SOUND 8.2.1

SOUND 8.2

• Sound travels faster in hard, stiff materials such as steel. 

• The sound bounces off these materials. 

• This is

  called reverberation.

• Sound travels more slowly in soft, flexible materials such as rubber.

• The sound is drawn in, or absorbed,

  by these materials.

• This is called absorption.

Multiple Choice

Why is the school library covered with carpet?

• So everyone can make a lot of noise

• to help absorb sounds to keep it quiet

• because it looks good

• to help absorb sounds so it can stay noisy

Multiple Choice

Why is the school library covered with carpet?

• So everyone can make a lot of noise

• to help absorb sounds to keep it quiet

• because it looks good

• to help absorb sounds so it can stay noisy

Open Ended

Which picture shows sound being reverberated?

Open Ended

What is the sound bouncing off?

Open Ended

Which picture shows sound being absorbed?

Open Ended

What absorbs the sound? Can you write these objects?

• We use reverberation and absorption for measuring and for creating images.

• Ships use a sonar machine to measure the depth of the water.

• A computer on the ship measures how long it takes for the echo to return to the surface of the sea. 

• If it takes a long time, the water is deep.

  If it returns quickly, the water is shallow.

Open Ended

What does a sonar machine do?

Open Ended

What does it mean if the echo takes a long time

to get back to the ship?

• Doctors use sound to create

  images of babies when they

  are still inside their mothers.

  The sound is absorbed by the

  soft parts of the body and

  bounces off the hard parts,

  such as the bones. The doctors

  can see how the baby is

  developing and check

  for problems

• 
  

•