Highest frequency of frog croak

The highest frequency of croak emitted by any species of frog is 128 kHz, voiced by the concave-eared torrent frog (Odorrana tormota) of eastern China. Indeed, this croak is actually ultrasonic, well beyond the range of human hearing (which cannot detect sound frequencies above 20 kHz). The reason that this frog produces such a high-frequency croak is to overcome the very loud low-frequency sound of the waterfalls nears which it lives in order to communicate with others of its species.