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1. Loud but clear

 Picture 1. Colin can make a wave travel down the rope.

 Sound waves What is a wave? You can make a simple wave on a piece of rope or elastic. Imagine the rope stretched between two people – Colin and Joanne. If Colin shakes the end of the rope, then the shake travels down the rope. If he does three shakes, then all three of them travel along the rope. So he can send a message or energy to Joanne by shaking the rope. He did this using a wave (picture 1). Types of wave
 Picture 2. A wave on a slinky is similar to a sound wave being carried by air particles.
 Sound is also a wave. It is carried by the particles of the air. If Colin started talking to Joanne, his vocal chords would move backwards and forwards – or vibrate. The vibrations of his vocal chords would make the air particles near his mouth move. The movement would be carried as a wave through the air from Colin’s mouth to Joanne's ear. It's a bit like a wave on a slinky (picture2).

 Picture 3. The outer ear collects the sound, which is amplified in the middle ear and turned to electrical signals in the inner ear.
 How do we hear? When a sound wave reaches Joanne's ear, the moving air particles make her ear drum vibrate. These vibrations are amplified about twenty times by the bones in the middle ear, which act as levers. Finally, the vibrations reach the inner ear where they are turned into electrical signals by the cochlea.

 Question 1-1.

Fill in the gaps in the paragraph below. Choose the best answer in each case.

A makes a sound. Sound is an example of a . It is carried through the air by . It is similar to a wave on .
 Summary                   Close Sound is a waveIt needs a medium to travel (it won't get through a vacuum) Sound is like a wave on a slinky