Question: How do some animals hear infrared sounds?@chloe

Chloe Kinsella answered on 14 Nov 2014:

By infrared sounds do you mean high pitched sounds?
Lets take dogs as an example. Dogs can hear in frequencies ranging from around 40 Hz to 60 kHz, depending on the breed and age. Humans can only hear much lower, from 12 Hz to 20 kHz, and the older you get, the less of this you hear. Dogs have more than 18 muscles that enable them to move their ears so they can more precisely locate a sound. They have a longer ear canal than we do, which serves as an effective funnel to the eardrum. The cochlea, in the inner ear, makes 3 1/4 turns compared to a humans 2 1/2 turns, also making dogs hearing sharp.In addition, dogs can hear sound up to four times farther than us humans. So the next time you hear your dog barking at the wind, he/she can probably hear something very interesting that you are unable to.

Bats have the most acute hearing of any non-aquatic animal, due to their ultrasonic echolocation (Echolocation works very similar to a sonar system in a submarine). Most species of bats use frequencies in the 20-80 kHz range, although some can hear frequencies as high as 120-250 kHz. Dolphins can use even higher frequencies of up to 280 kHz!