The glottis is the entrance to the larynx. These organs work together to give the frog its unique vocalizations and sounds. As the folds vibrate, they produce a buzzing sound. Those animals that can produce sounds using only the glottis, and don't have a larynx, are called glottal animals. It produces sound by creating friction.
Amphibians, reptiles and mammals have a glottis, which is also used in breathing and protecting the trachea against food that may get stuck in the throat.Learn more about Frogs