ABSTRACT
Two important characteristics of hearing emerge: the frequency range and the maximum sensitivity. This chapter aim to use these characteristics for comparisons. Profound increases in absolute sensitivity to higher frequencies and in the frequency range of hearing and considerable inter- and intraorder variance in hearing function characterizes the mammals. Because of the variation in hearing function within the mammals it is difficult to point to one taxon as representative of the class. In the mammals increases in sensitivity and in frequency range have added considerable versatility to the hearing function. Some mammals, however, such as man, cat, and desert rat, possess exceptionally good low-frequency sensitivity not seen in other vertebrate taxa. Reliable behavioral measures of hearing for the lower vertebrates are sparse. The chapter outlines some of the more obvious changes in hearing function that may have occurred in the evolving vertebrates.
