2. Phonation and animal hearing

2.1 Larynx, syrinx and the production of complex sounds

While Arthropods produce sound through friction and percussion, Vertebrates produce sound through a wind instrument, to use a musical analogy: air blown into the air sacs (lungs, air sacs in birds) is then modulated by membranes positioned in a tube (bronchi, trachea). In the first case, the sounds produced are simple, consisting of more or less rhythmic sound units with little frequency modulation. In the second case, due to the presence of specialized vocal organs, sounds can be much more complex.

In some reptiles, amphibians and mammals, the larynx is the vocal organ. In birds, the larynx lost its vocal function, supplanted by the syrinx probably between 66 and 68 million years ago