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# Selection of ear defenders

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### Selection of ear defenders

1. 1. Mike Slater
2. 2. First, consider technical performance
3. 3. To do this, you’ll need information from the supplier of the proposed ear defenders
4. 4. Supplier’s Information Peltor Optime 1 Octave (Hz) 125 250 500 1000 2000 4000 8000 Mean attenuation (dB) 11.6 18.7 27.5 32.9 33.6 36.1 35.8 Standard deviation (dB) 4.3 3.6 2.5 2.7 3.4 3.0 3.8 Assumed protection (dB) 7.3 15.1 25.0 30.2 30.2 33.1 32.0 H = 32 M = 25 L = 15 SNR = 27
5. 5. Supplier’s Information Peltor Optime 1 Octave (Hz) 125 250 500 1000 2000 4000 8000 Mean attenuation (dB) 11.6 18.7 27.5 32.9 33.6 36.1 35.8 Standard deviation (dB) 4.3 3.6 2.5 2.7 3.4 3.0 3.8 Assumed protection (dB) 7.3 15.1 25.0 30.2 30.2 33.1 32.0 H = 32 M = 25 L = 15 SNR = 27 Assumed protection = mean attenuation – 1 standard deviation
6. 6. Supplier’s Information Peltor Optime 1 Octave (Hz) 125 250 500 1000 2000 4000 8000 Mean attenuation (dB) 11.6 18.7 27.5 32.9 33.6 36.1 35.8 Standard deviation (dB) 4.3 3.6 2.5 2.7 3.4 3.0 3.8 Assumed protection (dB) 7.3 15.1 25.0 30.2 30.2 33.1 32.0 H = 32 M = 25 L = 15 SNR = 27 Data for simplified methods
7. 7. There are 3 methods:  Using octave band data  H M L method  SNR method
8. 8. There are 3 methods:  Using octave band data  H M L method  SNR method Most accurate method
9. 9. There are 3 methods:  Using octave band data  H M L method  SNR method Simplified methods
10. 10. Octave Band Method
11. 11. Octave band method 1. Undertake octave band analysis of noise
12. 12. Octave band method 1. Undertake octave band analysis of noise 2. Obtain mean attenuation and standard deviation for ear defenders
13. 13. Octave band method 1. Undertake octave band analysis of noise 2. Obtain mean attenuation and standard deviation for ear defenders 3. Calculate assumed protection in each octave band (mean – 1 standard deviation)
14. 14. Octave band method 1. Undertake octave band analysis of noise 2. Obtain mean attenuation and standard deviation for ear defenders 3. Calculate assumed protection in each octave band (mean – 1 standard deviation) 4. Subtract assumed protection from noise levels in each octave band
15. 15. Octave band method 1. Undertake octave band analysis of noise 2. Obtain mean attenuation and standard deviation for ear defenders 3. Calculate assumed protection in each octave band (mean – 1 standard deviation) 4. Subtract assumed protection from noise levels in each octave band 5. Correct for A weighting
16. 16. Octave band method 1. Undertake octave band analysis of noise 2. Obtain mean attenuation and standard deviation for ear defenders 3. Calculate assumed protection in each octave band (mean – 1 standard deviation) 4. Subtract assumed protection from noise levels in each octave band 5. Correct for A weighting 6. Calculate assumed overall level at ear
17. 17. Octave band method 1. Undertake octave band analysis of noise 2. Obtain mean attenuation and standard deviation for ear defenders 3. Calculate assumed protection in each octave band (mean – 1 standard deviation) 4. Subtract assumed protection from noise levels in each octave band 5. Correct for A weighting 6. Calculate assumed overall level at ear 7. HSE recommend a 4 dB(A) correction is applied to take account of "real world" factors
18. 18. Octave band centre frequency (Hz) Measured level (dB) Measured levels 125 83.5 250 85.4 500 83.9 86.2 dB(A) 1K 2K 81.7 4K 78 8K 73.6 92.8 dB(C) Here’s some data from a noise survey 49
19. 19. Octave band centre frequency (Hz) 125 250 500 1K 2K 4K 8K Measured level (dB) 83.5 85.4 83.9 81.7 78 73.6 49 Assumed protection provided by ear defenders (dB) 7.3 15.1 25.0 30.2 30.2 33.1 32.0 Level at ear wearing ear defenders (dB) A weighting correction Level at ear wearing ear defenders (dBA)
20. 20. Octave band centre frequency (Hz) 125 250 500 1K 2K 4K 8K Measured level (dB) 83.5 85.4 83.9 81.7 78 73.6 49 Assumed protection provided by ear defenders (dB) 7.3 15.1 25.0 30.2 30.2 33.1 32.0 Level at ear wearing ear defenders (dB) A weighting correction Level at ear wearing ear defenders (dBA) Assumed protection is mean attenuation – 1 standard deviation
21. 21. Octave band centre frequency (Hz) 125 250 500 1K 2K 4K 8K Measured level (dB) 83.5 85.4 83.9 81.7 78 73.6 49 Assumed protection provided by ear defenders (dB) 7.3 15.1 25.0 30.2 30.2 33.1 32.0 Level at ear wearing ear defenders (dB) 76.2 70.3 58.9 51.5 48.2 40.5 A weighting correction Level at ear wearing ear defenders (dBA) Level at ear = measured level – assumed protection 17.0
22. 22. Octave band centre frequency (Hz) 125 250 500 1K 2K 4K 8K Measured level (dB) 83.5 85.4 83.9 81.7 78 73.6 49 Assumed protection provided by ear defenders (dB) 7.3 15.1 25.0 30.2 30.2 33.1 32.0 Level at ear wearing ear defenders (dB) 76.2 70.3 58.9 51.5 48.2 40.5 17.0 A weighting correction -16.1 -8.6 -3.2 0 1.2 1 -1.1 Level at ear wearing ear defenders (dBA) These are the specified correction factors for the A weighting
23. 23. Octave band centre frequency (Hz) 125 250 500 1K 2K 4K 8K Measured level (dB) 83.5 85.4 83.9 81.7 78 73.6 49 Assumed protection provided by ear defenders (dB) 7.3 15.1 25.0 30.2 30.2 33.1 32.0 Level at ear wearing ear defenders (dB) 76.2 70.3 58.9 51.5 48.2 40.5 17.0 A weighting correction -16.1 -8.6 -3.2 0 1.2 1 -1.1 Level at ear wearing ear defenders (dBA) 60.1 61.7 55.7 51.5 49.4 39.5 15.9 These values represent the A weighted levels at the ear when the ear defenders are worn
24. 24. Octave band centre frequency (Hz) 125 250 500 1K 2K 4K 8K Measured level (dB) 83.5 85.4 83.9 81.7 78 73.6 49 Assumed protection provided by ear defenders (dB) 7.3 15.1 25.0 30.2 30.2 33.1 32.0 Level at ear wearing ear defenders (dB) 76.2 70.3 58.9 51.5 48.2 40.5 17.0 A weighting correction -16.1 -8.6 -3.2 0 1.2 1 -1.1 Level at ear wearing ear defenders (dBA) 60.1 61.7 55.7 51.5 49.4 39.5 15.9 Level at ear wearing ear defenders = 64.9dB(A) Attenuation = 86 – 65= 21 dB(A)
25. 25.  Calculated level at ear wearing ear defenders = 65 dB(A)  Adjust by 4 db(A) to take account of “real world factors”  So level at ear is 69 dB(A)
26. 26. Simplified Methods  HML  high, medium and low  SNR  “single number rating”
27. 27. H M L Method
28. 28. HML Method 1. Measure level in dB(A) = (LA) 2. Measure level in dB(C) = (LC) 3. If Lc - LA is >2:  M  L   PNR  M   L C  L A  2  8   4. Otherwise:  H  M   PNR  M   L C  L A  2  4  
29. 29. HML Method  The PNR is subtracted from the A weighted sound pressure level to give the level experienced by the wearer in dB(A)
30. 30. Example Measured levels  86.2 dB(A)  92.8 dB(C)
31. 31. Example Measured levels  86.2 dB(A)  92.8 dB(C) Difference is 6.6 dB > 2, so use L and M values
32. 32. Supplier’s Information Peltor Optime 1 Octave (Hz) 125 250 500 1000 2000 4000 8000 Mean attenuation (dB) 11.6 18.7 27.5 32.9 33.6 36.1 35.8 Standard deviation (dB) 4.3 3.6 2.5 2.7 3.4 3.0 3.8 Assumed protection (dB) 7.3 15.1 25.0 30.2 30.2 33.1 32.0 H = 32 M = 25 L = 15 SNR = 27
33. 33.  M  L   PNR  M   LC  LA  2  8   LC = 92.8 dB LA = 86.2dB M = 25 L = 15
34. 34.  25  15   PNR  25   92.6  86.2  2  8   So PNR = 19.5
35. 35. PNR = 19.5 level experienced by the wearer = LA – PNR = 86.2 – 19.5 = 66.7 = 67 dB(A)
36. 36.  Calculated level at ear wearing ear defenders = 67 dB(A)  Adjust by 4 db(A) to take account of “real world factors”  So level at ear is 71 dB(A)
37. 37. SNR (Single Number Rating) Method
38. 38. SNR Method  The effective A weighted sound pressure level at the ear is given by subtracting the SNR value from LC
39. 39. Supplier’s Information Peltor Optime 1 Octave (Hz) 125 250 500 1000 2000 4000 8000 Mean attenuation (dB) 11.6 18.7 27.5 32.9 33.6 36.1 35.8 Standard deviation (dB) 4.3 3.6 2.5 2.7 3.4 3.0 3.8 Assumed protection (dB) 7.3 15.1 25.0 30.2 30.2 33.1 32.0 H = 32 M = 25 L = 15 SNR = 27
40. 40. SNR Method Level at ear = LC – SNR = 92.6 – 27 = 65.6 = 66 dB(A)
41. 41. SNR Method  Calculated level at ear wearing ear defenders = 66 dB(A)  Adjust by 4 db(A) to take account of “real world factors”  So level at ear is 70 dB(A)
42. 42. Method Octave band HML SNR Level at ear in dB(A)* 69 71 70 * Adjusted for “real world” factors
43. 43. Don’t overprotect
44. 44. Don’t overprotect Aim for a level at the ear between 60 and 80 dB(A)
45. 45. HSE Guidance From HSE publication L108 “Controlling noise at work”
46. 46. We now need to consider other factors that will affect how well the ear defenders perform
47. 47. These include compatibility with the: • User • Job • Other PPE
48. 48. Here are some examples (there are many others)
49. 49. 1. Compatibility with the user
50. 50. Compatibility with the user Some people find wearing ear plugs uncomfortable
51. 51. Compatibility with the user Ear muffs can be uncomfortable to wear in hot conditions
52. 52. Compatibility with the user With ear muffs, glasses, jewellery and long hair can interfere with the seals that keep noise out
53. 53. 2. Compatibility with the job
54. 54. Compatibility with the job Wearing ear defenders can interfere with communication .... http://actrav.itcilo.org
55. 55. Compatibility with the job .... and make it difficult to hear alarms and audible signals
56. 56. 3. Compatibility with other PPE
57. 57. Compatibility with other PPE Wearing ear muffs with safety helmets presents particular problems
58. 58. Compatibility with other PPE Helmet mounted muffs can significantly reduce the attenuation provided by the muffs
59. 59. Compatibility with other PPE And, of course, safety glasses can interfere with the seal on ear muffs
60. 60. Once suitable ear defenders have been selected, there are other important considerations to ensure that they are effective when they’re being used.
61. 61. Once suitable ear defenders have been selected, there are other important considerations to ensure that they are effective when they’re being used. These include:
62. 62.  Fitting  Hearing protection zones  Enforcement  Care and maintenance  Training
63. 63. http://www.slideshare.net/mikeslater mike@diamondenv.co.uk http://diamondenv.wordpress.com Twitter: @diamondenv Mike Slater
64. 64. Mike Slater, Diamond Environmental Ltd. (mike@diamondenv.co.uk) This presentation is distributed under the Creative Commons Attribution-NonCommercial-ShareAlike UK:International Licence
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