Question

What is ultrasound?plz describe briefly why can't hear that soun?

Answer 1

We can sense something, because we have receptors for them. If we do not have receptors those things will go undetected. For example we cannot detect radio waves, X rays or gamma rays. Although radio waves are going across us we cannot sense them.

Even if we have receptors, they can not detect everything. We can detect only a part of it. How much we can detect depends on evolution. We have adapted ourselves to what we need. If in a spectrum, we are not used to certain part of the spectrum, then we slowly lose the ability to detect them or we never acquired them at all in the first place, as a part of evolution, simply because we dont need it.

We are not hearing ultrasound because, sound with frequency more than 20kHz has nothing much to do in our day to day life. Bats and some animals have them. They need it, because one of their other senses like vision are not that well developed, and they use this a a kind of replacement.

Answer 2

Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is no different from 'normal' sound in its physical properties, except in that humans cannot hear it.

 We can not hearing ultrasound because, sound with frequency more than 20kHz has nothing much to do in our day to day life. Bats and some animals have them. They need it, because one of their other senses like vision are not that well developed, and they use this a a kind of replacement.

hope it helps u..... ;)

@AV....