Why do I live on the 30th floor? There will be chirping sounds outside the window, like birds chirping, but birds are chirping. Baidu said the mouse climbed up.

Hello, the chirp outside the window in the evening is the cry of bats. Most species of bats have severely deteriorated their eyesight. In flight, bats emit intermittent sound waves in order to identify the direction and catch flying insects in the air, and rely on sound wave reflection to avoid obstacles and prey. Most of the sound waves emitted by bats are ultrasonic waves, the frequency of which exceeds the hearing range of human ears, but some high-frequency sound waves are quietly heard by human ears, that is, chirped sound waves will swing from side to side with the flight trajectory of this bat.