Question

# Ultrasound has a frequency of vibrationA. Between $20$ and $20000Hz$B. Below $20Hz$C. Above $20000Hz$D. Between $500$ and $10000Hz$

Human ears can receive up to a particular range of sounds. The range of frequency lying between $20Hz$ and $20000Hz$ is perceivable to humans. Sounds that have a frequency greater than $20000Hz$ are called ultrasonic sounds. Some animals can hear ultrasonic sounds. Dogs can hear sounds greater $20000Hz$ than but humans cannot hear such sounds. The frequency range that dogs can hear varies from $67 - 45000Hz$. The frequency that lies between $20000Hz$ and $45000Hz$ can be heard by dogs but not by humans.
The sounds that have a frequency less than $20Hz$ are called infrasound. This range of sounds is additionally inaudible to humans. The capacity of perception varies in several animal species. For different purposes like predation, detection of danger, communication, navigation, etc. Many animals use sounds. Some animals have special organs to produce sounds. Animals like whales, animals, etc. can detect infrasound and use it for communication. Unwanted sound is called noise.