Pressure difference receiving ears.

Directional sound receivers are useful for locating sound sources, and they can also partly compensate for the signal degradations caused by noise and reverberations. Ears may become inherently directional if sound can reach both surfaces of the eardrum. Attempts to understand the physics of such pressure difference receiving ears have been hampered by lack of suitable experimental methods.

The role of pressure difference reception in the directional hearing of budgerigars (Melopsittacus undulatus).

In many birds, the middle ears are connected through an air-filled interaural pathway. Sound transmission through this pathway may improve directional hearing. However, attempts to demonstrate such a mechanism have produced conflicting results.

Karl von Frisch lecture. Signals and flexibility in the dance communication of honeybees.

Progress in understanding dance communication in honeybees is reviewed. The behaviour of both dancers and follower bees contain flexible and stereotypic elements. The transfer of specific information about direction and distance probably involves more than one sensory modality.

The Tuned Cricket.

Communication by means of sound is not always easy. Sound suffers much attenuation and degradation close to ground. Crickets have adapted to this by exploiting sharply tuned mechanical systems.