Clustering outdoor soundscapes using fuzzy ants

A classification algorithm for environmental sound recordings or "soundscapes" is outlined. An ant clustering approach is proposed, in which the behavior of the ants is governed by fuzzy rules. These rules are optimized by a genetic algorithm specially designed in order to achieve the optimal set of homogeneous clusters. Soundscape similarity is expressed as fuzzy resemblance of the shape of the sound pressure level histogram, the frequency spectrum and the spectrum of temporal fluctuations. These represent the loudness, the spectral and the temporal content of the soundscapes. Compared to traditional clustering methods, the advantages of this approach are that no a priori information is needed, such as the desired number of clusters, and that a flexible set of soundscape measures can be used. The clustering algorithm was applied to a set of 1116 acoustic measurements in 16 urban parks of Stockholm. The resulting clusters were validated against visitor's perceptual measurements of soundscape quality

A new methodology for modelling urban soundscapes: a psychometric revisitation of the current standard and a Bayesian approach for individual response prediction

Measuring how the urban sound environment is perceived by public space users, which is usually referred as urban soundscape, is a research field of particular in terest for a broad and multidisciplinary scientific community besides private and public agencies. The need for a tool to quantify soundscapes would provide much support to urban planning and design, so to public healthcare. Soundscape liter ature still does not show a unique strategy for addressing this topic. Soundscape definition, data collection, and analysis tools have been recently standardised and published in three respective ISO (International Organisation for Standardization) items. In particular, the third item of the ISO series defines the calculation of the soundscape experience of public space users by means of multiple Likert scales. In this thesis, with regards to the third item of the soundscape ISO series, the soundscape data analysis standard method is questioned and a correction paradigm is proposed. This thesis questiones the assumption of a point-wise superimposition match across the Likert scales used during the soundscape assessment task. In order to do that, the thesis presents a new method which introduces correction values, or metric, for adjusting the scales in accordance to the results of common scaling behaviours found across the investigated locations. In order to validate the results, the outcome of the new metric is used as tar get to predict the individual experience of soundscapes from the participants. In comparison to the current ISO output, the new correction values reveal to achievea better predictability in both linear and non-linear modelling by increasing the ac-curacy of prediction of individual responses up to 52.6% (8.3% higher than theaccuracy obtained with the standard method).Finally, the new metric is used to validate the collection of data samples acrossseveral locations on individual questionnaires responses. Models are trained, in aiterative way, on all the locations except the one used during the validation. Thisprocedure provides a strong validating framework for predicting individual subjectassessments belonging to locations totally unseen during the model training. The results show that the combination of the new metrics with the proposed modelling structure achieves good performance on individual responses across the dataset withan average accuracy above 54%. A new index for measuring the soundscape is fi-nally introduced based on the percentage of people agreeing on soundscape pleas-antness calculated from the new proposed metric and performing a r-squared valueequals to 0.87.The framework introduced is limited by cultural and linguistic factors. Indeed,different corrected metric space are expected to be found when data is collected from different countries or urban context. The current values found in this thesis areso expected to be valid in large British cities and eventually in international hub andcapital cities. In these scenarios the corrected metric would provide a more realisticand direction-invariant representation of how the urban soundscape is perceived compared to the current ISO tool, showing that some components in the circumplex model are perceived softer or stronger according to the dimension. Future research will need to understand better the limitations of this new ramework and to extendand compare it towards different urban, cultural, and linguistic contexts

Methodology for ecosystem change assessing using ecoacoustics analysis

RESUMEN: La ecoacústica se ha convertido en un área de creciente interés para el monitoreo de ecosistemas. Entre las principales ventajas que presenta sobre las técnicas tradicionales se encuentran su bajo costo, poca afectación al entorno y simplicidad; además de que la distribución de varias grabadoras hace posible la recolección de más información. Sin embargo, para estudios de largo plazo, la cantidad de datos hace que la inspección manual de las grabaciones sea una tarea tediosa y por consiguiente el análisis sea limitado. Como alternativa a la inspección manual, una serie de índices han sido propuestos para resumir la información acústica de las grabaciones. No obstante, estos índices han sido aplicados principalmente a estudios de biodiversidad y su relación con el estado del ecosistema no es claro aún. En este trabajo se confió en la robustez del ANOVA frente a datos que no se distribuyen normalmente para proponer una metodología de selección de los mejores índices o descriptores acústicos para una aplicación específica y usarlos para modelar los patrones del paisaje acústico del ecosistema con modelos ocultos de Markov y emisiones por mezclas Gaussianas (GMMHMM). Además, el conjunto de descriptores que entran al modelo incluye por defecto un indicador de biodiversidad para cada banda de 1kHz. Esta metodología fue aplicada a dos casos colombianos con tipos de ecosistema definidos. En el primer caso, una serie de grabaciones de bosque, rastrojo y pastizal fueron colectados por más de un año en el este de Antioquia. La segunda aplicación buscaba encontrar patrones de paisaje acústico de las transformaciones de bosque seco en dos regiones del caribe colombiano. El modelo identificó seis y tres patrones acústicos para la primera y segunda base de datos respectivamente. En la primera aplicación, se encontraron sonidos continuos, alta intensidad biofónica y ocupación de varias bandas en los patrones asociados a bosque, mientras que en los rastrojos se presentó más entropía, que se relaciona con alta presencia geofónica, lo que limita la actividad biofónica. Finalmente los paisajes acústicos de pastizal alternaron entre periodos de alta geofonía y alta complejidad frecuencial, haciéndolo un ecosistema intermedio en el sentido acústico. La adaptación del modelo para clasificación resultó en la identificación del 81% de las muestras de bosque, 96,6 % de las muestras de rastrojo y 51,2 % de las muestras de pastizal. Los resultados de clasificación para la segunda aplicación no fueron altos, con 68% para las muestras de baja transformación, 58,9% para la transformación media y 31,8% para la transformación alta. No obstante, las matrices de confusión indicaron que las muestras de entrenamiento no fueron suficientes, y que debería proporcionarse mayor muestreo para obtener mejores resultados. Dado que GMMHMM es un modelo secuencial, también presentó la configuración temporal de los patrones acústicos dadas sus probabilidades de transición. Esta característica nos permitió destacar la importancia de la conservación, cuando encontramos que los estados más estables e inaccesibles fueron asociados a los ecosistemas más diversos acústicamente.ABSTRACT: Ecoacoustics has become a field of growing interest for ecosystem monitoring. Its main advantages over traditional methods include cost effectiveness, non-invasiveness and simplicity; besides the distribution of many recorder units makes possible the recollection of more information. However, for long term studies, the quantity of collected data makes the manual inspection of recordings a cumbersome task, leading to reduced analysis. As an alternative to manual inspection, a series of indices have been proposed to summarize the acoustical information in recordings. Nonetheless, these indices have been applied mainly to biodiversity studies and their connection to ecosystem state is still not clear. In this work we trusted ANOVA robustness for non-normal data for proposing a methodology that selected the best acoustical indices or features for a specific application and used them to model the ecosystem soundscape patterns with hidden Markov models and Gaussian mixture emissions (GMMHMM). Additionally, the set of input features included by default a biodiversity indicator per 1kHz band. This methodology was applied to two Colombian cases with defined ecosystem types. In the first case, a series of forest, stubble and pasture recordings were collected for over a year in the east of Antioquia. The second application aimed to find the soundscape patterns of dry forests transformations in two regions of the Colombian Caribbean. The model identified six and three soundscape patterns for the first and second dataset respectively. In the first application, continuous sounds, high biophonic intensity and multiple occupied frequency bands were found in the patterns associated to forest sites; on the other hand, stubble sites presented more general entropy, which we related to high geophonic presence, preventing biophonic activity. Lastly, pasture soundscapes alternated between periods of high geophony and high frequency complexity, making it an intermediate ecosystem in the acoustical sense. The adaptation of the model for classification resulted in the identification of 81% of the forest samples, 96.6% of the stubble samples and 51.2% of the pasture samples. The classification results for the second application were not as high, with 68% for the low transformation samples, 58.8% for the medium transformation and 31.8% for the high transformation. Nonetheless, the confusion matrices indicated that the training samples were not enough, and more sampling should be provided for attaining better results. Given that GMMHMM is a sequential model, it also presented the temporal configuration of the acoustical patterns by their transition probabilities. This feature allowed us to emphasize the importance of conservation, when we found that the most stable and inaccessible states were associated to the most acoustically diverse ecosystems

Exploring Animal Behavior Through Sound: Volume 1

This open-access book empowers its readers to explore the acoustic world of animals. By listening to the sounds of nature, we can study animal behavior, distribution, and demographics; their habitat characteristics and needs; and the effects of noise. Sound recording is an efficient and affordable tool, independent of daylight and weather; and recorders may be left in place for many months at a time, continuously collecting data on animals and their environment. This book builds the skills and knowledge necessary to collect and interpret acoustic data from terrestrial and marine environments. Beginning with a history of sound recording, the chapters provide an overview of off-the-shelf recording equipment and analysis tools (including automated signal detectors and statistical methods); audiometric methods; acoustic terminology, quantities, and units; sound propagation in air and under water; soundscapes of terrestrial and marine habitats; animal acoustic and vibrational communication; echolocation; and the effects of noise. This book will be useful to students and researchers of animal ecology who wish to add acoustics to their toolbox, as well as to environmental managers in industry and government

Exploring Animal Behavior Through Sound: Volume 1

This open-access book empowers its readers to explore the acoustic world of animals. By listening to the sounds of nature, we can study animal behavior, distribution, and demographics; their habitat characteristics and needs; and the effects of noise. Sound recording is an efficient and affordable tool, independent of daylight and weather; and recorders may be left in place for many months at a time, continuously collecting data on animals and their environment. This book builds the skills and knowledge necessary to collect and interpret acoustic data from terrestrial and marine environments. Beginning with a history of sound recording, the chapters provide an overview of off-the-shelf recording equipment and analysis tools (including automated signal detectors and statistical methods); audiometric methods; acoustic terminology, quantities, and units; sound propagation in air and under water; soundscapes of terrestrial and marine habitats; animal acoustic and vibrational communication; echolocation; and the effects of noise. This book will be useful to students and researchers of animal ecology who wish to add acoustics to their toolbox, as well as to environmental managers in industry and government

Woodland soundscapes: Investigating new methods for monitoring landscapes

Biodiversity is an important provider of ecosystem services. There is a sense of urgency running through the scientific community regarding its protection and conservation. This urgency is fuelled by a wealth of research into the effects of habitat destruction, intensive agriculture, destructive industries (such as mining and oil exploration) and the insidious threat of climate change. It might reasonably be suggested that the biodiversity crisis we are facing today is in large part due to a lack of regulation around human-activities with regard to biodiversity impacts. In order to impose regulations, protecting biodiversity has been incentivised through various governmental and non-profit private-sector certification initiatives that aim to minimise the negative impacts that industry can have on the environment. Agri-environment schemes are largely governmental initiatives that aim to enhance the biodiversity and societal values of farmland. Timber certification initiatives, such as the Forest Stewardship Council, promote woodland management that takes into account the economic, environmental and social aspects of forestry with equal measure. Protection and enhancement of biodiversity is integral to achieving the environmental aims of certification. However, several studies have highlighted that many schemes (notably agri-environment schemes and some timber certification schemes) ultimately fall short of their projected targets, which is often due to a lack of suitable monitoring with regard to biodiversity. This is unsurprising since biodiversity monitoring is not a straightforward process. Many considerations need to be made when choosing suitable indicators of ecosystem health such as whether to measure species diversity or functional diversity. But perhaps one of the biggest issues is the ability of landowners and managers to contribute to efficient, objective, standardised data collection. Acoustic monitoring offers a means of producing unbiased data that can be analysed objectively and stored indefinitely. With significant advances in hardware and software technologies, the proliferation of acoustic monitoring is evident in the scientific literature.The field of soundscape ecology was in many respects borne out of these technological advances. It has since been usurped by the newer field of ecoacoustics (I use these two terms interchangeably throughout this thesis). Ecoacoustics offers a range of soundscape analytical techniques that aim to understand the spectral and temporal composition of the soundscape. As such a number of acoustic indices can be used to measure different facets of acoustic diversity. This study offers an overview of the current literature in bioacoustics and ecoacoustics. It applies several of these indices to studying the soundscape of Forest Stewardship Council certified plantation forests in the UK. Specifically it investigates the soundscape in relation to habitat and landscape metrics and explores temporal variation in acoustic activity. It offers insights into the relationship between man-made/machine noise (technophony) and biological sounds (biophony) and suggests future directions for research and large-scale monitoring of habitats. Finally it provides a set of instructions on how to build an automated recording unit using readily available parts and provides links to necessary software and guidance on types of hardware available. The key findings indicate that the use of acoustic indices for monitoring landscapes could be a useful tool. Clear relationships were observed between forest structure and stand age, and vegetation structure, with acoustic diversity in Thetford forest over two consecutive years. Although these relationships were not clear in Bedgebury forest, the effects of landscape structure were statistically significant, particularly when using automated recording units. Road proximity had a strong influence on the soundscape in all study sites. And the use of ecoacoustic methods to explore this offers an insight into a new means of investigating the impact of roads on acoustic biodiversity. The development of a low-cost automated recording unit is a significant contribution to the field of soundscape ecology in terms of encouraging participation by the non-governmental organisation (NGO) sector. Likewise, the use of a handheld recording unit and the application of traditional ecological survey methods provide evidence that soundscape/ecoacoustic studies that yield interesting, informative and biologically meaningful results can be done on a relatively low budget. As such this thesis offers a significant contribution to the field of soundscape ecology in terms of both data and logistics. It may be particularly relevant to researchers on a limited budget and/or the NGO and citizen science sector