Hearing capabilities are essential for many animals, including birds and mammals, who heavily rely on acoustic communication. Despite some differences in their hearing systems, birds and mammals share common features in their auditory responses. Among these groups, some species, e.g. barn owl (Tyto alba), cat (Felis catus), are well recognized by their heightened sensitivities at particular frequency ranges. However, the molecular bases of their hearing sensitivities are largely unknown. The purpose of this study is to find candidate genes responsible for the high hearing sensitivities in the genomes of cat and the barn owl, via comparison with other non “high-sensitive”. Birds and mammals’ species were selected, for which the whole genomes and auditory sensitivities are described. For a genome-wide candidate analysis, we have developed a pipeline to detect positively selected genes, using PAML with the branch-site model. The functionality of the genes detected in the analysis and their relation to the hearing system on the highly sensitive species are discussed.