Page 135 - Primary Six Notes

Echoes

 An echo is a reflected sound formed as a result of obstruc-

tion of sound waves.

 A Echoes have the same characteristic as the original sound.

 A Smooth hard surfaces produce the best echoes while soft

surfaces absorb sound.

Advantages of echoes:

 Bats use high pitched echoes to trap their prey at night in

darkness.

 Bats use echoes to dodge obstacles at night.

 Pilots use echoes from hills, cliffs ends of tall building to

avoid accidents.

 Sailors and sea men use echoes to determine the depth of

the sea using an echo sounder.

Disadvantages of echoes.

 Echoes make sound difficult to interpret.

 Echoes cause accidents and noise pollution.

How are echoes reduced in cinema halls and theatres.

 Use of thick curtains.

 Use of porous materials such as soft boards in the speakers.