Sounds are distinct puffs of air. Humans are sensitive to a continuum of sound waves from 20 to 20,000 Hz. The upper limit diminushes with age. The ultrasonic hearing of dogs is well known. Predatory owls and wolves can hear much quieter sounds than humans. The same is true of many insects, usually sensing physical vibrations through legs and antennae.

Bats echo-locate in the ultrasonic range. According to Gould and Gould (1994):

Some species can hear sounds as high as 100,000 Hz, which they project from the mouth or nose. From the time delay, strength, and modulation of the echoes of these sounds, bats can judge the location of obstacles and the position, direction of movement and often the species of flying prey.

Gould, James L. and Gould, Carol Grant (1994) The Animal Mind. Scientific American Library, New York.