1. Noise Pollution Chapter 16 1

2. What’s the difference between a sound and a noise? (Intro & Section 16.3) 2

3. Pressure Waves (Section 16.1) Source 3

4. Sound Pressure Level SPL = 10 log (P 2 /P o 2 ) P o = 0.00002 Pa Units: dB 4

5. Typical SPLs SourceSPL (dBA) Insect wings humming27 Rain patter on tent30 Frog chorus (distant)30 Locomotive (17 mi)30 Elk eating31 Jet overflight44 Tourist car idling48 Morning birdsongs50 City traffic74 Indianapolis Motor Speedway124 Measurements by Gordon Hempton, “an acoustic ecologist and sound recordist” 5

6. Changes in Sound Energy Decibel Addition For n sources of the same dB: SPL Total = 10 log n + SPL o 6

7. In-Class Activity Your company is purchasing an additional piece of manufacturing equipment. You have two choices. One brand generates 91 dB(A); another brand costs 10% more but generates 88 dB(A). You determine that the current level of noise in the production area is 88 dB(A). The workers are on 8-hour shifts. The OSHA 8-hour noise limit for the area is 93 dB(A). The company has been doing well and has thoughts of expanding production at this location in the near future. Determine which piece of equipment to purchase. 7

8. Perception of Changes 8

9. Effect of Distance Point SourceLine Source 9

10. Effect of Distance  Point source:  SPL = 20 log (D/D o ) 6 dB/DD  Line source:  SPL = 10 log (D/D o ) 3 dB/DD  Hard site:  SPL = 10 log (D/D o ) 3 dB/DD  Soft site:  SPL = 15 log (D/D o ) 4.5 dB/DD 10

11. Calculating SPL SPL average from a frequency analysis N = number of measurements taken 11

12. In-Class Activity Octave Band (Hz)SPL (dB) 31.530 6340 12510 25030 500128 100080 200010 40002 80000 12

13. Other Issues (Section 16.2) Time L eq SPL Time Varying SPL 13

14. Weightings 14

15. Noise Abatement and Control (Sections 16.4 and 16.5) Who regulates noise levels? 15

16. Noise Abatement and Control What are some options for abating or controlling traffic noise? 16

17. Some Info about Noise Barriers  How effective are they?  When are they considered?  When are they installed?  Of what are they constructed? 17

18. Metal 1984 1985 18

19. Light Pollution 19

20. Earth at Night 20

21. Mexico City 21

22. Orion: Rural vs. Urban Sky 22

23. Solutions? 23