Zebra finches, beware! That tweeting noise you’re responding to might not be coming from another finch at all, but from a rubber tube-based bird-call-imitating device. The gizmo was devised by a team of physicists at Harvard University in an effort to understand the physics of bird song.
Neuroscientists have studied bird song for a long time, with an eye (or ear) towards the complex neurological changes that young birds presumably undergo in order for them to be able to produce such intricate noises. Harvard grad student Aryesh Mukherjee, however, believes that neural control doesn’t play as large a part as has been assumed – instead, he suspects that it’s the physics of the bird’s vocal tracts that are largely responsible.
Along with colleagues working in the lab of Prof. L. Mahadevan, Mukherjee created a device that duplicates those physics. It consists of an air source that pumps air through a stretched 2.5 cm x 2.5 mm rubber tube, which is modeled after a bird’s vocal tract. A linear motor presses on the tube, in the same way that a contracting muscle would perform in a bird.
The resulting sounds have been analyzed on a spectrogram, and were found to closely match the song of the zebra finch. Another researcher, Shreyas Mandre, has built a mathematical computer model based on the principles exhibited by the device. Using this model, which represents the voice as a stretched string with dampened vibrations, he has created digital finch calls that are also very realistic.
Mukherjee and Mandre believe that their digital model could be tweaked to mimic a variety of bird species.