Acoustical response of hair receptors in insects

Abstract

A detailed mechanical model is developed to account for the behaviour of hair-like acoustical sensory receptors in insects. For the small hair diameters commonly found, it is concluded that the force acting on the moving hair is caused almost entirely by the viscosity of the air, as analyzed long ago by Stokes. The result of this viscous force is to provide a bending moment about the base of the hair that is proportional to the acoustic particle velocity but that lags behind it by about 135°. In addition the viscous force increases the moment of inertia of the hair by a large and frequency dependent addition, and provides a viscous damping term of sufficient magnitude to reduce the Q value to near unity.

The measurements of Tautz (1977) on the thoracic hairs of the caterpillarBarathra brassicae are discussed in detail in terms of the model. Many of these observations are well accounted for, though a few discrepancies remain. Show more