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Article: Seeing Bird Songs
- Article from:
- The Washington Post
- Article date:
- September 13, 1987
- Author:
CopyrightThis material is published under license from the Washington Post. All inquiries regarding rights should be directed to the Washington Post. (Hide copyright information)
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IN THE 1950s, Bell Laboratories developed a machine called a
sound spectrograph for the analysis of the human voice. The device
quickly came to the attention of wildlife biologists-and particularly
ornithologists-who were interested in using it to analyze animal
sounds and calls.
Although we may hear such sounds as a single tone, they actually
consist of a combination of numerous separate pitches. The sound
spectrograph contains a bank of frequency filters, each of which
responds to a specific range. It breaks down incoming sounds into
their frequency components. A stylus responds to the various signals
and makes marks on a strip of paper, drawing a "contour map" of the
sound. Frequency ...