Sound

”Ceaseless Sound” – Little Ding-Dong Adventure of Sound

Have you ever played “telephone”? Connect two paper cups with a threat to make small telephones that can be used to pass little secrets to a friend on the other end. This line is the medium that transfers sound. The bell telephone uses the air in tubes to transfer sound. As the sound is restricted within a tube, the sound waves reflect along the walls of the tube until they reach the other end.

Use your brain and think about how astronauts in space communicate with each other.

UFO House  If you project an audio source on the point F′in the oval, the walls of the oval will reflect all sound to point F. When this principle is used in architecture, if two people stand at the two points in an oval structure, you can still clearly hear each other even if it’s very noisy indoor.

When you want to talk to people at a further distance, you cup your hands around your mouth to talk. What your hands are doing is acting as a speaker. It can reflect sound and focus them in a specific direction; this prevents sound from dispersing and lets it travel further.

The instrument used to measure the strength of sounds is a decibel meter. It uses (decibels) as a unit of measurement and the higher the decibel, the louder the sound; sounds over 100 decibel are considered noise. Decibels are the unit to measure the strength of sound, and sounds over 130 decibels are ultrasound.

Think About It

1. Kids, if we observe the sounds around us, how many decibels are they?
2. Kids, how do you identify noise? What effects do noise have on people?

◎ ROAR……do you know the secret of decibels?

0decibels→

Sound that is barely heard: a light breeze rustling leaves

20decibels→

Low murmuring: the sounds of a quiet office

40decibels→

Clock ticking: normal office conversations

80decibels→

Sounds heard from within the car; the sounds of a busy street

100decibels→

Train noises; a sharp whistle under a steel bridge.

120decibels→

Airplane engine; sounds that hurt the ears.