January 2, 2011

Complex Bird Songs Created With Simple Device

Researchers have developed a simple rubber device that is capable of replicating complex bird songs.

According to the researchers, a song can be produced by blowing air through the device, which mimics a bird's vocal tract.

The study challenges the theory that birds have to learn complicated neurological controls in order to produce distinctive cells.

The researchers plan to share their data with biologists to see if it sheds new light on how birds produce their music.

"I definitely did not think that I would be able to produce a whole bird song when we started," Aryesh Mukherjee, a member of the project team from Harvard University, explained to BBC News.

"We were just playing around and I probed the device in a certain way and it started playing a bird song - that was very exciting."

He said that the design of the device was rudimentary.

"It is made out of two pieces of rubber, which are stuck together but leaving a little area in the middle that forms the vocal tract."

The device is pressed together by a motor that replicates the action of a contracting muscle.

"In the terms of physics, the tract is just an elastic membrane of springs. If you tense it correctly, and probe it in a certain way, it starts vibrating," Mukherjee told BBC.

"Our project was to control the frequency of those vibrations."

The researchers were able to replicate a number of bird-songs, like Bengalese finches and vireos, and they were also able to model the song of zebra finches.

"Making it sound like a zebra finch is the holy grail of the project," Mukherjee said.

"We have been able to come pretty close to it, but we have been able to replicate other bird species much better."

He told BBC that the song of the zebra finch was a little more complex, so it will require some fine-tuning.

"But we are getting close," he added.

The discovery was made during a project with a goal to learn more about the physical behavior of vocal tracts.

"We were working with neuroscientists who were trying to understand how a bird learns to sing," he told BBC. "It was considered a very complicated process, and we tried to uncover some of the mysteries with physics."

Bird songs have been the subject of many studies.  Neuroscientists have shed light to how young birds learn songs from adult birds.

However, Mukherjee said the project's results showed that it was possible to replicate bird-song without high degrees of control inputs.

"By just having one muscle (motor pressing the device) in the equation, you can get a lot of sounds," he told BBC.

"Translating that back into the idea of neurological control... it suggests that the control needed to produce seemingly complex songs is not as challenging as previously thought."

Mukherjee said that whether this challenges current thinking on how birds produce their song was out of their expertise.

"We are in no position to make a claim about what this has to do with bio-physics or neurological control within birds. All we can say is what we have learned from our experiments, and share that information with biologists," he said.

Shreyas Madre, another member of the team, is developing a mathematical model to see if it is possible to identify some of the key principles in producing complex birdsong.


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