Natural sounds and human health
The sputtering of raindrops as they hit the ground, the melodies of chirping birds, and the whistling of the wind through grassy prairies are some of the sounds universally considered to be calming and associated with profound health benefits to human beings. Nature’s sonic environment is crucial for many reasons, including scientific appreciation, cultural heritage, and human beings’ physical and spiritual welfare.
According to Krause (2015), the significance of the sonic environment and natural soundscapes to humanity’s well-being emphasizes the need to appreciate and preserve the natural world which produces these sounds. Natural soundscapes are innately unique, especially in their collective state, as they represent an entire ecosystem’s voice (Aletta, Oberman & Kang, 2018). They embody the harmonies and melodies of nature.
Unfortunately, human activities are insidiously endangering and eliminating these natural ecosystems, resulting in a rapidly shrinking sonic environment. An intimate understanding of the sources of natural soundscapes can fundamentally improve human appreciation of the sonic environment, enabling a comprehensive evaluation of the environmental quality of parks, conservation zones, urban planning and design, and the preservation of these soundscapes for humanity to benefit from them.
The natural soundscape is a sublime blend of different concurrent sounds, which form the unique harmony of a specific habitat. According to Krause (2015), a soundscape has three main components: biophonic, geophonic, and anthropophonic sounds. These components inform exploration of the relationships between landscapes and the patterns of natural sounds (sonotopes).
The geophonic component of the soundscape includes the wide array of sounds arising from nonbiological natural sources like wind, sea waves, lightning, running water, rain, thunderstorms, floods, volcanoes, earthquakes, and avalanches. Typically, geophonies create the acoustic background which other sounds can overlay, mask, or blend with. The geophonic part of a soundscape is significantly impacted by the geomorphic attributes of the landscape, such as the steepness, expansiveness, and composition of the region. Moreover, geophonic qualities are defined by climatic conditions and local weather, making them unique to their location; no two locations have identical geophony.
Landscape structure, characterized by landforms like canyons, valleys, ridges, cliffs, and water bodies, inherently inspires the unique propagation of sounds and acoustic degradation. In terrestrial settings, the propagation of sound waves and their patterns are altered considerably by the intersection of breeze regimes, air pressure, humidity, and temperature. Similarly, sonic processes and patterns in marine settings are affected considerably by the unique balance of depth, salinity, and temperature (Farina, 2013). Therefore, the geophonic aspect of a soundscape emphasizes the relationship the sounds have with the landforms and the climatic environment, highlighting how they impact the quality of sound produced.
The biophonic aspect of a soundscape refers to the sounds emerging from nonhuman living organisms in a particular ecosystem. Naturally, every ecosystem and ecotope in that ecosystem has a unique and distinct biophony, dependent on the region’s unique population and composition of flora and fauna (Krause, 2015). Since the flora and fauna of a particular region are affected by the climate, there is an intricate relationship between the geophony and biophony that compounds the uniqueness of a soundscape.
In temperate terrestrial ecosystems, most biophony comes from birds, mammals, insects, and frogs, whereas the biophony of the tropical region is dominated by frogs and insects. Marine environments are divided into freshwater and seawater. The seawater setting is further classified as either deep or shallow waters, which have distinctly different sources of biophony. In freshwater biomes, insects and fish are the primary sources of sound, while crustaceans are the leading sources in shallow seawater environments. Finally, deep seawater biophony is dominated by cetaceans (whales, dolphins, and porpoises) (Farina, 2013).
In terrestrial settings, biophony is altered considerably by seasons, diurnal patterns, and latitudes. For example, vocal animals like birds and frogs are more active at particular times of day, such as dusk and dawn, emphasizing the role of diurnal patterns for these species. Further, some birds are mainly active in particular seasons, especially spring, and inactive during winter. Latitudes also affect biophony: most birds in intertropical regions are consistently active, while in high latitudes birds are mainly active during breeding seasons and otherwise silent. These factors fundamentally affect each other, with latitude and seasons interacting to produce unique biophonies (Smalley et al., 2022). For instance, in subtropical regions, the effect of latitude outweighs the impact of the seasons, as most animals are active throughout. Contrarily, the impact of seasons is profound in polar regions, as animals’ behavior and activity depend heavily on the seasons.
In marine environments, biophony relies on currents, sea depth, light penetration, and transparency. Generally, climatic changes can inspire seasonal changes, resulting in fundamental and long-term variations of vocal activity in a particular biome.
Biophony represents the acoustic activity of different animals as they strive to both actively and passively communicate within and without their species for various reasons, including breeding, safety, and community. Therefore, the biophonic component of the soundscape represents the unique communication channels that correspond with the intricate sonic settings of an environment. Typically, the intricacies of acoustic communication within the biophony rely on species-specific sonic activity, population concentration, season, species community size, period of time, and the morphology of the biome. Many of these factors rely heavily on the region’s geography, consequently emphasizing the intricate connection between geophony and biophony.
Biophonic complexity is encapsulated in acoustic diversity, which is recorded in frequencies. Acoustic diversity is increasingly being utilized to approximate the complexity of different habitats and biomes, and is representative of a unique assemblage of species. However, acoustic diversity cannot be associated with biological diversity, especially in birds, as they have a unique organ called the syrinx, which gives them acoustic versatility and plasticity by producing a wide range of sounds.
While human voices are a crucial element of biophony, the complexity and versatility of human acoustic expression referred to as voice is a natural oddity which demands in-depth analysis, resulting in its exclusion from the definition of biophony.
The anthropophonic aspect of the soundscape refers to the sounds produced by machines and devices such as horns, cars, trains, and airplanes. Globally, the anthropophonic component of the soundscape is increasingly dominating and interfering with different ecosystems and biomes. The increasing prevalence of anthropophony around the world is fundamentally connected with capitalism, urban development, and globalization. Anthropophony is not a natural element of soundscapes, despite being a significant part of the modern sonic environment.
Anthropophony is considered to be the world’s leading cause of noise pollution. Noise pollution has been associated with a constellation of insidious consequences for all organisms, and for human health. In the short term, noise pollution has been associated with increased aggression and indignation, stress, tinnitus, hearing loss, and insomnia. Long-term exposure can result in depression and cardiovascular diseases.
Shifting soundscapes in contemporary society
In the contemporary world, it is becoming apparent that anthropogenic influences on landscapes have resulted in environmental devastation, fragmentation, and pollution. Further anthropogenic influence has inspired the subtle but steady degradation of the acoustic environment, characterized by the increasing prevalence of anthropophony over biophony and geophony. Modern soundscapes show that natural sounds predominantly comprise biophony and geophony, while the artificial soundscape primarily comprises anthropophony. With the emergence of new technology and increasing urbanization, anthropophony is coming to dominate the soundscape.
While soundscapes are treasure troves of information about particular biomes, few have considered the coded secrets of life encrypted in acoustic environments and their effects on human welfare. Yet human health is fundamentally affected by the soundscape, particularly when the quality of sound degrades to noise. This disconnect between humanity and the benefits of soundscapes has arisen due to the increasing distractions of anthropophony and the disappearance of natural soundscapes due to human activity.
As humanity encroaches on natural ecosystems, the sonic environment is shrinking in the face of noise pollution. Urbanization and globalization are driving the increasing prevalence of anthropophony, while biophony and geophony are insidiously diminished. Soundscapes in contemporary society vary according to proximity to urban areas and industrial and transport infrastructures, including air corridors, highways, and airports. Typically, the sonic gradient in urban regions offers incredible insights into society’s social and economic contexts and values. However, as awareness of the significance of the voices of the wild grows, efforts are increasingly directed toward preserving the sonic environment, with a focus on the preservation of varied ecosystems.
The increasing ubiquity of the concept of sustainability has inspired parks and conservation zones to design settings in the urban world where the sonic environment emphasizes biophony over anthropophony (Buxton et al., 2021).
However, despite attempts to mitigate anthropogenic effects on the sonic environment, emerging patterns of environmental injustice are significantly degrading the quality of the solutions adopted. The sonic gradient in urban areas demonstrates the social and economic prejudice of most societies: in general, the areas with the worst sonic quality and noise pollution are predominantly home to the poor and to ethnic minorities. The preservation of the natural soundscape, therefore, demands that environmental justice be integrated into the strategies designed to conserve and rebuild the acoustic environment, such as ensuring that everyone, regardless of race, ethnicity, and religion, has access to parks and conservation zones.
Noise and human health
The effects of noise on human health create a fundamental basis towards understanding the effect of natural sounds on human well-being. The impact of anthropophonic noise pollution on human health is the dark underbelly of the positive effects of geophony and biophony on human health. Therefore, the exploration of noise pollution on human health offers insight into the intricate connection between the soundscape and human health. As the discipline of acoustic and soundscape ecology becomes more mainstream, studying the effects of noise on human health has gained popularity in the last decade.
Noise causes pervasive, long-lasting, and medically relevant impacts on human societies, as it affects communication, recreation, sleep, and concentration. Health and well-being are essential to an individual’s quality of life and are significantly impacted by ambient sonic noise. Typically, noise impacts health on a primary and secondary level. The World Health Organization outlines seven distinct classifications of detrimental health effects caused by noise, such as hearing impairment, cardiovascular issues, mental health issues, detrimental social behavior and annoyance, impaired task performance, and sleep disorders (Medvedev, Shepherd, & Hautus, 2015).
Hearing impairment is one of the main consequences of noise on human health, and is usually caused by other phenomena such as heredity, infection, ototoxic drugs, and trauma. Exposure to acoustic pressure above 85 decibels (dB) for eight hours increases the likelihood of hearing impairment. Generally, hearing impairment can be caused by exposure to high volumes over long hours, such as in schools or at work.
Children are considerably more susceptible to hearing impairment, which can progressively evolve into hearing loss if the duration of exposure is increased. Hearing impairment is typically accompanied by tinnitus, abnormal loudness perception (meaning a loss to the range of hearing), and paracusis (hearing impairment). However, while hearing impairment is the primary effect of noise on human health, it can cause several secondary effects, such as feelings of isolation, depression, loneliness, poor school or work performance, and speech impairments. In children below a particular age, noise can result in hearing loss accompanied by adverse effects on cognition, communication, social-emotional development, and academic performance.
Noise levels above 140 dB can cause permanent hearing loss. The second primary impact of noise on human well-being and health is upon communication. Generally, noise interferes with communication, which has profound effects on the individual’s behavior and attitude. The primary level of interference in communication results in a short concentration span, irritation, low self-esteem, fatigue, and stress. Therefore, disruptions in communication can detrimentally impact relationships between people, resulting in the dissolution of crucial support systems in the community.
Noise can also impact human health by interfering with patterns of sleep and sleep quality. Generally, acoustic pressure of over 30 dB is enough to disturb an individual’s sleep. Intermittent noise increases the likelihood of the individual being awakened. When one is asleep, noise affects different physiological functions, such as heart rate, pulse amplitude, blood pressure, and involuntary body movements. Therefore, exposure to noise during sleep results in the individual experiencing depression and a decline in daytime performance.
During sleep, low-frequency sounds are more detrimental than high-frequency or loud sounds. Noise can also have adverse effects on cardiovascular well-being, as it affects the endocrine system and the autonomic nervous system, generally increasing the individual’s susceptibility to cardiovascular diseases.
Further, noise fundamentally impacts the mental health of the individual as it intensifies several mental conditions, such as stress, anxiety, nausea, headache, psychosis, and hysteria. Buxton et al. (2021) highlight that noise affects the performance of tasks, as it affects the individual’s cognition, concentration span, and motivation. Finally, noise inspires negative social behavior and increased aggression. Typically, low-frequency vibrations are associated with a wide range of negative emotions, including anger, dissatisfaction, depression, helplessness, and agitation.
Natural sounds and human health and well-being
Natural soundscapes are widely associated with a wide array of health benefits, from stress relief to feelings of tranquility. People have been aware of the beneficial impacts of natural sounds on human health from ancient times (Bentley et al., 2022). Ancient communities such as the Aztecs, Greeks, and Chinese illustrated their awareness of the significance of natural sound on human welfare through their mythologies and legends. The intricate connection between health and natural soundscapes is emphasized by the ancient societies which lived closely with the natural world, particularly communities that leveraged the biophonies and geophonies of their environments as a spiritual and healing voice. Some human communities, such as the Ba’Aka in the Central African Republic and Congo, continue to leverage the biophonies and geophones of the rainforest to alleviate a wide range of maladies (Sarno & Krause, 1995).
Natural soundscapes comprising biophony and geophony create a symphony that has profound effects on human beings’ health and well-being. Different sounds have been associated with varying impacts on well-being: for instance, geophonies comprising sounds of moving water or raindrops have been associated with resolving issues such as insomnia and relieving stress (Smalley et al., 2022).
Natural soundscapes have various physiological effects on the human body when an individual is asleep. In a state of rapid eye movement sleep (REM sleep), a particular frequency of natural soundscapes can maintain and calm an individual’s blood pressure, heart rate, pulse amplitude, and respiration, and considerably reduce involuntary body movements. Generally, these physiological responses to natural sounds cause liveliness, animation, and improved performance (Qiu & Zhang, 2021). However, these benefits can be achieved during wakefulness through mindful listening.
Mindful listening involves immersive and complete focus on what is being listened to, by giving it absolute attention. Mindful listening to immersive natural soundscapes, such as trickling water or the soughing of wind through trees, has numerous benefits to the individual. In addition to curing insomnia, mindful listening to a natural landscape can profoundly improve mental health. Mindfully listening to soundscapes has been associated with an overall reduction in stress, anxiety, nervousness, and social conflicts.
Natural soundscapes create a sense of calm and tranquility which has potential for stress relief and the elimination of anxiety (Alvarsson, Wiens, & Nilsson, 2010). Even recordings of natural sounds can play a major role in reducing anxiety and stress. Van den Bosch et al. (2017) state that medical professionals are currently exploring the potential of natural soundscapes in relieving symptomatic disorders such as asthma, ADHD, allergies, hypertension, tinnitus, stress, and hypertension. Shinrin-yoku (also known as ‘forest bathing’) is a type of healing in Japanese medicine that literally translates to “taking in the forest atmosphere”. Japan and South Korea emphasize the health benefits of spending time in a living forest, including its biophonies and geophonies (Tsunetsugu, Park, & Miyazaki, 2010).
Humanity is therefore becoming increasingly aware of the role of soundscapes and their potential to improve human health and well-being. Aside from health benefits, listening to natural soundscapes has been associated with mood improvement. The sense of tranquility that accompanies mindful listening to natural soundscapes is akin to meditation and is characterized by an overall reduction of aggression, agitation, and annoyance (Farina, 2013). As a result, natural soundscapes are critical to the overall health and well-being of the individual by mitigating a plethora of pathologies and improving the individual’s mood.
The sonic environment refers to the intersection and interactions between the physical attributes of sound, landscape, and ecosystems, as well as to the social and cultural interpretations of these relationships. The sonic environment fundamentally affects human health, well-being, and spiritual welfare. Analyzing the sources of soundscapes aids in establishing their uniqueness and highlights their effects on humanity.
An intimate understanding of the sources of natural soundscapes can radically improve human appreciation of the sonic environment, enabling the comprehensive evaluation of the environmental quality of parks, conservation zones, urban planning and design, and the preservation of these soundscapes to allow humanity to benefit from them.
Soundscapes include biophonic, geophonic, and anthropophonic elements, which affect human health in different ways. Anthropophonic soundscapes predominantly contribute to noise pollution, which is detrimental to human health, while the biophonies and geophonies which form natural soundscapes have positive impacts on human health and well-being.
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Tsunetsugu, Y., Park, B. J., & Miyazaki, Y. (2010). Trends in research related to “Shinrin-yoku”(taking in the forest atmosphere or forest bathing) in Japan. Environmental health and preventive medicine, 15(1), 27-37.
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van den Bosch, K. A., Andringa, T. C., Peterson, W., Ruijssenaars, W. A., & Vlaskamp, C. (2017). A comparison of natural and non-natural soundscapes on people with severe or profound intellectual and multiple disabilities. Journal of intellectual & developmental disability, 42(3), 301-307.
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