understanding of visual effects on auditory perception in complex noisy soundscapes.
Environmental sounds are rich and varied, and hence, characterizing them efficiently to track their evolution over time or contrast them when necessary can be a difficult endeavor. Here, we suggest that the multiresolution "cortical" representation inspired by auditory neurophysiological and psychoacoustical studies provides an effective means to accomplish these goals. It does so by recapitulating the analysis of sound at various stages of the auditory pathway, achieving at the end a perceptually relevant representation of the soundscape surrounding us to enjoy it, to preserve its health, and to avoid its degradation.
Wildfires significantly impact biodiversity, yet their effects on acoustic communities and soundscapes more generally are still not fully comprehended. This study employs passive acoustic monitoring (PAM) and ecoacoustics tools to assess the impact of human-caused wildfires on the anuran communities and the soundscape composition in the premontane strata of the Yungas Andean forests of Argentina. We deployed nine automated recording units across burned, semi-burned, and non-burned forest sites. We assessed anuran species richness by manual annotations from the recordings and analyzed the soundscape diversity and composition using Operational Sound Units and Hill-based soundscape diversity indices. Non-burned forest sites exhibited significantly higher anuran species richness compared to fire-affected sites. In addition, soundscape diversity was reduced in fire-affected sites, with non-burned forests retaining high-frequency biophony, unlike burned forests dominated by low-frequency sounds. Principal coordinate analysis revealed differences in soundscape composition among acoustic communities, with burned and semi-burned sites clustering separately from non-burned sites. Daily sound patterns showed dramatic changes in burned areas, indicating disrupted ecological acoustic niches. Our findings show that wildfires significantly alter both the anuran diversity and soundscapes composition, particularly affecting habitat-specialist species like treefrogs. Ecoacoustic tools effectively captured imminent post-fire soundscape changes, highlighting their utility for monitoring impacts on biodiversity. These results underscore the need for integrated wildfire prevention programmes aiming to conserve acoustic communities and soundscapes in threatened ecosystems. Long-term PAM is recommended to track post-fire biodiversity recovery and to evaluate conservation actions in the Yungas forests and other fire-prone landscapes.