Most animals, including the fishes and marine mammals, hear best through the frequencies they produce. Also, they have varying degrees of sensitivity to sounds of different frequencies.
According to scientists and audiologists, many animal species differ in their ability to hear at one frequency. Each species hearing abilities is often represented by a curve or an audiogram, which is a graph that shows the intensity versus the frequency. For example, all species of baleen whales, like the humpback and the blue whales, produce low frequency sounds. While all species of toothed whales, like the dolphins, produce high frequency sounds. Seals and sea lions, on the other hand, have increasing sensitivity to low and high frequencies of sound.
The animals considered to have the sharpest hearing ability are the owls. These birds have phenomenal hearing. Their ears, which have large ear holes situated at slightly different heights, allow them to pinpoint the vertical positions of sound sources. In terms of navigating using sound, pigeons are considered the best at it because they can hear sounds at exceptionally low frequencies. With hearing defense, the tiger moths are the best since they have evolved with super sensitive ears. They use these ears to hear if a bat is closing in on them, which helps them take evasive action.