Structure of the Mammalian Cochlea

Two features distinguish mammalian hearing from auditory reception in fishes, amphibians, reptiles, and birds. First, the audible frequency range is significantly broader in mammals than in other vertebrate taxa due to the responsiveness of the mammalian ear to higher frequency sounds. Second, when compared with other vertebrates, mammals show considerably more species diversity in particular attributes of hearing such as the lower frequency limit of hearing, the upper frequency range of hearing, and the frequency of maximum sensitivity (Fay 1988). Some mammals, which might be termed hearing generalists, perceive a broad range of sound frequencies and show little variation in threshold sensitivity throughout a large portion of their hearing range. In contrast, other species, which could be called hearing specialists, respond to sounds within a more restricted bandwidth and generally display a greater sensitivity for particular frequencies, often those found within behaviorally relevant acoustic signals.