This is a very interesting subject, and even more after looking the video. However, my answer about the usefulness on the utilization of soundscapes as a reliable method to evaluate habitats is a limited yes. Efectively the use of sounds expands our understanding of some patterns and processes (even beyond the natural human capacitites; I work with ultrasonic bat calls). However, I think that can be useful as a complementary method, but not as an stand-alone technique to evaluate based solely on this.

There are some inherent problems; perhaps the most important is that you can evaluate only the species that produces identifiable sounds (i.e. some animals), so your are evaluating based on a limited group and the result will be biased towards the environmental impacts on those species. Of course, could be specific situations where can be clearly useful, but I feel that those will tend to be scarce. Also, could be concerns on the evaluation of abundances, specially if you are using automated or non supervised recordings.

Perhaps one of the best applications for the use of soundscapes on ecosystems management is to sensibilize the general public on the environmental education and to promote conservation; Krause's video is a good example of it.

This is a very interesting subject, and even more after looking the video. However, my answer about the usefulness on the utilization of soundscapes as a reliable method to evaluate habitats is a limited yes. Efectively the use of sounds expands our understanding of some patterns and processes (even beyond the natural human capacitites; I work with ultrasonic bat calls). However, I think that can be useful as a complementary method, but not as an stand-alone technique to evaluate based solely on this.

There are some inherent problems; perhaps the most important is that you can evaluate only the species that produces identifiable sounds (i.e. some animals), so your are evaluating based on a limited group and the result will be biased towards the environmental impacts on those species. Of course, could be specific situations where can be clearly useful, but I feel that those will tend to be scarce. Also, could be concerns on the evaluation of abundances, specially if you are using automated or non supervised recordings.

Perhaps one of the best applications for the use of soundscapes on ecosystems management is to sensibilize the general public on the environmental education and to promote conservation; Krause's video is a good example of it.

Dear Luis,

Thanks a lot for your high-quality advice.

Hello,

I think sound recording is a really promising technique for habitat assessment. Like for visual assessment of habitat, I imagine that sound recording techniques need in a first step to focus on some taxonomic groups (assumed to be good indicators) to have seperate index. I guess this first step is necessary to be able to describe the different components of the "biophony", which represent some components of the habitat. Several taxonomic groups are already well described using sound, for instance birds, amphibians, bats, grasshopers, ... with even automated techniques.

Of course I don't think sound recording can be used to assess all the components of a habitat (how to detect a soil pollution with a microphone for instance :-). It can only be complementary to other techniques, but quite promising as it can perhaps be possible to evaluate birds, grasshopppers, amphibians,... from a single record?! Also, it is quite easy to standardize, making comparable index from site to site, ...

Some interesting papers on the subject...

Digby-et-al_2013_Methods-in-Ecology-and-Evolution

Penone-et-al_2013_Conservation-Biology

Accoustic technique can even be used to geolocalise species at a certain scale...

Mennill-et-al_2012_Methods-Ecology-Evolution

In an ecosystem the "sound" of silence fits to death. Ecosystem maintenance and sustainability are characterized by the various sounds/voices of life levels.

Sound playback is used to attract (avian) species, including migratory species at stop-over sites. The fact they are attracted to sound should give some hints about habitat attractiveness. Many sounds imply good living conditions perhaps creating or maintaining social hot spots in certain environments or during certain periods of the year.

Sounds perceived from a distance provide information about species identity or individual features (e.g. motivation, intention, geographic origin, age, body condition.....).

Well, as John Cage tells us with his 4'33'' there is no such thing as silence. So, sound based parameters for evaluating (=quantifying) environmental impact could be possible. However, the construction of indicators rely upon the ability of such things to quantify both the physical magnitude and uncertainties related to a given measurement. In this manner some difficulties may arise for the validation of such (beautiful) method: What about the standardization of the method? What about the construction of background and reference values imperative to set the physical magnitude and the measurement units related to this technique? What about the amplitude and resolution of it? It seems to me that those would be quite challenging issues.

Does it worth to have a soundscape library which shows us different conditions that a habitat might have? for example we have image library which make relations between particular images to the health of habitat. Can we have such relations between soundscapes and habitats?

Here the answer is two times dual, because the nature of environment and the nature of the recording media.

First, images: When we record an image of the habitat, normally we are recording the prescence of still objects that will remain in the place for certain amount of time. I have colleages doing fuel accumulation photoseries on forests, that implies taking pictures of the exactly same spot once every several years; those spots could be subject of forest fires in the meanwhile; that implies a habitat change in the middle-long term. However, normally an image library is not as precise as that. We recorded with pictures several aspects of a habitat, but normally are those aspects of the habitat that WE consider relevant to document as "representative" of it.

Second, sounds: The nature of sound recording is to capture an inmediate processes (a sound exists only while is being produced). Considering only biosounds, those are more dynamic in recordings than images. They are subject to seasonal changes (have you attempted to record mating calls in a non mating season...?). The other difference is that a habitat image normally represents a certain amount of terrain, with certain direction and distance depending on visibility of the habitat. A sound recording normally is omnidirectional and the recorded distance depands on the sensibility of the microphone and the acoustic buffering condition of the hábitat.

Does the soundscape recording reflects the habitat quality? Depends on when and how you are documenting the records of it. The nature of a visual record is to be more "directed" by our personal decision but more steady in time, while a sound record normally is less "selective" (as is omnidirectional), but is highly depending on the time of recording.

Food for thought.

I have not had time to see the film so if I am repeating points already made - apologies!

Perhaps the analysis of the bio-soundscape demands a different sort of approach.

It has always struck me how efficiently - like the pieces of a jigsaw -the various species that comprise a stable eco-system 'carve-up' the available survival space.

The work of Schneider and Kay on the thermodynamics of ecosystems (reference below) shows that ecosystems that are disturbed from equilibrium exhibit a tendency to maximize the paths for energy dissipation as an intrinsic part of the recovery process.

Their work suggests that a healthy ecosystem might be quantifiable in thermodynamic terms.

In the light of their work observable repeated patterns of the evolutionary process might be better understood.

One such repeated pattern occurs when a new environments are colonized for the first time. Such events are often associated with the emergence mega-fauna. It seems that the new environmental resource allows for basic body designs to rapidly 'expand' into the available survival space. These basic body designs dominate the landscape at every level of scale because of a lack of competition. Their predominance also inhibits the evolution of competing design concepts. So, although these mega-ecosystems exhibit stability this stability belies an underlying thermodynamic dis-equilibrium. This underlying instability often manifests itself as a consequence of natural disasters. The inefficiency of basic body designs make the meg-fauna particularly vulnerable to changes in the environment.

Natural disasters afford alternative body-designs an opportunity to quickly evolve and fill the environmental survival space with a greater variety of forms that can exploit the available survival space more efficiently and allow for an increase in the available paths for energy dissipation. This invariably marks the end of the reign of the mega-fauna.

The Fractal Catalytic Model of living processes and indeed, the empirical evidence of numerous studies, suggests that fractal organization is a fundamental characteristic biological systems that may arise as a direct consequence of the influence of fundamental thermodynamic principles on the process of evolution.

If we consider the soundscape primarily as another means for energy dissipation via structure (communication sounds), then any analysis of how intentional animal sounds have evolved to utilize this resource should reveal a fractal organization. Specifically - 1/f? relation between the log of frequency against the Log of energy (my maths is awful so this might be a little inaccurate).

Several years ago I worked at the Henry Doorly Zoo in Omaha, NE. There was a group of researchers from Boys Town (also in Omaha, NE) to assess hearing development and vocalizations of large carnivores. The hope was to be able to determine individuals based on vocalization characteristics and to possibly use this to evaluate wild populations at some point in the future. I went back to school before the end of the project. So, I'm not sure what was found or if it still going on. But, it might be something to look into if this fits into your interests.