Tree crickets, though quite small, have a loud call that is sometimes mistaken for a cicada or tree frog. They cleverly amplify their trill by positioning themselves in a hole chewed in a leaf, with their tegmina aligned with the surface of the leaf. The leaf then acts as a speaker by significantly increasing the area from which the sound radiates. This is the same principle used by the speaker in your stereo.
Nature is amazing 🤩.