Q28 of 29 Page 180

You might have observed that sometimes your pet dog starts barking though no one is seen near in its surroundings or no disturbance heard nearby. Does this observation raise any doubts in your mind about the peculiar behavior of dog after your understanding about ‘range of hearing the sound’. If yes, write them.

Dogs can hear the sound ranging from 67 Hz to 45000 Hz. Therefore it can also hear the ultrasonic sound waves. When there is other creature or anything that produces ultrasound waves the dog detects it and starts barking to warn us. We humans can hear sound waves from 20 Hz to 20000 Hz hence we can’t hear the sound waves that can be heard by dog.


More from this chapter

All 29 →
25

A man is lying on the floor of a large, empty hemispherical hall, in such a way that his head is at the centre of the hall. He shouts “Hello!” and hears the echo of his voice after 0.2 s. What is the radius of the hall? (Speed of sound in air = 340 m/s)

 26

“We know that sound is a form of energy. So, the large amount of energy produced due the sound pollution in cosmopolitan cities can be used to our day to day needs of energy. It also helps us to protect bio diversity in urban areas”. Do you agree with this statement? Explain.

 27

How do you appreciate efforts of a musician to produce melodious sound using a musical instrument by simultaneously controlling frequency and amplitude of the sounds produced by it.

 1

Find out the information about names of animals and their photographs from internet, which communicate using infra-sonic or ultra-sonic sound and prepare a scrap book.