8Le - Noise Levels SLB
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Noise Levels 8Le
description
Powerpoint on Noise levels 8L KS3
Transcript of 8Le - Noise Levels SLB
Noise Levels
8Le
Learning Objectives
• Recall that unpleasant sounds are called noise.• Recall that a decibel is a unit for the loudness of
sound.• Explain that soundproofing can be used to
reduce noise.• Recall how sounds are measured.• Explain the meaning of threshold of hearing.• Explain how soundproofing works
Annoyed by noise
• Sometimes sounds around you can be very annoying.
• Sound can damage your ears if its too loud or goes on for too long.
• Unpleasant sound is often called noise.
• We can measure how loud sound using a sound intensity meter in decibels (dB)
Guess the sound!!
• What is the sound?
• What decibel could it be?
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VERYLOUD
QUIET
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Guess the sound!!150
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VERYLOUD
QUIET
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1. Airplane2. Bird singing3. Drums4. Motorbike5. Bell6. Clock ticking7. Shouting8. Whispering/yawn9. City noise/traffic
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10 dB
20 dB
40 dB
50 dB
90 dB
100 dB
110 dB
120 dB
140 dB
Threshold of hearing• This is the quietest sound we can hear. • 0dB.
• The loudness of a road drill is 90dB.• This is the top limit accepted by law. • A noisy factory can be louder than this!• Dance speakers in a nightclub = 90dB.
• Sound becomes painful at 80dB!• Ear drums break at 180dB!!
FACT
• In November 1999, France brought out a law which limited the noise levels of personal stereos.
• Since 2000 no personal stereos can be played louder than 100dB.
Questions
1. What is the instrument which measures sound?
2. What units do we measure sound in?
3. What is the threshold of hearing?
4. What is the limit of acceptable noise?
5. Make a list of jobs which have a high level of noise.
Soundproofing• Houses near to an airport usually have
double glazed windows. Most of the air has been taken out from between the layers of glass.
• This makes it more difficult for sound to travel through – Why might this be?
• There are fewer particles to pass on vibrations.
Some people have to wear special ear protectors to stop their ears being damaged.
Noise can be reduced by soft things like curtains and carpets. The soft materials absorb some of the energy of
sound.
Practical – Soundproof designs
• Investigate which materials are the best for soundproofing.
• Choose the best way you think to collect and display the information.
• You will be given: bell, cardboard, paper, bubble wrap and other sound proofing materials.
Worksheet 8Le 2 or 3
Plenary – Zoo-reka!• The world renowned zoo and theme park ‘Zoo-
reka!’ has decided to employ people to help educate its visitors.
• You have been asked to lead tours and answer questions relating to the area of animals and sound.– How the enclosures keep the animals healthy and
clean.– How animals make sounds and what they use them
for.– How humans can listen to the sounds animals make.
•What would you say to Year 7’s about ‘Zoo-reka!’?
Level descriptors – ASP 336-337
Learning Objectives
• Recall that unpleasant sounds are called noise.• Recall that a decibel is a unit for the loudness of
sound.• Explain that soundproofing can be used to
reduce noise.• Recall how sounds are measured.• Explain the meaning of threshold of hearing.• Explain how soundproofing works
