How cicadas interpret acoustic signals

The vertebrate ear can analyze the frequency components of sound with high resolution, recognizing complex acoustic signals even against a noisy background. By contrast, insect ears can separate only broad-frequency bands, resulting in a categorical perception of sound. We have discovered an insect, the cicada Tettigetta josei, that has a capacity for fine-frequency resolution, which could explain the evolution of frequency-modulated communication signals in cicadas.