In the shadow of climate change challenges, a topic far less publicized than global warming could nonetheless generate significant attention. This concerns the sonic state of our planet, particularly the living world. Silence does not exist on Earth; noise is constantly present.
While sometimes a source of disturbance, noise is primarily a conveyor of information that is both surprising and diverse. Birds sing, waves lap, leaves rustle... nothing new under the sun, yet!
The development of Bioacoustics, notably initiated by Bernie Krause in the 1960s, has revealed the acoustic activity of thousands of animal species.
Beyond this sonic richness of the animal world, his work and that of his successors have demonstrated the extent to which human activities have damaged existing ecosystems.
Conceptualized by M. Schafer and B. Krause, among others, the notion of « soundscape » (which can be translated as « sonic landscapes ») encompasses sounds originating from abiotic elements—meaning any element not attributed to a living being, such as wind (geophony)—human-generated sonic activities (anthropophony), and sounds specific to flora and fauna (biophony).
The term « Anthropocene » first appeared in 2000 when American biologist Eugene F. Stoermer and chemist Josef Crutzen first referred to the Anthropocene as a new geological phase that would emerge with the onset of the 19th-century Industrial Revolution. For nearly 12,000 years, humans, as we know them, evolved during the Holocene epoch and were, from an acoustic perspective, part of a category embedded within biophony: Anthropophony (sounds of human origin).
With the emergence of humankind, the roles of geophony and biophony within the soundscape have shifted. Biophony is already remarkably rich, featuring a multitude of vocalizing living organisms. According to Q. Arnoux in his book Listening to the Anthropocene, « the initial relationship that human beings develop with soundscapes is one of adaptation, listening, and inspiration ».
Krause described the acoustic connections between the sonic emergence of the human species and existing soundscapes as: « The elaborate interactive process by which each animal voice found an available frequency or time slot certainly did not escape the methodical minds of our ancestors. It must have served as a model from which to arrange our own sounds, form our voices, and create our first instruments ».
Each vocalizing species (including humans) thus shares a very broad sound spectrum, far more extensive than the capabilities of the human ear. However, through its evolution, humanity began to create new sounds that no longer resulted from its own vocalization via an onomatopoeic system, as described by B. Krause, but rather from its broader activities. With language and music becoming a distinct acoustic identification for human beings, Anthropophony then emerged as a full-fledged component of the Earth's soundscape.
With the dawn of the Industrial Era and the constant modernist growth of Western civilizations, sounds of mechanical origin have become increasingly prevalent on Earth. This new acoustic production is not merely an additional component in the soundscape; it asserts itself through its intensity and duration, thereby masking numerous acoustic layers. The emergence of this new acoustic layer, often described as « noise pollution », is termed Technophony. Airplanes, trains, industries, mechanical tools, etc., form a sonic layer that, with human industrial growth, encroaches upon both Biophony and Anthropophony.
Issues related to noise pollution have only recently been incorporated into population protection measures. However, these considerations represent an anthropocentric view of noise pollution; every living organism is impacted by noise pollution through multiple effects.
Noise pollution, particularly due to its intensity, causes species present in an exposed environment to flee. When species do not flee, they must adapt to a new soundscape.
Consider the example of passerine birds exposed to high levels of road traffic noise; to survive in such an environment, they must increase their vocalization volume and extend the associated emission periods.
The consequence of this forced adaptation is an additional energy expenditure for the passerine, leading to premature exhaustion and, consequently, an accelerated decline in the population within that environment.
From an acoustic perspective, human activities do not solely emit frequencies audible to humans: submarine sonars emit ultrasounds that disrupt the communication of some cetaceans, road traffic noise impacts a large number of species across a broad spectrum also audible to humans, drilling activities emit numerous infrasounds, and so forth.
Pollution is therefore a concern for every living organism!
Colloquially, the study of biodiversity through the lens of sound is often referred to as bioacoustics. However, the subject is more complex, and it is crucial to distinguish between two concepts: bioacoustics and ecoacoustics.
Bioacoustics, which originated from the first bird recordings in L.K. Koch's works at the end of the 19th century, studies the sonic behavior of animal species, also known as biophony. It primarily focuses on analyzing recorded sound signals from animal species to decipher behavioral and social information about wildlife. This discipline has, moreover, evolved in parallel with technological advancements, particularly in computing.
The study of sound signals requires significant resources and material capabilities: microphones, storage, computational power, etc. This discipline is exclusively dedicated to analyzing an animal's sound signature and the information conveyed by the sound signal. It investigates the specific sonic mechanisms of various living organisms, particularly their resilience and adaptation to changing environmental conditions, including climate change.
Ecoacoustics, on the other hand, is a much more recent discipline, primarily initiated by the work of Bernie Krause. Unlike bioacoustics, which focuses on the individual study of a single species, ecoacoustics adopts a far more macroscopic perspective by recording and analyzing the sonic activity of an entire biome.
By performing a sonogram of an ecosystem recording, we can analyze the acoustic signature of the various species present in the environment. This method, previously conducted empirically, can now be achieved through « automation » using machine learning tools, thereby identifying all species present in one (or more) recording(s).
Ecoacoustics therefore considers sound as an integral component of an environment's characteristics, thereby becoming an environmental indicator for biodiversity monitoring.
In collective consciousness, we perceive climate change solely through the visual lens: ice caps are melting, floods are increasingly recurrent, storms are ever more devastating, and so forth.
But would climate change and biodiversity erosion also be audible? This is precisely where the significance of ecoacoustics lies.
The primary objective of this discipline is to characterize the acoustic richness of an environment, not at the individual level, but at the species or even species group level.
Current technologies now enable the capture of a broader sound spectrum than human hearing and the acquisition of tens of thousands of hours of recordings. All this information must then be analyzed, particularly through automated acoustic recognition, which allows for the identification of present species and their numbers.
Traditionally, ecologists conduct animal inventories at a given site once or twice a year, providing limited information on species behavior and their daily interactions. The data collected through recordings also allows for observing the impact of certain disturbances (particularly anthropogenic ones) on an environment.
The impact of anthropogenic noise is even becoming a physical factor of « ecological fragmentation », capable of decimating entire populations near noise sources, especially terrestrial transport routes.
Better evaluating and analyzing these soundscape modification phenomena would be beneficial for nature conservation strategies.
Similar to green and blue infrastructures in urban environments, 'white infrastructures' are being discussed by the Institute of Ecology and Environment of the City of Paris to establish silent ecological continuities and combat noise encroachment. The Ministry of Ecological and Solidarity Transition has also published a methodological guide on combating underwater noise; the identification and preservation of quiet zones are part of the Environmental Noise Prevention Plan (ENPP); and numerous other initiatives are taking shape.
A gradual awareness regarding noise pollution appears to be gaining traction, benefiting both humans and all living beings.
The spring lockdown of 2020 particularly demonstrated this: as silence appears to settle with reduced noise pollution, nature manages to express itself more vibrantly.
The challenges concerning our future soundscapes still require refinement, but the reduction of our polluting emissions, particularly noise, remains a key response for redefining our landscapes and combating climate change.
With proven consequences for health (sleep disturbance, stress, etc.) and the economy (productivity decline, real estate depreciation, etc.), ADEME estimates the social cost of noise at 147 billion euros per year in 2021.
Driven primarily by sustainable development, low-carbon, and societal challenges, timber constructions are proliferating in the design of new build and renovation projects across all sectors (housing, offices, hospitality, cultural). From an acoustic perspective, these new complexes in the French construction landscape raise several questions.