GEO.fr: When exactly did we start recording the sounds of nature?
Jérôme Sueur: The recording of the sounds of nature began during the Second World War, mainly under the seas and oceans. We were trying to understand the sounds that could correspond to enemy military activities. Bioacoustics then developed with the evolution of recording techniques after the war, in the 1950s. The pioneers started with tape recorders that were heavy and bulky but which could still come out of laboratories and studios.
What is bio-acoustics, and what is the difference with eco-acoustics?
Bioacoustics is the study of animal sound behavior. We seek to know why and how animals produce and perceive sounds, what roles these sounds play in their lives. Much more recently, in the 2010s, eco-acoustics was born. This discipline seeks to deal with questions of ecology through sound.
Who were the pioneers of this new discipline?
In fact, there are two complementary practices around eco-acoustics: on the one hand, the scientific world around universities and research institutes, and, on the other hand, the world of “audio-naturalists”. who passionately record the sounds of nature from a more aesthetic perspective. At first, the recordings of scientists and audio-naturalists focused on species. We were trying to record a blackbird, a tree frog or a grasshopper by excluding all other sounds, a bit like it is done in wildlife photography. But Bernie Krause (musician born in 1938 in the United States, Editor’s note) has changed this approach, broadening the listening angle by recording soundscapes. He went, in a way, from telephoto to wide-angle, from ethology to ecology.
⋙ General knowledge quiz: do you know the name of these animal sounds?
What are soundscapes made of?
Still according to Bernie Krause, a soundscape is made up of three main sound sets: “biophony”, the set of sounds produced by non-human animals, “geophony” which is the set of natural sounds but not biological origin – the sound of rain, wind, flowing water, surf… – and “anthropophony”, all human sounds.
What are the major questions that eco-acoustics researchers want to answer?
Ecoacoustics is at the beginning of its history. There are still a lot of technical issues to deal with. In particular, it is necessary to better estimate the biodiversity in the recordings made automatically. Several approaches are possible. One of them, which we proposed a few years ago, is not to identify the species constituting a soundscape but to work on a global scale. The degree of complexity of the sounds is estimated, revealing an ecological complexity. This technique is fast, inexpensive in terms of calculation and energy, but not very precise. We are now trying to go further by automatically identifying the species present using artificial intelligence techniques. It’s a real challenge because the sounds are very variable and overlap each other. There are apps that try to do this, but we are still far from what is possible with voice or music recognition.
⋙ These applications allow you to identify the species of a bird thanks to its song
Can we also estimate the state of environments, ecosystems, using sounds?
Much work currently focuses on this issue, particularly for monitoring the coral reef or tropical forests. It is a question of estimating to what extent these ecosystems are disturbed, simply by listening to them. A disturbed ecosystem tends to be less acoustically complex, or even silent.
And what does the sound aspect bring to, in a way, “take the pulse” of an ecosystem?
The advantage of eco-acoustics is to be able to “observe” in a completely passive way, that is to say without intervening in the ecosystem under study. We set up our tape recorders and let them observe for us. The second, major interest is that we record a lot and on several sites at the same time. We thus significantly increase what is called “sampling power”. The observation is not unique, it is almost continuous and on a large spatial scale. Finally, eco-acoustics makes it possible to build historical archives, to which we can return later. We are still working on sounds that we recorded 10 years ago! Data can also be shared very easily, because everything is digital.
Can we listen to the whole ecosystem, or only a part?
This is another advantage of automatic registration: it is not selective, but on the contrary generalist. Everything is captured: birds, insects, amphibians, or even, with hydrophones (underwater microphones, editor’s note), marine mammals, fish, crustaceans… We have been criticized for only monitoring the biodiversity that “sung”. Of course… but there are many species that “sing”! We therefore have a very wide angle of observation.
⋙ These singing lemurs have a sense of rhythm similar to humans
Does it make sense to speak of “animal music” (the exhibition to be discovered at the Philharmonie de Paris until January 29, 2023 is entitled “Musicanimale”)?
This is the big question of the exhibition (laughter). In scientific terms, animals are not musicians. They produce sounds to find prey, avoid a predator, reproduce, feed their young… In other words, for life and for survival. It’s very functional! Singing requires energy, and it is also taking risks by revealing oneself (to predators). In any case, it is not leisure.
And yet, it turns out that these sounds, especially those of birds, are pleasant to us: they give us pleasure. They allow you to recharge your batteries, to reconnect with nature. Why then not consider them as music? Perhaps not music in the usual sense, which is written (in the form of scores, editor’s note) and which follows historical precepts. Rather than classical or traditional music, the sounds of nature would be closer to “concrete music”, formed of sound units which are not necessarily notes – and which do not always follow a predefined rhythm. As long as these sounds give us the same sensations as music, we can consider them as such! Birds are not “musicians” strictly speaking, but they can become so to our ears.
Precisely, what are the animals that are most often considered as “musicians”?
The most “successful” ones are basically the birds. First, because their songs are accessible, even in town. Very intense, very fluty, rhythmic… and exactly in our auditory spectrum (the human ear perceives frequencies between 20 Hertz and 20,000 Hz, editor’s note). They are harmonic and harmonious for the most part! There has also been a strong craze for whale song, which has a slightly melancholic musicality. It was in the 70s that this musical value was revealed. Whale sounds also enter our hearing spectrum. They are soft, round, soothing, like whales. We also hear the echo of their habitat, these great oceans that fascinate us. Hence the fact that it is sometimes used for relaxation.
⋙ How Humpback Whales Sing the Same Song Thousands of Miles Apart
We’re not talking about music for insects, then?
Insect sounds apparently provide less pleasure. However, they are very diverse and very interesting scientifically, just as much as birds or whales. Unfortunately, the fall in insect biodiversity is accompanied by a sound impoverishment of forests and especially grasslands. An alp in summer without the chirping of insects loses enormous ecological and recreational value
Can we, moreover, document the decline of insects through sounds?
Yes, but it hasn’t been done yet! The heart of current research focuses on birds. It’s a real perceptual bias, linked to the fact that we have empathy for these animals. There is, obviously, a compassion for birds that does not exist for insects. Like a spider, an insect is often frightening: we kill it, we crush it, we silence it! Our team is starting to study insect populations using acoustics. We installed automatic tape recorders this summer in the Haut-Jura Regional Nature Park and in the Py Nature Reserve in the Pyrenees to monitor locusts and grasshoppers.
⋙ Why do the cicadas hardly ever sing anymore in August?
What results do you expect?
Our tape recorders are still recording, we don’t have the data. But it was extremely hot in the Jura and the Pyrenees – like everywhere in France this summer – and apparently the insects are very few. Unfortunately, I think we will hear this absence! We should be able to document and prove this effect of drought. This may be another way to raise awareness of the ecological consequences of climate change.
Raising awareness of the decline of biodiversity, is it the role of science, but also that of art?
Precisely, I think that the “Musicanimale” exhibition is a superb opportunity to bring science and art closer together to raise awareness among a wide audience. The exhibition is not limited to musical works. It presents plastic, graphic, sound and video works, all of which amaze and alert at the same time. It’s artistic diversity for biological diversity, and that’s very stimulating!
The exhibition “Musicanimale” is to be discovered at the Philharmonie de Paris until January 29, 2023. To find out more, see also “The Sound of the Earth: Radio Chronicles” by Jérôme Sueur, published in March 2022 by Actes Sud.
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