A) Read the text.
________________________
An alarm clock rings, a dog *barks*, a voice calls, “Time to get up!” Every day is full of familiar
sounds, but what exactly is sound?
Sound is caused by a back and forth movement called *vibration*. Try this. Close your lips
and *hum*. While you are humming, feel your throat under your chin. Do you feel something
buzzing or vibrating? What you feel is caused by something moving back and forth very fast.
When you hum, the vocal cords in your throat vibrate back and forth. This makes the air
around them vibrate, which then creates the sound you hear.
Two things must happen to create a sound. First, something needs to vibrate and
create sound waves. Then, something like air or another *medium* needs to carry the sound
waves. You hear sounds more clearly if you are close to whatever is vibrating and making the
sound waves. The farther away that the sound waves *spread out*, the weaker they get. That
is why you can hear a friend standing right next to you better than if they are calling you from
across the street.
Sound travels not only through air, which is a gas, but through other mediums. In fact, sound
can travel through solids, liquids, and gases.
Think about sound traveling through solids, like a window or even a closed door. If you are
close enough, you can still hear sounds on the other side of a window or door.
How about liquids? Have you ever been underwater in a swimming pool when you have heard
someone’s voice or another sound? This is an example of sound traveling through a liquid—the
water in the pool.
One place that sound cannot travel is in outer space. Sound cannot travel through the emptiness,
or vacuum, of space. There is no sound in outer space because there is no medium to carry it.
B) Read the text again and answer the questions accordingly.
1. What is sound caused by?
.
2. What are the two things that are needed for sound to travel?
.
3. What is the reason you hear sounds more clearly when you are close to where it comes
from?
.
4. Is there sound in outer space? Why/Why not?
.
5. What title would you write for this text?
.
C) Find words or phrases in the text which mean the same as:
1. to cover, or to make something cover, a larger and larger area

2. the short loud sound made by dogs and some other animals

3. to sing a tune with your lips closed

4. a substance that something exists or grows in or that it travels through

5. a continuous shaking movement or feeling

II - VOCABULARY
D) Complete the sentences by selecting words from Exercise C.
1. He began to ____________ along with the music.
2. There's more room to _____________ in first class.
3. Air is a ____________ that carries the sound waves.
4. The dog started to ____________ furiously at a cat while we were chatting.
5. We could feel the __________________ from the trucks passing outside.