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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
The sounds produced by geophonic, biophonic and technophonic sources are relevant to the function of natural and human modified ecosystems. Passive recording is one of the most non-invasive technologies as its use avoids human intrusion during acoustic surveys and facilitates the accumulation of huge amounts of acoustical data. For the first time, this book collates and reviews the science behind ecoaucostics; illustrating the principles, methods and applications of this exciting new field. Topics covered in this comprehensive volume include; * the assessment of biodiversity based on sounds emanating from a variety of environments * the best technologies and methods necessary to investigate environmental sounds * implications for climate change and urban systems * the relationship between landscape ecology and ecoacoustics * the conservation of soundscapes and the social value of ecoacoustics * areas of potential future research. An invaluable resource for scholars, researchers and students, Ecoacoustics: The Ecological Role of Sounds provides an unrivalled set of ideas, tools and references based on the current state of the field.
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Table of Contents
Cover
Title Page
Copyright
List of Contributors
Preface
Chapter 1: Ecoacoustics: A New Science
1.1 Ecoacoustics as a New Science
1.2 Characteristics of a Sound
1.3 Sound and its Importance
1.4 Ecoacoustics and Digital Sensors
1.5 Ecoacoustics Attributes
1.6 Ecoacoustics and Ecosystem Management
1.7 Quantification of a Sound
1.8 Archiving Ecoacoustics Recordings
1.9 Ecological Forecasting
References
Chapter 2: The Duality of Sounds: Ambient and Communication
2.1 Introduction
2.2 Vegetation and Ecoacoustics
2.3 Acoustic Resources, Umwelten, and Eco-fields
2.4 Sounds as Biological Codes
2.5 Sound as a Compass for Navigation
2.6 Geophonies from Sacred Sites – How to Incorporate Archeoacoustics into Ecoacoustics
References
Chapter 3: The Role of Sound in Terrestrial Ecosystems: Three Case Examples from Michigan, USA
3.1 Introduction
3.2 C1 Visualization of the Soundscape at Ted Black Woods, Okemos, Michigan during May 2016
3.4 C3 Disturbance in Terrestrial Systems: Tree Harvest Impacts on the Soundscape
References
Chapter 4: The Role of Sound in the Aquatic Environment
4.1 Overview on Underwater Sound Propagation
4.2 Sound Emissions and their Ecological Role in Marine Vertebrates and Invertebrates
4.3 Impacts of Anthropogenic Noise in Aquatic Environments
References
Chapter 5: The Acoustic Chorus and its Ecological Significance
5.1 Introduction
5.2 Time of Chorus
5.3 The Chorus Hypothesis
5.4 Choruses in Birds
5.5 Choruses in Amphibians
5.6 Choruses in the Marine Environment
5.7 Conclusions and Discussion
References
Chapter 6: The Ecological Effects of Noise on Species and Communities
6.1 Introduction
6.2 The Nature of Noise
6.3 Natural Sources of Noise
6.4 Anthropogenic Sources of Noise
6.5 Effects of Noise on the Animal World
6.6 How Animals Neutralize the Effect of Noise
6.7 Noise in Marine and Freshwater Systems
6.8 Conclusions
References
Chapter 7: Biodiversity Assessment in Temperate Biomes using Ecoacoustics
7.1 Introduction
7.2 Sound as Proxy for Biodiversity
7.3 Methods and Application of Ecoacoustics
7.4 Acoustic Communities as a Proxy for Biodiversity
7.5 Problems and Open Questions
7.6 Ecoacoustic Events: Concepts and Procedures
7.7 Conclusion
References
Chapter 8: Biodiversity Assessment in Tropical Biomes using Ecoacoustics: Linking Soundscape to Forest Structure in a Human-dominated Tropical Dry Forest in Southern Madagascar
8.1 Introduction
8.2 Methods
8.3 Results
8.4 Discussion
References
Chapter 9: Biodiversity Assessment and Environmental Monitoring in Freshwater and Marine Biomes using Ecoacoustics
9.1 Introduction
9.2 Freshwater Habitats
9.3 Marine Neritic Habitats
9.4 Marine Oceanic Habitats
9.5 Summary and Future Directions
References
Chapter 10: Integrating Biophony into Biodiversity Measurement and Assessment
10.1 Introduction
10.2 Biological Information in the Soundscape
10.3 Ecoacoustics in Biodiversity Assessment
10.4 Conclusion
References
Chapter 11: Landscape Patterns and Soundscape Processes
11.1 An Introduction to Landscape Ecology (Theories and Applications)
11.2 Relationship Between Landscape Ecology and Soundscape Ecology: A Semantic Approach
11.3 Acoustic Community and Landscape Mosaics
11.4 Ecoacoustics in a Changing Landscape
11.5 Conclusion
References
Chapter 12: Connecting Soundscapes to Landscapes: Modeling the Spatial Distribution of Sound
12.1 Introduction
12.2 Conceptualizing Soundscapes in Space and Time
12.3 Capturing Soundscapes in Space and Time
12.4 Sound Metrics and Interpreting Nature
12.5 A Soundscape Metric for Modeling
12.6 Discriminating the Components of a Soundscape
12.7 Generating a Predictive Soundscape Model
12.8 Conclusion
References
Chapter 13: Soil Acoustics
13.1 Introduction
13.2 Soil Insect Acoustics
13.3 Compost Activating Agent Acoustics
13.4 Soil Aggregate Slaking Acoustics
13.5 Conclusion
References
Chapter 14: Fundamentals of Soundscape Conservation
14.1 Introduction
14.2 Nature Sounds in Science and Education
14.3 The Role of Sound Libraries
14.4 Noise Pollution, the Acoustic Habitat, and the Biology of Disturbance
14.5 Soundscapes, Nature Conservation, and Public Awareness
14.6 Marine Soundscapes
14.7 Conclusion
References
Chapter 15: Urban Acoustics: Heartbeat of Lansing, Michigan, USA
15.1 Introduction
15.2 Objectives
15.3 Methods
15.4 Results
15.5 Discussion and conclusions
References
Chapter 16: Analytical Methods in Ecoacoustics
16.1 Introduction
16.2 Components of an Acoustic Recording
16.3 Visualization of an Acoustic Recording
16.4 Processing Multiple Recordings
16.5 Analyzing Acoustic Time Series
16.6 Time Series of Acoustic Indices
16.7 Searching and Symbolic Methods
16.8 Visualization and Navigation of Long-Duration Recordings
16.9 Spectrogram Pyramids
16.10 New Approaches to Analysis
16.11 Web Platforms for the Visualization of Environmental Audio
References
Chapter 17: Ecoacoustics and its Expression through the Voice of the Arts: An Essay
17.1 Introduction
17.2 Immersive Art as a Science Dissemination Tool
17.3 Examples of Ecoacoustic Works by Bernie Krause
17.4 Examples of Ecoacoustics Works by David Monacchi
17.5 Conclusion
References
Chapter 18: Ecoacoustics Challenges
18.1 Introduction
18.2 Philosophical Issues
18.3 Ecological Issues
18.4 Sensor Technology
18.5 Acoustic Computations and Modeling
18.6 Public Information
18.7 Monetary Issues
References
Index
End User License Agreement
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Guide
Cover
Table of Contents
Preface
Begin Reading
List of Tables
Chapter 3: The Role of Sound in Terrestrial Ecosystems: Three Case Examples from Michigan, USA
Table 3.1 Initial search criteria and number of recordings of the spring peeper determined by filtering the frequency in which spring peeper calls occur
Table 3.2 Date and time of first call of the spring peeper (FSPC) at Twin Lakes, Cheboygan, MI
Table 3.3 C3 – Site, location, year, start day, end day, and number of recordings
Table 3.4 C3 – Site, location, year, start day, end day, and number of recordings
Table 3.5 C3 – Analysis of variance of NDSI versus year (all data)
Table 3.6 C3 – Tukey pairwise comparisons NDSI versus year (all data) where grouping information is based on 95% confidence. Means that do not share a letter are significantly different
Table 3.7 C3 – Analysis of variance of NDSI versus year (June only)
Table 3.8 C3 – Tukey pairwise comparisons of NDSI versus year (June only) where grouping information is based on 95% confidence. Means that do not share a letter are significantly different
Chapter 7: Biodiversity Assessment in Temperate Biomes using Ecoacoustics
Table 7.1 Annual distribution (September 2015 to July 2016) of acoustic events at Carpaneta (44°13'34”N, 10°07'16”E, 290 m a.s.l., Fivizzano, Italy), only categories >0 where considered and sorted according to the code. #, number of events; code, event code; Tot, total number of events. From this Table four examples are reported in Figure 7.6.
Chapter 8: Biodiversity Assessment in Tropical Biomes using Ecoacoustics: Linking Soundscape to Forest Structure in a Human-dominated Tropical Dry Forest in Southern Madagascar
Table 8.1 Best fit linear mixed models between BIO and forest class during each seasonal period.
Table 8.2 Best fit linear mixed models between BIO and forest structure variable(s) during each seasonal period.
Chapter 10: Integrating Biophony into Biodiversity Measurement and Assessment
Table 10.1 Mathematical tools used to estimate diversity parameters from species surveys. “Importance” refers to the relative dominance or prevalence of a species.
Table 10.2 Possible responses to interference from mechanical sounds and their associated trade-offs.
Chapter 12: Connecting Soundscapes to Landscapes: Modeling the Spatial Distribution of Sound
Table 12.1 Models produce a Table of response variables that have the strongest to weakest relationship to a target variable (e.g. biophony, geophony, technophony). This Table shows the rank of importance of the top 10 environmental variables associated with biophony, technophony, and geophony used to model the acoustic-environmental relationships in the Kenai National Wildlife Refuge, Alaska, over winter 2011–2012. Source: Mullet et al. (2016). Reproduced with permission of Springer.
Chapter 15: Urban Acoustics: Heartbeat of Lansing, Michigan, USA
Table 15.1 Classification of acoustic recording sites according to class, habitat, and class-habitat combination.
Table 15.2 Minimum and maximum mean values for five acoustic indices for each of the urban-rural combinations
Chapter 16: Analytical Methods in Ecoacoustics
Table 16.1 A MATLAB script outputs the variables in csv file format for each sound recording.
Table 16.2 The acoustic indices in this R script include computations for multiple acoustic indices. As there are several indices of the same name but computed slightly differently, the three letters following the indices indicate the source of the indices: Stuart Gage (shg), Soundecology (sou), Seewave (see).
Table 16.3 Species codes and names for species included in Figure 16.7.
Ecoacoustics
The Ecological Role of Sounds
Edited by
Almo Farina
Urbino University, Italy
Stuart H. Gage
Michigan State University, East Lansing, Michigan, USA
This edition first published 2017
© 2017 John Wiley and Sons
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The right of Almo Farina and Stuart H. Gage to be identified as the authors of this work/the editorial material in this work has been asserted in accordance with law.
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Library of Congress Cataloging-in-Publication Data
Names: Farina, Almo, editor. | Gage, S. H., editor.
Title: Ecoacoustics : the ecological role of sounds / edited by Almo Farina, Urbino University, IT, Stuart H Gage, Michigan State University, East Lansing, MI, US.
Description: First edition. | Hoboken, NJ : John Wiley & Sons, Inc., 2017. | Includes bibliographical references and index.
Identifiers: LCCN 2017003603 (print) | LCCN 2017005379 (ebook) | ISBN9781119230694 (cloth) | ISBN 9781119230700 (pdf) | ISBN 9781119230717 (epub)
Subjects: LCSH: Landscape ecology. | Nature sounds. | Bioacoustics. | Ecosystem health. | Biodiversity.
Classification: LCC QH541.15.L35 E247 2017 (print) | LCC QH541.15.L35 (ebook) | DDC 577-dc23
LC record available at https://lccn.loc.gov/2017003603
A catalogue record for this book is available from the British Library.
Cover Design: Wiley
Cover Image: Courtesy of Stuart H. Gage
List of Contributors
Anne C. Axel
Department of Biological Sciences
Marshall University
Huntington
USA
Giuseppa Buscaino
BioAcousticsLab
National Research Council (IAMC-CNR) - Detached Unit of Capo Granitola (TP)
Italy
Maria Ceraulo
Department of Pure and Applied Sciences
University of Urbino
Urbino
Italy
Almo Farina
Department of Pure and Applied Sciences
University of Urbino
Urbino
Italy
Francesco Filiciotto
BioAcousticsLab
National Research Council (IAMC-CNR) - Detached Unit of Capo Granitola (TP)
Italy
Susan Fuller
Queensland University of Technology
Brisbane
Australia
Stuart H. Gage
Department of Entomology
Michigan State University
East Lansing
USA
Wooyeong Joo
Choongnam
Seocheon-gun
Maseo-Myeon
Geumgang-ro
South Korea
Eric P. Kasten
Michigan State University
East Lansing
USA
Bernie Krause
Wild Sanctuary
Glen Ellen
USA
David Monacchi
Conservatorio Gioachino Rossini
Pesaro
Italy
Timothy C. Mullet
Ecological Services
US Fish and Wildlife Service
Daphne
Alabama
USA
Brian Michael Napoletano
Centro de Investigaciones en Geografía Ambiental
Universidad Nacional Autónoma de México
Morelia
Michoacán
México
Susan E. Parks
107 College Place
Syracuse
USA
Gianni Pavan
CIBRA
University of Pavia
Italy
Nadia Pieretti
Department of Pure and Applied Sciences
University of Urbino
Urbino
Italy
Marisol A. Quintanilla-Tornel
Plant and Environmental Protection Sciences
University of Hawaii
Manoa
USA
Lyndsay Rankin
Northern Illinois University
DeKalb
USA
Denise Risch
Scottish Association for Marine Science (SAMS)
Oban
Scotland
UK
Michael Towsey
Queensland University of Technology
Brisbane
Australia
Preface
Discovering the importance of sound in natural processes is an important legacy of bioacoustics and human acoustics, two disciplines that have developed in the second half of the twentieth century. At that time, Aldo Leopold and Rachel Carson used acoustics to describe relevant phenomena like animal migration or the effect of chemical pollution on reproductive success of breeding birds but acoustics technology methods were rare. Their heritage is an important baseline for a new ecological perspective in the scientific investigation of sound, known as ecoacoustics, a discipline that incorporates and integrates the study of sound in both ecological and human systems.
Sound is an important phenomenon including behavioral functions that range from mate performance to territory defense and social cohesion and has recently been shown to be a key issue in ecological processes. The Earth emits geological, biological, and human sounds within the biosphere, creating a sonic context that characterizes ecosystems at different spatial and temporal scales and has consequences that can affect many ecological processes. Vocal animals have a direct relationship with habitat suitability and the vocal performance of other organisms, further confirming the energy investment required to produce acoustic signals and the trade-off between such performances, other life traits, and the availability of resources needed for their survivorship.
All young disciplines, including ecoacoustics, have difficulty in tracing historical origins so there is no precise date allocated to its foundation. The use of the term “ecoacoustics” was suggested at a meeting in June 2104 at the Museum of Natural History in Paris where “soundscape ecology” was also suggested as an alternative. The assembly decided that ecoacoustics was all-inclusive in studies of ecologically based sound and thus included soundscape ecology.
With this book, we offer examples of studies, theoretical concepts, and methodologies that have evolved over the past decades in an attempt to provide a synthesis of the new discipline of ecoacoustics, although we emphasize that these are only a subset of possible examples. This book is not a celebrative edition of a consolidated ecological discipline but a contribution to transmit the principles and ideas of ecoacoustics to a wider audience. We believe that the examples of these aspects of ecoacoustics will provide an incentive for others interested in ecological sounds, including those in the sciences and the arts, to pursue their research, applying sound to solve ecological problems and to educate the next generation about the importance of ecological sounds to the survivorship of the human race.
The 18 chapters in this book cover important topics to assist others to understand the ecological significance of sounds. This introduction to ecoacoustics is intended for all who are interested in or concerned about the ecosystems in which we live and utilize for the resources that they provide.
Almo Farina and Stuart H. Gage
Chapter 1Ecoacoustics: A New Science
Almo Farina1 and Stuart H. Gage2
1Department of Pure and Applied Sciences, Urbino University, Urbino, Italy
2Department of Entomology, Michigan State University, East Lansing, USA
1.1 Ecoacoustics as a New Science
Ecoacoustics is the ecological investigation and interpretation of environmental sound (Sueur and Farina 2015). It is an emerging interdisciplinary science that investigates natural and anthropogenic sounds and their relationships with the environment over multiple scales of time and space. Ecoacoustics is inclusive of the realms of ecological investigation including populations, communities, ecosystems, landscapes, and biotic regions of the Earth system. Studies of ecoacoustics in these realms can include terrestrial, freshwater, and marine systems. Ecoacoustics thus extends the scope of acoustic investigations, including bioacoustics and soundscape ecology.
Ecoacoustics studies involve the investigation of sound as a subject to understand the properties of sound, its evolution, and its function in the environment. Ecoacoustics also considers sound as an ecological attribute that can be utilized to investigate a broad array of applications including the diversity, abundance, behavior, and dynamics of animals in the environment. To facilitate this emerging new science and the investigators interested in the study of ecoacoustics, the International Society of Ecoacoustics (ISE) has recently been established and details can be found at https://sites.google.com/site/ecoacousticssociety/. For definitions of other acoustics disciplines, see Pijanowski et al. (2011) and Farina (2014).
1.2 Characteristics of a Sound
Sound is a flow of energy in the form of lateral vibrations through a medium capable of oscillation. Sound is additive, meaning separate waves combine to form a single signal. The ear and brain manually separate this into distinct waves. The number of vibrations a sound produces per second is called frequency with a unit measurement of hertz. A spectrogram, commonly used to “see” a sound recording, is shown in Figure 1.1 where time is on the x-axis (seconds), frequency is on the y-axis (kilohertz), and sound intensity (energy) is on the z-axis. The spectrogram shown is a visual representation of a sound. The creation of a sound image requires that the sound be processed using fast Fourier transform (FFT). Creating a spectrogram using the FFT is a digital process. Digitally sampled data, in the time domain, is divided into components, which usually overlap, and Fourier transformed to calculate the magnitude of the frequency spectrum for each component. Each component then corresponds to a vertical line in the image – a measurement of magnitude versus frequency for a specific moment in time. The spectra or time plots are then “laid side by side” to form the image. The sound shown in Figure 1.1 was recorded in monaural at 22 050 Hz at site LA00 (45.53320, –84.291960 decimal degrees) on May 4 2009 at 0600h. Most of the sound in this recording occurs between frequencies 2 and 6 kHz with some high-frequency sounds occurring about 8 kHz and some low-frequency sounds at about 0.5 kHz. For those interested in the details of a mathematical treatment of acoustic signal processing, please see Hartmann (1998).
Figure 1.1 A spectrogram from a recording made at site LA00 (45.53320, –84.291960 in decimal degrees) on May 4 2009 at 0600h.
1.3 Sound and its Importance
Hearing is one of the five key senses (hearing, vision, touch, smell, and taste) that allow organisms in the animal kingdom to relate with the environment. Hearing is an intrinsic component of the life of many organisms, including humans. Many animals use hearing to receive signals made by the environment or by other organisms. They derive meaning from these signals, which can range from danger to courtship, and these sound signals can often mean survival or a source of food. The importance of sound to humans has diminished due to evolution, since we have built habitation and created technology that we think protects us from the outside world. As our world has become louder, due to our increasing population and technological development, we are becoming more sensitive to the importance of sound. Sound is the heartbeat of the biosphere, the places on Earth where life exists. If we can measure this heartbeat, we can determine the condition of the biosphere. When one scales from biosphere, to eco-region, to landscape, to ecosystem or to habitat, the sounds produced within each of these realms can determine the condition of that realm if we can determine the type of sounds being emitted.
1.4 Ecoacoustics and Digital Sensors
Ecoacoustics has been recognized as an approach to the study of species communication and census species over long periods of time. There have been significant changes in monitoring technology. Ecoacoustics has been developed thanks to instrumentation and analytical techniques. For instance, the microphone is an important sensor because this single instrument can serve many purposes for ecological investigations when connected to a recorder. The array of ecological attributes that can be determined by a microphone, which is an analog for hearing, is broad compared to other types of available sensors (smell, taste, vision, touch). Sensors which measure other senses are important but are not yet fully applicable to the field as is the microphone, mainly due to cost.
Studies of animal attributes by listening to their sounds can be a fruitful undertaking, especially if one enjoys listening to and documenting the occurrence of animal species during the dawn or nighttime chorus. However, there are many pitfalls, including change in species composition over season and time of day and the potential for misidentification of species. Errors in species identification are introduced because an observer cannot be at multiple places at the same time. Within the past decade, analog tape recorders have been replaced by digital recorders. Clocks have been added to recorders so that recordings can be made at specific times and other environmental sensors have been incorporated in the same recording machine. The length of a recording period was previously limited due to high power consumption by processors. Just a few years ago, it was not possible to record in a remote place without being there to manage the recording unit. Today, sound recorders can be programmed to suit a project’s objective, can store many recordings on removable digital media and can remain active in the field for months without intervention. This change in technology has given rise to the use of sound as an ecological attribute. Modern acoustic sensors can be used to investigate several attributes of ecological significance. These may include practical and theoretical aspects of the environment, including acoustic identification of species in terrestrial and aquatic ecosystems; the vocal behaviors of specific organisms and their physiology; the study of noise pollution; and measuring ecological processes under a climate change scenario.
1.5 Ecoacoustics Attributes
A microphone and an automated recorder can provide an array of attributes that can have significant implications for theoretical and applied ecology. Important processes can be remotely investigated, including the number of species present, phenology of sound, trophic interactions, biological diversity, level of disturbance, diurnal and seasonal change of acoustic activity, level of habitat health, acoustic interactions between species, and complexity of the soundscape.
1.5.1 Population Census
Sound as a tool to survey animals has been utilized for decades (Ralph and Scott 1981). Birds are monitored by listening to the morning chorus and identifying the species based their signals at prescribed listening posts. Gage and Miller (1978) describe a long-term study using this method. Similar monitoring methods have utilized sound to determine species occurrence and abundance of amphibians using nighttime signaling (Karns 1986). The Breeding Bird Survey of North America (BBS) has been ongoing since the 1960s (Robbins and van Welzen 1967); it uses sound to determine avian species occurrence and this eco-region assessment has provided one of the longest records of bird species occurrence in North America, thus enabling the assessment of change in avian species. The surveys conducted by the BBS take place during the peak of the breeding season. The BBS routes are 24.5 miles long and there are 50 stops at every 0.5 mile along the route. Routes are randomly located in order to sample habitats that are representative of the entire region (Sauer et al. 1997). Although surveys are conducted differently in Europe, sound is used to determine the occurrence of bird species in many countries. The Pan-European Common Bird Monitoring Scheme commenced in January 2002; its main goal is to use common birds as indicators of the general state of nature using scientific data on changes in breeding bird populations across Europe (Voříšek et al. 2008).
1.5.2 Biological Diversity
Biological diversity is a complex ecological attribute to measure because it requires documentation of all species that inhabit a place. In addition, seasonal change can change biological diversity. Therefore, vegetation is commonly used as a surrogate for biological diversity. Measurement of the sound diversity at a site can begin to add information to the determination of biological diversity (Farina et al. 2005; Fuller et al. 2015; Sueur et al. 2008; Tucker et al. 2014).
1.5.3 Habitat Health
Habitat health is a relative term, but when defined by the types of sounds emitted from the site, these signals can provide an indication of the quality of that place. In fact, sounds differ in type and character depending on the types of vegetation and food available to the organisms. Benchmarks need to be established for urban, forest, grassland, and desert systems so that sounds in arrays of these systems can be compared (Fuller et al. 2015; Qi et al. 2008).
1.5.4 Time of Arrival/Departure of Migratory Species
The changing global climate is causing shifts in the arrival and departure times of animals that inhabit terrestrial and marine ecosystems (MacMynowski et al. 2007). Shifts in the areal pathways used by migratory animals to move from wintering sites to breeding sites may also be determined by measuring sounds along these marine or terrestrial routes.
1.5.5 Diurnal Change
Daily patterns of change in animal behavior can be determined by measuring sounds emitted from a place (Farina et al. 2015). Many factors can cause diurnal change and the measurement of sound along with weather information can help to describe the magnitude of the change (Gage and Axel 2013).
1.5.6 Seasonal Change
Seasonal change caused by climate shifts or physical disturbance of the Earth system due to large-scale natural events or by land use change due to human development can be measured by recording sounds in a place. Seasonal change is also a natural occurrence. In temperate regions, there are shifts in animal behavior as seasons change. In spring, migratory populations of marine and terrestrial animals (mammals, fish, birds) move from overwintering habitats to breeding locations that can be far distant and require a great expenditure of energy. Food and habitat resources change and during this period, the sounds emitted from these organisms differ as they enter the breeding cycle (Gage and Axel 2013).
1.5.7 Competition for Frequency
The acoustic niche hypothesis (Krause 1993), an early version of the term biophony (sounds made by organisms), describes the acoustic bandwidth partitioning process that occurs in still wild biomes by which nonhuman organisms adjust their vocalizations by frequency and time-shifting to compensate for acoustic habitat occupied by other vocal creatures. Thus each species evolves to establish and maintain its own acoustic bandwidth so that its voice is not masked (Malavasi and Farina 2013). For instance, examples of clear partitioning and species discrimination can be found in the spectrograms derived from the biophonic recordings made in most uncompromised tropical and subtropical rainforests (Krause 1993).
1.5.8 Trophic Interactions
Many species of organisms do not emit audible sounds but those that do emit acoustic signals may depend on organisms that do not. Therefore, the presence of those that do not emit sounds may be deduced by quantifying the sounds for those that produce auditory signals. Consider birds and their food source. A wood thrush sings a beautiful song in undisturbed forests and searches and feeds on worms and other food that occurs on the forest floor. Although the food sources do not make audible sounds, the wood thrush would not occur in the habitat if it were not for the resources found there. When we hear the sound of the thrush, we can infer that there are food resources nearby and thus identify trophic interactions.
1.5.9 Disturbance
Disturbance can be caused by natural events (hurricanes, volcanoes, fires, floods) or by human-caused events (mining, urbanization, forest harvest, spraying). Such events are characterized by acoustic emissions. The measurement of sounds (noise) caused by disturbance can indicate the type and duration of the disturbance. The term technophony, the sounds made by machines, is used to characterize disturbance and can occur when an overabundance of machine sounds from aircraft, automobiles, watercraft, chain saws, etc. dominates a habitat. Usually technophony occurs at lower sound frequencies than biota so it is possible to use sound to quantify disturbance.
1.5.10 Sounds of the Landscape and People
Every landscape has a specific acoustic signature that is the result of the mixture of all the physical and biological acoustic agents. The measurement of the sounds emitting from a place can provide an enjoyable experience to the listener. Listening to recordings of the howl of a coyote, the yodel of a common loon or the song of a thrush can conjure up memories of a place long forgotten. Figure 1.2 provides a summary of the value of sound ranging from population census to quality assessment of the landscape for human well-being.
Figure 1.2 Ecoacoustics has several competencies in environmental surveys, ranging from population census to quality assessment of landscape for human well-being.
1.6 Ecoacoustics and Ecosystem Management
There are two aspects of sound that relate to ecosystem management:
as a
response indicator
by estimating the diversity of vocal organisms; determining the relative proportions of human and natural activity; characterizing the daily and long-term trends of human and biological activity; and measuring sound in response to changes in land use.
as a
stress indicator
by examining the effects of human activity on organism communication during critical functions (e.g. reproduction, food tracking, migration, etc.); determining the causes of natural population declines in organisms sensitive to human disturbance or to climate change (Krause and Farina 2016).
Sound can also be used as a management tool to regulate the amount of noise that is tolerable to humans (Farina 2014, pp. 263–296). Sound maps of urban areas, airports, manufacturing zones, and parks can be useful tools to guide the development of sound abatement regulations. Measurement of sound can be used to identify and characterize the amount of technology (trucks, cars, boats, ships, jet skis, snow machines) and the length and intensity of human-kept animals (dogs, roosters) which can be a local disturbance.
1.7 Quantification of a Sound
1.7.1 Species Identification
One can listen to the sounds in a recording and identify the entities recorded. Haselmayer and Quinn (2000) compared field observations using the point-count method of species identification by listening to recordings made at the time of the point-count and found that they are highly correlated. Joo (2009) conducted a breeding bird survey and also identified species in simultaneous recordings and found a high correlation as well. Kasten et al. (2012) provide a method to catalog species heard in a recording using a web-based tool. Automated species identification has been found to be complex due to the variability within species of songs and calls and the overlap in frequencies caused by sound emitters. Butler et al. (2007) used signatures extracted from spectrograms to search other spectrograms for that signature providing the probability of match to that signature. Match probabilities are closer to 1 for simple signatures (insects, amphibians) compared to more complex signatures (birds). However, new approaches to this problem have made major improvements in automation of species identification (Acevedo et al. 2009; Dong et al. 2015; Duan et al. 2013).
To quantify sounds recorded in the environment, the spectrogram representation can be used to create acoustics indices by dividing the spectrogram into frequency intervals and counting the pixels in each interval (Napoletano 2004). The spectrogram can also be used to select signatures of a species from the image and search a series of spectrograms for that signature (Butler et al. 2007). Since these studies were undertaken, there has been considerable improvement in the development of acoustics indices and species recognition algorithms.
1.7.2 Acoustic Indices
Acoustic indices are derived from environmental recordings that do not depend on the species that occur in the recordings but rather on the characteristics of the recording, including the diversity of the sounds in the recording, the complexity of the sounds, the degree of evenness of the sounds, or ratios of frequencies in the sounds.
Seewave, a package in R developed by Sueur et al. (2008), provides functions for analyzing, manipulating, displaying, editing, and synthesizing time waves. This package processes time analysis (oscillograms and envelopes), spectral content, resonance quality factor, entropy, cross-correlation and autocorrelation, zero crossing, frequency coherence, dominant frequency, analytic signal, 2D and 3D spectrograms. Seewave enables a user to compute acoustic indices including H (Sueur et al. 2008), the Acoustic Complexity Index (ACI) (Pieretti et al. 2011), and the Normalized Difference Soundscape Index (NDSI) (Kasten et al. 2012).
Soundecology, another R package focusing on acoustics, was developed by Villanueva-Rivera et al. (2011) and enables a user to compute values for acoustic indices where one can specify the acoustic index and its parameters. Acoustics indices in R-Soundecology include the ACI (Pieretti et al. 2011), the Acoustic Diversity Index (Villanueva-Rivera et al. 2011), the Acoustic Evenness Index (Villanueva-Rivera et al. 2011), the Bioacoustic Index (Boelman et al. 2007) and the NDSI (Kasten et al. 2012). These indices and other techniques used to interpret environmental recordings are discussed in Chapter 16. A procedure to detect and identify acoustic events, the Ecoacoustic Event Detection and Identification (EEDI) developed by Farina et al. (2016). is powered by free access software, the SoundscapeMeter 2.0 (Farina and Salutari 2016).
