The Duality of Sounds: Ambient and Communication

Farina, Almo; Gage, Stuart H.

doi:10.1002/9781119230724.ch2

Cited by 11 publications

(14 citation statements)

References 73 publications

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“…Once we have this linear energy growth bound, there are many ways to show that the solution has finitely many ends in the sense of [21] as well as the refined asymptotic behavior of u at infinity; see, for example, [21,28,39,74].…”

Section: Energy Growth Bound: Proof Of Theorem 22mentioning

confidence: 99%

Finite Morse Index Implies Finite Ends

Wang

Wei

2019

Comm Pure Appl Math

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We prove that finite Morse index solutions to the Allen-Cahn equation in R 2 have finitely many ends and linear energy growth. The main tool is a curvature decay estimate on level sets of these finite Morse index solutions, which in turn is reduced to a problem on the uniform second-order regularity of clustering interfaces for the singularly perturbed Allen-Cahn equation. Using an indirect blowup technique, in the spirit of the classical Colding-Minicozzi theory in minimal surfaces, we show that the obstruction to the uniform second-order regularity of clustering interfaces in R n is associated to the existence of nontrivial entire solutions to a (finite or infinite) Toda system in R n 1 . For finite Morse index solutions in R 2 , we show that this obstruction does not exist by using information on stable solutions of the Toda system.

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Section: Energy Growth Bound: Proof Of Theorem 22mentioning

confidence: 99%

Finite Morse Index Implies Finite Ends

Wang

Wei

2019

Comm Pure Appl Math

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“…Wildlife acoustics (USA; https://www.wildlifeacoustics.com), Lunilettronik (ITL; http://www.lunilettronik.it), and Frontier Labs (AU; http://www.frontierlabs.com.au) are the main producers of professional terrestrial and aquatic recorders for bioacoustic and ecoacoustic investigations. The use of low-cost recorders has been recently proposed [69] and new devices (e.g., Audio Moth (https://www.openacpisticdevices.info/)) tested [70] as a further solution to deploy recorders in unsafe places where human vandalism or animal damage discourage the use of more expensive devices.…”

Section: Hardwarementioning

confidence: 99%

Ecoacoustics: A Quantitative Approach to Investigate the Ecological Role of Environmental Sounds

Farina

2018

Mathematics

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Ecoacoustics is a recent ecological discipline focusing on the ecological role of sounds. Sounds from the geophysical, biological, and anthropic environment represent important cues used by animals to navigate, communicate, and transform unknown environments in well-known habitats. Sounds are utilized to evaluate relevant ecological parameters adopted as proxies for biodiversity, environmental health, and human wellbeing assessment due to the availability of autonomous audio recorders and of quantitative metrics. Ecoacoustics is an important ecological tool to establish an innovative biosemiotic narrative to ensure a strategic connection between nature and humanity, to help in-situ field and remote-sensing surveys, and to develop long-term monitoring programs. Acoustic entropy, acoustic richness, acoustic dissimilarity index, acoustic complexity indices (ACItf and ACIft and their evenness), normalized difference soundscape index, ecoacoustic event detection and identification routine, and their fractal structure are some of the most popular indices successfully applied in ecoacoustics. Ecoacoustics offers great opportunities to investigate ecological complexity across a full range of operational scales (from individual species to landscapes), but requires an implementation of its foundations and of quantitative metrics to ameliorate its competency on physical, biological, and anthropic sonic contexts.

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“…AIs allow us to represent an acoustic recording as a single value and analyze biophony and anthropophony at different ecological levels. AIs depend on the vocalization of the species and the characteristics of the recordings, including the diversity, density and complexity of the sounds in the recordings coupled with the ratio of the sounds throughout frequencies [ 20 ]. An ideal AI should be able to measure the variation of acoustic energy over temporal and spatial scales in accordance with the vocalizing species in the acoustic recordings.…”

Section: Introductionmentioning

confidence: 99%

“…AIs were initially created for studying terrestrial ecosystems [ 20 ] and have been successively applied in marine environments [ 21 , 22 , 23 , 24 , 25 ]. Nevertheless, AIs in marine studies have produced mixed results, particularly when anthropogenic noise was present [ 26 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

“…Loud noise (i.e., air guns) mask the weaker biological signals [ 24 ], whereas continuous noise from vessels covers the frequency band used by fish and impedes the selection of a usable part of the spectrogram [ 21 ]. There are over 30 AIs in use in terrestrial ecoacoustics [ 20 , 28 ]. Some of the AIs, such as the acoustic complexity index (ACI) [ 29 ], acoustic diversity index (ADI) [ 30 , 31 ] and bioacoustic index (BI) [ 32 ], have been utilized to explore trends in biophony produced by various species of mammals, fish and crustaceans [ 26 , 27 , 33 ].…”

Section: Introductionmentioning

confidence: 99%

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A Complexity-Entropy Based Approach for the Detection of Fish Choruses

Siddagangaiah

Chen

et al. 2019

Entropy

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Automated acoustic indices to infer biological sounds from marine recordings have produced mixed levels of success. The use of such indices in complex marine environments, dominated by several anthropogenic and geophonic sources, have yet to be understood fully. In this study, we introduce a noise resilient method based on complexity-entropy (hereafter named C-H) for the detection of biophonic sounds originating from fish choruses. The C-H method was tested on data collected in Changhua and Miaoli (Taiwan) during the spring in both 2016 and 2017. Miaoli was exposed to continual shipping activity, which led to an increase of ~10 dB in low frequency ambient noise levels (5–500 Hz). The acoustic dataset was successively analyzed via the acoustic complexity index, the acoustic diversity index and the bioacoustic index. The C-H method was found to be strongly correlated with fish chorusing (Pearson correlation: rH < −0.9; rC > 0.89), and robust to noise originating from shipping activity or natural sources, such as wind and tides (rH and rC were between 0.22 and −0.19). Other indices produced lower or null correlations with fish chorusing due to missed identification of the choruses or sensitivity to other sound sources. In contrast to most acoustic indices, the C-H method does not require a prior setting of frequency and amplitude thresholds, and is therefore, more user friendly to untrained technicians. We conclude that the use of the C-H method has potential implications in the efficient detection of fish choruses for management or conservation purposes and could help with overcoming the limitations of acoustic indices in noisy marine environments.

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The Duality of Sounds: Ambient and Communication

Cited by 11 publications

References 73 publications

Finite Morse Index Implies Finite Ends

Finite Morse Index Implies Finite Ends

Ecoacoustics: A Quantitative Approach to Investigate the Ecological Role of Environmental Sounds

A Complexity-Entropy Based Approach for the Detection of Fish Choruses

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