Many books from symposia describe the current status in well established fields of research, where much is known and where the loose ends are only details in the picture. The topic dealt with here does not fall into this pattern. The study of time as a parameter in its own right is difficult, and the loose ends tend to do­ minate the present picture. Although the book does provide the reader with an overview of the field, its main value is probably to act as a source of "food for thought" for those interested in the function of sense organs and nervous systems as substrates for behaviour. The Introduction is intended to provide the readers of the book with a short guide to the topiCS discussed in the different chapters. The rather detailed Index may help those looking for information on specific topiCS. The Index also explains most of the abbreviations used in the book. The basic idea of the Danavox symposia is to invite a small group of experts to discuss a rather narrow theme in sound communication. The small number of active par­ tiCipants has the advantage of encouraging intense dis­ cussions and of avoiding overloading the program. On the other hand, selecting the partiCipants is difficult.