My most recent travel was in August 2008, a three-week-long trip into the protected area of the Dzanga Sangha Dense Forest Reserve in southern Central African Republic, on the border with Congo and Cameroon. In the image above, I am recording from the mirador of the Bai Dzanga saline.
Sounds of the Bai Dzanga saline
I had made an earlier trip in 2002, planned in collaboration with Greenpeace, to the Rio Jauperì in the Amazon. I'm now planning a third trip to East Borneo.
I make these trips to do field recordings. I record sounds on site in the rainforest with experimental 3D microphones capable of capturing the entire spatial field. I present the sounds as documentaries, eco-acoustic compositions, and environmental sound-art installations for music venues, contemporary art galleries, and museums. I also produce CDs.
My goal in these trips is to explore, document, and communicate in sound the organic equilibrium and intrinsic beauty in the ecosystems of the world's areas of primary equatorial rainforest. It is along the equator where the most ancient and diverse ecosystems still thrive today in primary rainforests, where days are equal to nights year round and where natural rhythms and circadian cycles are the most regular and in balance.
The Dzanga Sangha Reserve is a remote location. I arrived by joining a film crew that hired a propeller plane that they flew from the country's only airport in the capital of Bangui to the airstrip of Bayanga, a village near the Reserve. Our journey spanned 500 kilometers in a spectacular low-altitude flight above the forest. Lavinia Currier, the film's director, was doing preliminary shooting for a documentary on the region's groups of Bayaka Pygmies. The production troupe's assistance during the first week of my time in Dzanga Sangha was essential for the logistical planning of my fieldwork.
Arrival by air
The Reserve, along with two research camps, Bai Dzanga and Bai Hokou, between one and two hours apart by Jeep, are managed by the World Wildlife Fund. I was able to work from both research camps, staying for about two weeks at Bai Hokou, where New Zealand researchers Gavin and Andrea Reynolds helped me in solving numerous problems related to the recordings, in particular humidity and electricity. From my base in the camps, I moved outside of the camps through different forest areas to record. With the help of Wildlife Conservation Society researcher Andrea Turkalo, I could ascertain which of the park's forest areas were primary, that is, never logged or exploited in any way. That important information let me be sure that my recordings were made within an intact habitat, making possible an audio portrait of the original ecosystem.
Recording in the Bai Hokou Saline
Sounds from the Bai Hokou Saline
At first, I traveled with a group, usually a couple of Bantu park guards and two or three Pygmy trackers. The group left the camp twice a day to track the movements of a family of gorillas. We hiked over elephant paths, which are the only practicable pathways in the dense forest. After the first few days, though, I began to work independently with Mbanda, a very small Bayaka man who had been recommended by the WWF researchers and with whom I felt very safe. Mbanda, a Pygmy tracker, understood exactly what soundscapes I was looking for and guided me through the forest and saline clearings during the twelve daylight hours.
Bai Dzangha forest
Bai Dzangha swamp
The camp was physically an area delimited by a so-called elephant fence. After dusk, due to the danger of elephant groups moving towards the clearings, it was not possible to leave the camp. Consequently, since I couldn't record manually at night, we built an autonomous system in the form of a box, to be suspended from a tree, that would contain the recording devices and also serve as an umbrella for the microphones in case of rain. To do that, we had to engineer a custom battery system capable of driving the recording gear for hours, as the only available power sources were solar panels. After several days of experiments and failures, we succeeded. The final recording was a full 12-hour sound portrait of an entire night on a forest border's swamp. No monkey could climb the rope (or more likely, no monkey chose to climb the rope), and all the recorders and hard-drives came back home!
Hanging the recorder in a tree
Bringing it down in the morning
Sounds of the Bai Hokou Forest
My idea had been to carry out as many recordings as possible throughout day and night in order to reconstruct an entire circadian cycle. My aim was to do this in different formats: a 24-hour real-time documentary; a one-hour, proportionally and chronologically accurate time-lapse reconstruction of the sonic ecosystem; and a 24-minute eco-acoustic composition. The recordings were also intended to preserve evidence of bio-diversity that would foster further research on the dynamics of species ensembles in old-growth habitats. All of this was accomplished. In total, during the trip, I was able to produce sixty hours of four-channel high-definition 3D material. And from a musical viewpoint, these integrated ecological systems, which manifest the maximum efficiency and coexistence of diversity, can be understood from a new perspective as organized sound.
In fact, in a rainforest the dense vegetation inhibits sight and everything is communicated through sound. Sound becomes the immediate reference for orientation and for the perception of distance and perspective. The Pygmies have an incredible capacity for listening and interpreting every acoustic signal and subtle change in the soundscape. As a musician, I was most enchanted by the incredible diversity of sounds and their emergent order, which one perceives instantly. Each species shares the soundscape through a process that is called 'niche segregation', which is to say that every new sound is produced within a vacant frequency space. In other words, the acoustic space of the rainforest is shared by its inhabitants.
While analyzing the recording of an ensemble of amphibians and insects at dusk on the Bai Hokou saline, I discovered that one species of bat, which echo-locates in an audible range, occupies the only free frequency bandwidth in the spectrum. This is an extraordinary example of niche segregation, in which the species adapts its behavior to its acoustic environment by finding a bandwidth with very little energy and specializing in echolocation within just this small, free range.
Elephants provide a different example. While we hear the higher spectral components of their sounds in open spaces, in the dense forest those higher frequencies are absorbed by the vegetation and tree trunks. Consequently, elephant groups communicate through low frequencies which, because they have longer wavelengths that are diffracted, are able to travel for longer distances, allowing elephants to communicate over several kilometers of impenetrable forest.
One night I had a strange experience that revealed some new concepts about niche segregation. I was awakened one night at about 2am by a massive broad-band sound coming from the creek below the camp. I tried to identify the species that could have produced such an intense and persistent sound. But the reverberation in the high-canopy forest made it impossible to hear the source of the sound, and I could not venture out of the camp because of our concern for animal movement at night. The sound contained intensity cycles of 2–3 minutes that seemed to come from different directions in the space before me. Then, as I prepared the system to record the sound from my location, the sound suddenly stopped, leaving the acoustic space completely silent. After five minutes, it began again, but this time, listening carefully to the onset of the cycle, I was able to identify the sounds. They came from various groups of different frog species located in adjacent sectors of the saline. Instead of niche segregation, they were competing for the same acoustic space, using sound pressure to overcome each other's group. It was an impressive wave of sound. I was witnessing a new phenomenon. And it was one of the most interesting, and frightening, sounds that I've heard.