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Singing like a canary



The following is a summary of an article in Physical Review Letters  -
considered the most prestigious journal in our field.

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Singing Like a Canary

Singing like a canary requires little thought, but simple actions, to yield
complex vocal physics, researchers have found, yielding potential insights
into how humans generate speech sounds.
Human speech and the songs of many bird species share a central similarity:
the skills are not present at birth, but are only learned through early-life
experiences. 
To determine how brain activity leads to the production of sound, scientists
strive to understand how much of the sound comes from complicated
instructions from the brain and how much comes from complex physics of vocal
organs. 
Now, a US-Argentina research collaboration (Gabriel Mindlin, University of
Buenos Aires, Gabriel@birkhoff.df.uba.ar) has designed a simple physical
model that accurately reproduces notes of a canary song.
The researchers modeled the canary's vocal organ, called the syrinx.
According to previous experimental evidence, the syrinx generates sound
through vibrations of its labial "folds"---flaps of tissue which open and
close the air passage between the throat and the lungs.
In their model, the researchers make the key assumption that these labial
folds behave like a simple spring, moving back and forth to change the size
of the air passage. They further assume that a canary controls its
vocalizations through two actions: changing the pressure of the air from the
lungs and using muscles to modify the stiffness of the folds.
By varying these two parameters, the researchers found that the spring-like
labia could produce faithful recreations of three canary notes. Therefore,
simple changes to a basic system, rather than sophisticated instructions
from the brain, can reproduce the rich, complex vocal physics which give
rise to complicated sounds. (Gardner et al., Physical Review Letters, 12
November 2001.)


Russell Roberson
Durham NC
919-489-4888