Until recently, recording animal sounds was strictly for the birds. But now, more listeners are relishing the sounds of nature on a batch of new CDs.
Launched about 1950, bioacoustics is a branch of zoology that studies the way animals listen to and make sounds. As recording techniques improved, the science grew and also attracted fans among general listeners, not just specialists.
Gianni Pavan, an Italian bioacoustician who is chairman of the Copenhagen-based International Bioacoustic Council, explains that there are two main categories of CDs: scientific collections of sounds (birds, frogs, insects, marine mammals) and New Age CDs with a mixture of music and natural sounds. Interest in both has grown in the last 10 years "to match an increased scientific interest and the need to discover nature."
Jack Bradbury, director of the Cornell University Laboratory of Ornithology's Macaulay Library, agrees that popular demand for nature CDs is now at an all-time high.
Perhaps an even greater stimulus, Dr. Bradbury adds, is "the incredible increase in the number of amateur birders throughout the world and particularly in the United States.... Since many birds are shy and only detected when they sing or call, having a resource to identify those species that you heard but could not see has become essential to many birders."
Fortunately, recording techniques have kept up with the demand, conquering some of the real difficulties of capturing elusive nature sounds. Axel Michelsen, director of the Danish Centre for Sound Communication at Odense University (Denmark) explains that the "dynamic range of modern digital instruments is much larger than that of old tape recorders. However, outdoor recordings are often made difficult by noises from wind or other sources (which we tend to ignore when listening outdoors, but which are very disturbing on a CD listened to at home)."
Douglas Nelson, director of the Borror Laboratory of Bioacoustics at Ohio State University, says that nature recording "takes patience, the right equipment, and knowledge of the animal."
Nowadays, most people use digital recorders. With the right equipment, it then becomes a matter of spending weeks studying the animals, learning how to get close enough to make the recording without disturbing them. "It basically requires hunting skills without the gun," he says.
But why do the scientists go to such pains to capture these sounds?
Mr. Pavan says that scientists and zoologists want to learn how animals have adapted to the acoustic features of their environments and used these conditions to communicate effectively with one another.
Bradbury notes that every animal "has to contend with ambient noise, distortion as the signal moves from one animal to the other, the risk of being overheard by a predator, and the need to encode different kinds of information in different signals."
He says that scientists want to understand how particular animals have solved these problems and to see if nature's solutions can be applied to human situations. The most famous example of this adaptation for human use is sonar, first used by bats and porpoises.
Yet even hardened scientists can take simple pleasure in the sounds while collecting data useful to prove their hypotheses. Dr. Nelson observes, "Both scientists and amateurs can enjoy animal sounds because they can be very beautiful, in some cases [even] strange."
Pavan says he particularly likes sounds of killer whales recorded close to the Pacific Coast of Canada. "The vicinity of the coast produces reverbs and echoes which greatly enrich the whales' sounds, giving them an astonishing cathedral effect."
But Pavan warns listeners, "Some new-age CDs are contaminated by 'nature sounds' generated electronically," which he and other researchers consider inferior to the real thing.
Mr. Michelsen was fascinated by animal calls recorded by a Slovenian colleague in the jungle of Borneo, mainly because it was impossible to guess (even for trained zoologists) whether the calls were from frogs, birds, or insects.
At home in one's own backyard, a listener has a pretty good idea of which sounds belongs to a particular group of animals, but this expectation may be misleading in other parts of the world, Michelson says.
Bradbury singles out a Cornell CD, "The Diversity of Animal Sounds," which includes the complex tappings of a treehopper insect and other animals: "I am personally touched by the echoing wail of the loon, another cut on this CD. It is a sound unlike any other in the world and is specifically designed to travel long distances over the water where these birds call."
The keyword is diversity, a wide range of approaches to solving life's problems through the use of sound.
As Bradbury says, "For the layperson, that diversity constitutes a recurrent reason for another daily hike and for the scientist it provides a career of puzzle-solving. For both, you never know what you are going to hear next and that greatly enriches the lives of all of us."
Recommended CDs of nature sounds
Voices of the Cloud Forest
Cornell Lab of Ornithology
Presented as "a day in Costa Rica's Monteverde Cloud Forest Preserve," this disc includes crickets, frogs, mottled owls, and howler monkeys.
The Diversity of Animal Sounds
Macaulay Library of Natural Sounds
A "greatest hits" compilation of sounds by whales, birds, lions, monkeys, elk, wolves, elephants, insects, and frogs, along with a 28-page booklet. http://birds.cornell.edu
Wild Britain: Sound Portraits from Britain's Wild Places
British Library. National Sound Archive
National Sound Archive Nsacd 9
(Isbn 9780712305136 )
A day in the life of the Amazon rainforest, with monkeys, insects, frogs, an afternoon rainstorm, and a chorus of birds after the storm.
African Bird Sound Vols. 1 & 2 /15 CDs
British Library National Sound Archive
A huge collection of 3,200 recordings.