THE analysis of the frequency response to sound of individual nerve fibres in the orthopteran ear indicates that the fibres are most sensitive at a particular frequency (usually between 4 and 6 kHz), but that this frequency tends to be the same for all fibres1,2. The functional significance of this tuning may be associated with the fact that the maximum energy in the mating call lies in the 4.5–5.5 kHz range3. Little is known about the nature of the mechanism that contributes to the tuning curve itself. We have tried to discover if the tuning curve is simply mechanically determined or whether additional sensory/neural elements are involved.