2. 10/1/99Created By: C. Miterko1 29 CFR 1910.95 برنامج الحفاظ على القوى السمعية

3. 10/1/992 What is Sound? ما هو الصوت Sound is what we hear and is produced by vibrating objects and reaches the listener’s ears as waves in the air or other media.Sound is what we hear and is produced by vibrating objects and reaches the listener’s ears as waves in the air or other media. When an object vibrates it causes slight changes in air pressure. These air pressure changes travel as waves through the air and produce sound.When an object vibrates it causes slight changes in air pressure. These air pressure changes travel as waves through the air and produce sound. الصوت ينتج من إهتزاز الأشياء ويكون على هيئة موجات تصل إلى الأذن. عندما تهتز الأشياء يحدث نتيجة لذلك تغيير بسيط فى ضغط الهواء. وهذا التغيير فى ضغط الهواء ينتقل فى الهواء على شكل موجات والتى بدورها تنتج الصوت

4. 10/1/993 عندما يتم خبط الطبلة بواسطة العصاة ، يهتز سطح الطبلة وعندما يتحرك سطح الطبلة للأمام يحدث تغيير موجب فى ضغط الهواء وعندما يتحرك سطح الطبلة للوراء يحث تغيير سلبى فى ضغط الهواء وهكذا يتحرك هذا الضغط على شكل موجات حتى يصل للأذن ونسمع الصوت.

5. 10/1/994 What is Noise? الضوضاء هى الأصوات غير المرغوب بها Hertz (Hz) يقاس بوحدة الهيرتز وهى عدد الذبذبات التى تنتج من تغيير ضغط الهواء فى الثانية الواحدة

6. 10/1/995 Frequency Humans can typically hear between 20 - 20,000 Hz تسمع الأذن البشرية الأصوات بين 20 – 20000 هيرتز التردد الخاص بالحديث العادى يكون فى حدود 3000 هيرتز الإنسان ذو الصحة الجيدة يمكنه أن يسمع الأصوات التى تحدث تغيير فى ضغط الهواء يبلغ 0.00002 Pa

7. 10/1/996 ونظرا لصغر وحدات التغيير فى ضغط الهواء فقد تم إستعمال وحدة أكبر تسمى الديسيبل dB وهى وحدة لوغاريتمية. ولتحويل وحدات الضوضاء من باسكال إلى ديسيبل يتم إستخدام المعادلة الأتية: ولتحويل وحدات الضوضاء من باسكال إلى ديسيبل يتم إستخدام المعادلة الأتية: dB = 20 log {sound pressure/Ref. Pressure (0.00002 Pa)} Sound pressure level in very quite room where the sound pressure is 0.002 Pa is: Lp (dB) = 20 log (0.002/0.00002) = 20 log 100 = 40 dB

8. 10/1/997 Common Sounds Common Sounds

9. 10/1/998

10. 9 How do we Hear? 1- الأذن الخارجية تلتقط موجات الصوت 2- تقوم الموجات بخبط طبلة الأذن فتسبب إهتزازها 3- تنتقل الإهتزازات من طبلة الأذن خلال المطرقة والسندان والركاب 4- بعد ذلك تنتقل هذه الذبذبات إلى الأذن الداخلية حيث توجد الكوكيلاة وبها ملايين الشعيرات الدقيقة التى تنقل هذه الذبذبات على شكل نبضات إلى المخ وبالتالى نسمع الصوت

11. 10/1/9910 Example In the field, we determined the loudness of two compressors right next to each other How loud is this area? –Do we add? –Do we add and take the average? 89 dB87 dB

12. 10/1/9911 Neither, because it is a log scale We use the following chart 82 dB + 83 dB = 86 dB 87 dB + 89 dB = 91 dB Difference in dB Values Add to Higher Level 0-1 dB3 dB 2-3 dB2 dB 4-9 dB1 dB 10 dB or more0 dB

13. 10/1/9912 How does the Safety Person determine noise levels Sound level meter –Determine the loudness (dB) of noise at any given moment moment يتم قياس الضوضاء بالمنطقة بواسطة جهاز قياس مستوى الضوضاء القياس يكون لحظى Personal Dosimeters –Worn by employees –Measures the average loudness in an 8 hour work shift “8hr. TWA” (Time Weighted Average) –يتم القياس بواسطة الدوزيميتر –القياس يكون خلال 8 ساعات متوسط

14. 10/1/9913

15. 10/1/9914

16. 10/1/9915 What does OSHA say? At 85 dB (8hr. TWA) (Action level) عندما تبلغ الضوضاء 85 ديسيبل (8 متوسط ساعات) يعتبر هذا هو الحد الواجب إتخاذ قرار فيه –Train employees –Make hearing protection available –Sample for noise levels –Do hearing tests –Notify employees of results

17. 10/1/9916

18. 10/1/9917 Hearing Conservation Program

19. 10/1/9918 Hearing Conservation Program Monitoring: Employers should monitor noise exposure levels to identify employees who are exposed to noise levels at or above 85 dBA averaged over 8 working hours, or an 8-hour time-weighted average (TWA). Noise level meters & Noise Dosemeter are used after being calibrated.

20. 10/1/9919 When the daily noise exposure has two or more noise exposures at different levels, their combined values should be considered. (Use the following formula) F(e) = (T(1) divided by L(1) + (T(2) divided by L(2)) + ……… (T(n) divided by L(n)) F(e)= The equivalent noise exposure factor T= The period of noise exposure at any essentially constant level. L= The duration of the permissible noise exposure at the constant level. If the value of F(e) exceeds unity (the value 1), the exposure exceeds PEL.

21. 10/1/9920 Example: 110 dbA 0.25 hours 100 dbA 0.5 hours 90dbA 1.5 Hours F(e) = (0.25/0.5) + (0.5/2)+(1.5/8) F(e)=0.5+0.25+0.1888 F(e) = 0.938 Since F(e) does not exceed unity (1), the exposure limit is within permissible limits Duration Per Day, Hours Sound Level dBA 8 90 692 495 397 2100 1½ 102 1 105 ¾ 107 ½ 110 ¼ 115

22. 10/1/9921 Audiometric Testing Should the noise level monitoring determine that employees are being subjected to levels equaling or exceeding a TWA of 85 dBA, the next step is to establish an audiometric testing program for those exposed at no cost to the employee.Should the noise level monitoring determine that employees are being subjected to levels equaling or exceeding a TWA of 85 dBA, the next step is to establish an audiometric testing program for those exposed at no cost to the employee. The important elements of an audiometric program include: Baseline audiograms, Annual audiograms, Control measures, Training, and follow-up procedures.The important elements of an audiometric program include: Baseline audiograms, Annual audiograms, Control measures, Training, and follow-up procedures.

23. 10/1/9922

24. 10/1/9923

25. 10/1/9924 Baseline Audiograms It is the reference audiogram against which future audiograms are compared.It is the reference audiogram against which future audiograms are compared. Must be provided within 6 months of an employee’s first exposure at or above 8-hour TWA of 85 dBA. (Control measures should be taken)Must be provided within 6 months of an employee’s first exposure at or above 8-hour TWA of 85 dBA. (Control measures should be taken) Baseline Audiogram must be preceded by 14 hours without exposure to workplace noise.Baseline Audiogram must be preceded by 14 hours without exposure to workplace noise.

26. 10/1/9925 Annual Audiograms After baseline audiogram has been taken, each employee exposed to noise levels at the 85 dBA or above shall have annual examination.After baseline audiogram has been taken, each employee exposed to noise levels at the 85 dBA or above shall have annual examination. Annual audiogram must be conducted within 1 year of the baseline.Annual audiogram must be conducted within 1 year of the baseline. Compared with baseline audiograms results.Compared with baseline audiograms results.

27. 10/1/9926 Continued To determine whether an employee has experienced any recordable hearing loss.To determine whether an employee has experienced any recordable hearing loss. The hearing loss is reffered to in the OSHA standard as :Standard Threshold Shift (STS).The hearing loss is reffered to in the OSHA standard as :Standard Threshold Shift (STS). OSHA defines STS as “a change in hearing threshold relative to the baseline audiogram of an average of 10 dB or more at 2000, 3000, and 4000, Hz in either ear.OSHA defines STS as “a change in hearing threshold relative to the baseline audiogram of an average of 10 dB or more at 2000, 3000, and 4000, Hz in either ear.

28. Example Baseline Audiogram 125 250 500 1K 2K 3K 4K 6K 8K 10 0 10 20 30 40 50 Baseline Audiogram (The initial audiogram taken by worker when first employed.)

29. Annual Audiogram (Showing STS) 125 250 500 1K 2K 3K 4K 6K 8K 10 0 10 20 30 40 50 BASELINE ANNUAL 16 9 8 16 + 9 + 8 = 33 33 / 3 = 11 Reportable Loss? NO STS ? YES

30. 10/1/9929 Control The standard states that if the 90 dB PEL is being exceeded, “feasible administrative or engineering controls shall be utilized.The standard states that if the 90 dB PEL is being exceeded, “feasible administrative or engineering controls shall be utilized. If fails, PPE shall be provided and used to reduce sound levels.If fails, PPE shall be provided and used to reduce sound levels.

31. 10/1/9930 Administrative Controls * Are defined as, “Methods of controlling employee exposures by job rotation, work assignment, or time periods away from the hazards.

32. 10/1/9931 Engineering Control Are defined as “ Methods of controlling employee exposures by modifying the source or reducing the quantity of contaminants released into the workroom environment.Are defined as “ Methods of controlling employee exposures by modifying the source or reducing the quantity of contaminants released into the workroom environment. Example: installing noise – absorbing acoustical foam or baffles to capture and deaden reverberating noise.Example: installing noise – absorbing acoustical foam or baffles to capture and deaden reverberating noise.

33. 10/1/9932

34. 10/1/9933 Hearing Protectors Hearing protectors shall be made available and shall be worn by all employees exposed to an 8-hour TWA of 85 dBA or greaters.Hearing protectors shall be made available and shall be worn by all employees exposed to an 8-hour TWA of 85 dBA or greaters. Types of hearing protectors:Types of hearing protectors: Ear muffsEar muffs Ear plugsEar plugs Ear canalEar canal

35. 10/1/9934 EarmuffsEarplugsCanal Caps Examples of Hearing Protectors

36. 10/1/9935 Hearing Protection NRR - Noise reduction rating –Express - 25 NRR –Classic - 29 NRR –Max Lite - 30 NRR DO NOT Subtract the NRR from the noise level –WRONG (109 dB - 25 NRR = 84 dB) You must use the “Safety Factor”

37. 10/1/9936 Safety Factor OSHA says the hearing protection is designed to reduce the noise by the NRR, but that is unlikely to happen due to : –Leaks in the seal –Vibration –Improper insertion (NRR - 7)

38. 10/1/9937 Example of NRR Protection The noise at a large compressor is 109 dB You are wearing the Express plugs with an NRR of 25 Do you have enough protection to place you below 90 dB level?

39. 10/1/9938 Training - Recordkeeping Employees training is very important. All employees exposed to noise at a TWA of 85 dBA or greater shall participate in a hearing conservation training program.Employees training is very important. All employees exposed to noise at a TWA of 85 dBA or greater shall participate in a hearing conservation training program. An accurate records shall maintained of all employee exposure measurements.An accurate records shall maintained of all employee exposure measurements.