Behavioral tests of hearing and sound localization in the North American pocket gopher (Geomys bursarius) show that it is unique among mammals. It has a severely attenuated range of hearing and only rudimentary ability to localize sound. In these respects, the hearing of gophers can be properly termed 'vestigial' and suggests that life underground can produce as severe a change in hearing as a light-less world produces in vision or an odorless world produces in olfaction.