Sound is measured in decibels (dB). We can hear sounds ranging from a low rumble up to a high pitched whistle.
The lowest sounds can sometimes be felt in the chest, while very shrill sounds may be so high that we cannot actually hear them. A bat’s squeak is at the limit of what human beings can hear, and many people cannot hear this noise at all.
Our hearing is not very sensitive compared to animals such as dogs, who can hear very high pitched sounds. Dogs are able to respond to a supersonic whistle that cannot be heard by human at all.