Engineers mimic birdsong with stretchy rubber tube
Harvard University researchers have created a simple device capable of perfectly mimicking complex birdsongs by blowing air through a stretched rubber tube.
Bird song is an indicator of fitness and health and vital for sexual selection. Some birds, such as mynas, are excellent mimics, while others engage in courtship duets and some produce complex musical vocalisations.
For many years, researchers assumed that songbirds rely on complex neurological controls in order to produce their song. However, research led by Professor Lakshminarayanan Mahadevan, of Harvard’s John A Paulson School of Engineering and Applied Sciences could suggest that the birdsong has a simpler origin.
Research conducted by Professor Mahadevan and his team suggests that birds may use the properties of a soft material to produce and control their song. As air moves through the vocal tract, muscles surrounding the syrinx – the highly specialised organ used by birds to create birdsong – cause vibrations.
The researchers broke down the songs of the birds into a set of biomechanical and control tasks, finding that the complexity of the song could be the result of a simple instability in the structure of the syrinx.
This instability could be controllable under lab conditions with a bit of mathematical modelling.
“Our study adds to the growing realisation that physical instabilities with rich nonlinear dynamics, when coupled to relatively simple control mechanisms, may provide a mechanism for birds to begin to create complex behaviour by taking advantage of their physical, material nature,” said Professor Mahadevan.
In order to test how controllable this musical instability was, the researchers created an artificial syrinx from a rubber tube, and, using a mathematical model, successfully recreated birdsong from various species, including those of zebra finches and Bengalese finches.