Birds' surprising sound source

The best place for a bird's voice box is low in the airway

Date: April 10, 2019

Source: University of Utah

All air-breathing vertebrates have a larynx -- a structure of muscles and folds that protects the trachea and, in many animals, vibrates and modulates to produce a stunning array of sounds.

But birds, although they have larynges (plural of larynx), use a different organ to sing. It's low in the airway, down where the trachea branches to head off toward the two lungs. Called a syrinx, it's a uniquely avian feature. For decades, scientists, including those at the University of Utah, have been asking why the syrinx exists -- and how it developed in the first place.

Now, a team that brings together physics, biology, computation and engineering finds that the syrinx confers an advantage: by sitting so low in the airway, the syrinx can produce sound with very high efficiency. Their results are published in PLOS Biology.

"I'm always excited when something is counter-intuitive," says Ingo Titze, director of the National Center for Voice and Speech at the University of Utah and a co-author of the study. "Most people would say 'Put the sound source right by the mouth or the beak, and you'll get the sound to the listener.' But that's not what we're finding."

Read on