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HS 471 NOISE POLLUTION Chapter 13

HS 471 NOISE POLLUTION Chapter 13. NOISE. Noise = unwanted sound Characteristics: Frequency (pitch), Hz Amplitude (intensity, loudness), dB Human hearing ability: 20 - 20,000 Hz Maximum sensitivity: 1,000 – 5,000 Hz A- weighting Human speech: 500 – 2,000 Hz. Noise Definitions.

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HS 471 NOISE POLLUTION Chapter 13

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  1. HS 471NOISE POLLUTIONChapter 13

  2. NOISE Noise = unwanted sound Characteristics: Frequency (pitch), Hz Amplitude (intensity, loudness), dB Human hearing ability: 20 - 20,000 Hz Maximum sensitivity: 1,000 – 5,000 Hz A- weighting Human speech: 500 – 2,000 Hz

  3. NoiseDefinitions Frequency • Number of times per second a vibrating body traces one complete cycle of motion • Cycles/second= Hertz (Hz) = f

  4. SOUND LEVELS

  5. Source Intensity Level # of Times Greater Than TOH Threshold of Hearing (TOH) 0 dB 100 Rustling Leaves 10 dB 101 Whisper 20 dB 102 Normal Conversation 60 dB 106 Busy Street Traffic 70 dB 107 Vacuum Cleaner 80 dB 108 Large Orchestra 98 dB 109.8 140 dB 1014 Military Jet Takeoff Walkman at Maximum Level 100 dB 1010 Front Rows of Rock Concert 110 dB 1011 Threshold of Pain 130 dB 1013 Instant Perforation of Eardrum 160 dB 1016

  6. NOISE INDUCED HEARING LOSS Hearing Loss: 1. Temporary Threshold Shift (TTS) 2. Permanent Threshold Shift (PTS) 3. Presbycusis Mechanisms of Hearing Loss: 1. Sensorineural 2. Conductive

  7. NOISE INDUCED HEARING LOSS

  8. NOISE INDUCED HEARING LOSS

  9. NOISE INDUCED HEARING LOSS Effects of Hearing Loss: 1. Loss in hearing high-frequency sounds 2. Tinnitus 3. Stress 4. Teratogenic effects? 5. Learning ability 6. Safety – occupational settings in particular 7. Sleep disruption

  10. Rule Of Thumb • If you have to raise your voice to be heard by someone less than three feet away, than you need hearing protection

  11. NOISE CONTROL Community Noise : • 50 dB daytime • 55 dB for 30 minutes • 60 dB for 5 minutes • 65 dB for 1 minute • cannot be greater than 70 dB • Night time variations Occupational settings: 85 dB action level 90 dB TWA Control methods???

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