Stretched rubber tube device mimics zebra finch songs

Monday, November 22, 2010

WASHINGTON - Harvard scientists have has reproduced many of the characteristics of real bird song with a simple physical model made of a rubber tube.

“We wanted to know if you [could] build a simple device, which has minimal control but reproduces some non-trivial aspects of bird song,” says L Mahadevan, a professor at Harvard.

Aryesh Mukherjee, of the Mahadevan’s laboratory, has made the bird call device consisting of an air source, which creates a flow through a stretched rubber tube (modeled after a bird’s vocal tract), and a linear motor that presses on the tube in a fashion analogous to a contracting muscle.

“Using this very simple device that pokes a tube, I see these beautiful sounds being produced without a sophisticated controller,” said Mukherjee.

When analysed on a spectrogram, the harmonics and other characteristics of the sounds made by the physical model closely resemble the songs of a zebra finch.

Shreyas Mandre, another researcher in the lab, is building mathematical models that seek to capture some of the underlying principles. His model, which represents the voice as a stretched string with dampened vibrations, creates digital birdcalls that are also very similar to the real thing.

The principles underlying the models aren’t limited to single species of birds. The researchers believe that-with a few tweaks-their models could mimic a variety of birdcalls.

The work was presented at the American Physical Society Division of Fluid Dynamics meeting in Long Beach. (ANI)

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