Frog Songs

Some frogs, like this Squirrel Treefrog (Hyla squirrela) have vocal pouches that vary in size and stretch like balloons. These sacs serve as a resonating chamber, allowing the frogs to SING!
Male frogs vocalize by squeezing their lungs with their nostrils and mouth shut. Air flows over their vocal chords and into their vocal sacs blowing it up like a bubble gum balloon! (Photo courtesy of Chris Harrison)
Other frogs can make noises without such a sac.

For some species of frogs, only the males sing. Other types of frogs appear to have both male and female calls.
Large frogs have DEEP voices, meaning they call at a low frequency.
Small frogs sing in high chirps, meaning they call at a high frequency.
Cold frogs repeat their calls at a slower rate because the muscles controlling the sounds slow down!
Why do frogs sing? Well...it's actually for a variety of reasons!
Sometimes, frogs sing when they are trying to attract a mate. "HEY! Baby!"
Sometimes, frogs sing to mark their territory. "This is MY Lilypad!"
Sometimes, frogs sing becasue they know the weather is going to change. "Rain!!!"
Sometimes, frogs squeek when they are frightened or hurt. "Ouch! Eek!"