Sweet Inspiration
Vocal cords normally make noise as their owner breathes out, which means that when singers run out of air they have to pause to breathe in. Now, biologists at the University of Utah have discovered the inspiring technique some birds use to sing without stopping.
Franz Goller and Monica Daley carefully inserted pressure-measuring probes into the airways of zebra finches Taeniopygia guttata and recorded airflow changes during bouts of singing.
Zebra finch song typically consists of between three and seven syllables, separated by silent pauses for air called 'minibreaths'. These minibreaths were recorded as reversals of normal airflow, corresponding to short breaks in singing. But as well as observing sound production during breathing out (expiratiory phonation), the researchers found something entirely new: the birds could sing and breathe in at the same time.
To investigate this Ôinspiratory phonationÕ further, Goller and Daley used editing software to produce new versions of zebra finch songs, with the positions of certain expiratory and inspiratory syllables swapped around. They then played these songs to young finches who were in the process of learning to sing. Zebra finches donÕt start life with their adult song pre-programmed: they learn by copying the songs around them. It was found that the young finches could incorporate the artificially swapped syllables into their songs, and, importantly, that inserted inspiratory notes appeared as inspiratory phonation rather than reproductions in the form of normal expiratory notes.
importantly, that they performed inspiratory notes where expected, rather than simply reproducing the inserted syllables as normal expiratory notes. This suggests that the two types of sound production really are completely unique.
importantly, that inserted inspiratory notes appeared as inspiratory phonation rather than reproductions in the form of normal expiratory notes. This suggests that the two types of sound production really are completely unique.
a whole new dimension to birdsong
(Proceedings of the Royal Society of London B, vol. 268, pp2301-05)
Richard Northover
This is not Ôcircular breathingÕ, where a didgeridoo or flute player continues to push air out of their mouth while taking a quick breath. ÔInspiratory phonationÕ involves the vocal cords vibrating while air pushes past them backwards - the way most people do a donkey impression.