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The sound of pollution

– Sounds can be beautiful, like the bioacoustics sounds produced in the Amazon Rainforest where animals, emulating musicians, perform independent parts and make specific voices that complement each other forming a glorious symphony. Or the installation “Sounds of the Earth”, by Doug Aitken, where you can hear the bowels of the Earth live in Inhotim, Minas Gerais.

Unfortunately, not only beauty comes from sound, but great distress and pollution as well. In Rio de Janeiro at least sixty percent of the complaints received by the Municipal Commission for the Environment (SMAC) are related to unwanted noise.

The cacophony of noises coming from machines in Rio includes buses, construction sites, trucks, motorcycles, people screaming and the infamous noises produced by the “makitas”, the power saws that are omnipresent in every neighborhood of Rio. Operators of these tile-cutting machines practically cut everything with it, including rock, concrete, copper and PVC pipes, and even wood.

Helicopters taking tourists to the top of Corcovado, the granite “hunchback” with the giant statue of Jesus, are another good example of unwanted noise. Neighbors have to constantly hear the repetitive and invasive sound of helices and turbines oscillating during the seven-minute joyride taken by tourists.

According to WHO (World Health Organization), noises above 85 decibels can compromise the auditory system if exposure is persistant for long periods of time, what happens in many work place scenarios. Academic studies also indicate that people exposed to excessive noise are more prone to heart attacks than those living in silent environments.

According to Juan E. Cruz, from Forensic Audio Arts Research Technology and Science, “all life depends on being able to hear infra/ultra sonic frequencies”. Cruz goes on to explain how animals need sound to communicate in order to find mates, locate territories, food and water. Hippopotamus, for example, not only use echolocation to find their way underwater but the also use infrasound, or very low frequencies that cannot be heard by humans, to establish mating.

Human noise can change the structures of animal and plant communities in wilderness areas. The study of soundscape ecology indicates that pollinating and seed disseminating animals rely on sound to properly distribute flora in natural ecosystems. Such areas can house megafauna or keystone species such as jaguars and anteaters, critical in maintaining the overall structure of ecological communities.

The biota can change even further from the sound pollution when certain plants spread due to lack of predators. Such plants can release allelopathic compounds that can suppress other essential plants critical in the stability of wilderness areas.

Oceans have also become a noisy environment for animals, such as cetaceans. This past Carnival, Rio de Janeiro’s port had the most numerous cruise ships docked in the world. Rio de Janeiro coastline is also saturated with cargo, container and petroleum ships that dot their way across the Guanabara Bay and some of the most popular beaches, such as Copacabana and Ipanema.

Ships can actually make quieter propellers and insulate their engine rooms to reduce drastically the impact on wildlife in the oceans.

Marcelo Szpilman, ocean biologist and director of Instituto Ecológico Aqualung, explained that sound waves affect the communication among whales and dolphins, which causes problems in locating the individuals of the same group or different groups.

Whales and dolphins, whose complex communication auditory capabilities are beyond ours, are exposed to booms from air guns used by the petroleum industry to locate hydrocarbons on the ocean floor. Military exercises using sonar blasts across the globe and the drone created by recreational and commercial ships also add to the increasing ocean sound pollution problem.

Noise has a bigger impact on life than most people realize. Audio forensics used in detecting sound pollution needs to be enforced in Brazil and in the world. Maybe we should trade our weapons for decibels guns, and aim at bigger problems like the sounds that are killing us softly.


Alfonso Stefanini has an MA in International Environmental Policy from the Monterey Institute of International Studies in California and a BA from Hampshire College. Alfonso lives in Rio de Janeiro, and he can be reached at:

Editorial Notes: Tourist helicopters taking flight in Rio, photo by ozziebackpacker/Flickr Creative Commons License.

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