Birds' vocal cords are fastest known muscles

From National Geographic News:

Experts have long wondered whether bird song is caused by passive interactions as air moves between the vocal muscles or direct neuromuscular control.

"I had been looking at the muscles in a pigeon species and was amazed by how fast they were moving," said lead study author Coen Elemans at the University of Utah in Salt Lake City.

"[Pigeons] have really boring, slow songs, and it made me wonder what the muscles in songbirds were like, so I decided to find out."

What Elemans and colleagues discovered is that zebra finches and European starlings can change their tunes at frequencies as high as 250 hertz via direct muscle control.

This means that they are moving their muscles a hundred times faster than a blink of the human eye.

The research appeared on PLoS One on July 9, "Superfast Vocal Muscles Control Song Production in Songbirds," and the abstract begins:

Birdsong is a widely used model for vocal learning and human speech, which exhibits high temporal and acoustic diversity. Rapid acoustic modulations are thought to arise from the vocal organ, the syrinx, by passive interactions between the two independent sound generators or intrinsic nonlinear dynamics of sound generating structures. Additionally, direct neuromuscular control could produce such rapid and precisely timed acoustic features if syringeal muscles exhibit rare superfast muscle contractile kinetics. However, no direct evidence exists that avian vocal muscles can produce modulations at such high rates. Here, we show...

Click on the PLoS link for the interesting details.