ANALYSIS OF SOUND BY THE SPRAT EAR

In the acoustico-lateralis systems of vertebrates the individual hair cells are usually polarised in their responses to displacements of the liquid in which they lie, and are often arranged in back-to-back pairs or groups with different polarities. A simple example to investigate, mechanically as well as electrically, is the utriculus of the sprat (Clupea sprattus L.). The acoustico-lateralis system of the sprat and other clupeids has two partly gas-filled bony bullae which transform pressure changes into liquid displacements capable of stimulating the sense organs of the ear and lateral line1-3. With its related structures the utriculus is a very sensitive sound pressure detector which has one population of receptors that respond to the compressions and another that respond to the decompressions of a sound wave. We now give additional evidence that this type of organisation is unlike that of the mammalian cochlea in being specialised more for the detection of phase/time relationships than for frequency analysis. © 1979 Nature Publishing Group.