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11.7 Noise pollution

11.7 Noise pollution. written as dB. Loudness of sound ( 音量 ). p.99. => The level of sound. - measuring unit: decibel ( 分貝 ). - The higher the decibel , the louder is the sound. - Can be measured with a decibel meter ( 分貝計 ).

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11.7 Noise pollution

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  1. 11.7 Noise pollution

  2. written as dB Loudness of sound(音量) p.99 => The level of sound. -measuring unit: decibel (分貝) - The higher the decibel, the louder is the sound. - Can be measuredwith a decibel meter (分貝計).

  3. - The following photos show two different kinds of decibel meters:

  4. soundlevel (dB) perception example – 100 – 80 – 60 – 30 quiet soft whisper (25 dB) – 10 – 0 Sound level and human’s perception very quiet sound breathing sound (10 dB) the lowest sound level that can be heard

  5. – 100 – 80 – 60 normal conversation (60 dB) acceptable – 30 quiet – 10 – 0 Sound level and human’s perception soundlevel (dB) perception example soft raining (50 dB) soft conversation in libraries (30 dB)

  6. – 100 annoying – 80 alarm clock (80 dB) noisy – 60 acceptable – 30 quiet – 10 – 0 Sound level and human’s perception soundlevel (dB) perception example busy traffic (70 dB)

  7. – 100 passing train (90 dB) annoying – 80 noisy – 60 acceptable – 30 quiet – 10 – 0 Sound level and human’s perception soundlevel (dB) perception example very noisy damage our ears crying baby (100 dB)

  8. road drilling (120 dB) disco (110 dB) – 100 annoying – 80 noisy – 60 acceptable – 30 quiet – 10 – 0 Sound level and human’s perception soundlevel (dB) perception example very noisy damage our ears

  9. jet plane taking off (130 dB) – 100 annoying – 80 noisy – 60 acceptable – 30 quiet – 10 – 0 Sound level and human’s perception soundlevel (dB) perception example rocket taking off (190 dB) very noisy damage our ears

  10. We can enjoy some sounds as music. However, sound can also be annoying noises.

  11. Noise (噪音) p.102 => annoying sound - Noise is a kind of pollution. It is a common problem in crowded cities.

  12. There are many people but less space in Hong Kong. We live in a densely-populated city. Noise pollution is serious.

  13. Do you know ? Can you give some examples of sources of noise in Hong Kong? repairing house construction site busy traffic playing mah-jong road drill playing hi-fi taking off and landing of plane burglar alarm

  14. - There are many loud sounds in our surroundings,including some of the objects we often use. Activity Corner J What are these objects? How do they affect us?Try to do to find out the answer. p.101

  15. Effects of noise pollution p.102 - causes mental stress - increases the heartbeat rate and blood pressure - disturbs our sleep - makes us difficult to concentrate, so accidents happen more easily - annoying, makes us become bad tempered more often

  16. e.g. in Chinese restaurants -Hearing sound level at 80 dBfor a long time, => may cause temporary or permanent damage to our ears. -Hearing sound level at 130 dB makes our ears feel pain, => because the eardrum vibrates too vigorously. -When sound level reaches 150 dB, => causes damage to the eardrum or ear bones, make us go deaf.

  17. Do you know ? According to an investigation done by a group of Australian scientists in 1998: Wear headphones to listen to music for more than 6 hours a week, the sense of hearing will decrease by 30 years.

  18. Do you know ? How can noise pollutionbecontrolled?

  19. e.g. disco, karaoke centre… Protecting our ears p.103 1 Avoid listening to loud musicfor a long time. 2Stay away from noisy places. 3Wear ear protectorswhen working at noisy places

  20. We should wear an ear protector when working at a noisy place - Prescribed bythe laws in HK: The employer cannot request employees to work in a place at sound level higher than 90 dBfor more than 8 hourswithout break.

  21. Noise control p.103 - HKSAR government has taken some measures to control noise: -It is an offence to make loud noisebetween 11 p.m. and 6 a.m.

  22. Pile drive Road drill Noisy construction works (including pile drive and road drill)are not allowedwithout a permit. public holidays between7 p.m.and 7 a.m.on weekdays

  23. - Schoolsin noisy environment are given special funding to install air-conditioners in their classrooms. - Residential areasclose to the highways are protected by noise barriers.

  24. While the government has spent a lot of money onnoise control, as responsible citizens, we have the responsibility to help reduce noise pollution.

  25. People with eye defects or ear defects are also part of the society. They need our support and love. How can we help them?

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