SOUND - ULTRASONIC - ECHO

WHAT HAPPENS WHEN AN AIRCRAFT BREAKS THE SOUND BARRIER???

Jets that fly faster than sound compress the air at the front. This forms a head wave. After a certain point of time, the pressure of the air gets discharged like an explosion. As a result, a loud bang takes place and we hear a loud sound. However, ultrasonic sounds are not audible to us. Bats and other propagates in the form of waves. Because of this reason we notice a change in the pitch of the siren of the vehicle passing us.

HOW DO WE PERCEIVE SOUND???

Sound is produced when the chords of a guitar are set in vibration. This vibratory movement then propagates in the form of waves, like the waves that arise when a stone falls in water. Waves can travel only in a medium such as water or air, but the vacuum is completely silent. Sound waves compress the air. Sometimes sound compresses the air so strongly that it causes pain in the eardrum because of the high pressure of the waves. Very deep sounds propagate into the ground, and our body feels vibrations. This is why, the deaf can also perceive sound and dance to it..!

WHAT IS AN ECHO???

If you call out your name in the direction of a vertical, bare rocky wall, you will hear it again after some time. An echo comes because the sound waves are reflected back from the wall. When sound is produced in enclosed spaces, such as churches and gymnasiums, multiple reflections build up and blend together. This phenomenon is known as reverberation.

DID YOU KNOW THAT????

•HARD MATERIALS CONDUCT SOUND BETTER THAN SOFT MATERIALS. FOR THIS REASON SOFT MATERIALS ARE GOOD SOUND ABSORBERS.
•SOLDIERS SOMETIMES DIE OF THE BANG AFTER A GRENADE EXPLODES NEAR THEM. THEIR AIR SACS CAN BURST BY THE PROPAGATION OF EXPLOSIVE SOUND.

•ASTRONAUTS CAN TALK IN SPACE EVEN WITHOUT RADIO. THEY ONLY NEED TO PRESS THEIR HELMETS TOGETHER.