If you sing or act or play a wind instrument, or if you have had training in those disciplines in the past, you have heard countless times about the importance of diaphragmatic breathing for sound production.
So this time of year, when earsplitting frog music emanates from every tiny pond and wetland, it is baffling to consider that frogs do not have diaphragms, or for that matter, ribcages.
Instead of using a diaphragm to draw air into its lungs, a frog lowers the floor of its mouth, which causes the throat to expand and the nostrils to open, drawing air into the mouth.
Then the nostrils close.
To sing, the male frog forces the trapped air between his lungs and mouth.
The air produces sound vibrations as it passes through the vocal chords, but the sounds are amplified by the puffed out vocal sac - sort of a pocket on the floor of the mouth which acts as a resonator.
Biologists describe the result as “acoustic conspicuousness.”
When the frog exhales, the vocal sac looks like a deflated bagpipe.
But an amorous male just re-inflates and peeps or croaks some more.
When a female frog hears the male chorus - if she detects the unique song of her species and if she is in the breeding condition - she selects the most desirable male and initiates courtship.
What makes the peep or quack or croak of one frog more desirable than another? Duration or pitch? Volume? Overtones? Stamina?
I have no idea, but apparently a female frog knows.
