1. Noise and hearing conservation Level 2 July 2007 / Marcel Buehrer

2. 2 Contents of this presentation 1. What is sound / noise – Some theorie and background 2. Health impact of noise 3. Which limits are valid 4. Noise measurement 5. Medical surveillance - Audiometry 6. Hearing protection 7. Suggestions to minimize health risk

3. 3 1. What is Sound / Noise? – Some theorie l Sound is a disturbance of mechanical energy that propagates through matter such as gases, liquids, solids, and plasmas as a wave. Sound is characterized by the properties of waves, which are frequency, wavelength, period, amplitude, and speed. l Humans perceive sound by the sense of hearing. By sound, we commonly mean vibrations that travel through air and are audible to people. l Noise can be defined as unwanted sound

4. 4 What is Sound / Noise? l The matter that supports the sound is called medium. Sound propagates as waves of alternating pressure, causing local regions of compression and rarefaction. The scientific study of sound is called acoustics. l Noise is often used to refer to an unwanted sound. In science and engineering, noise is an undesirable component that obscures a wanted signal.

5. 5 Speed of sound l The speed at which sound travels depends on the Medium through which the waves are passing, and is often quoted as a fundamental property of the material. l In air, the speed of sound is approximately 344 m/s, in water 1500 m/s and in a bar of steel 5000 m/s.

6. 6 Our ear can register tones, noise, and sounds via pressure differences in the air. Physically, noise is a pressure change which is registered by the ear. Perception of noise / sound

7. 7 l Humans can generally hear sounds with frequencies between 20 Hz and 20 kHz (20’000 Hz). l Most human speech communication takes place between 200 and 8’000 Hz and the human ear is most sensitive to frequencies around 1’000 - 3’500 Hz. Sound above the hearing range is known as ultrasound, and that below the hearing range as infrasound. l The amplitude of a sound wave is specified in terms of its pressure. The human ear can detect sounds with a very wide range of amplitudes and so a logarithmic decibel amplitude scale is used.

8. 8 outer ear middle ear inner ear eardrum ear duct ear lobe Eustachian tube Cross-section through the Hearing System

9. 9

10. 10 With a sound level meter, the sound pressure can be measured as sound level. The measuring unit is decibel (dB). Because the ear is not equally sensitive to all frequencies, a filter is set into the device which adjusts the measurement to the hearing. [dB(A)] The measuring unit decibel dB is within logarithmic scale. A difference of 3 dB means double loudness. Sound pressure / sound level

11. 11 Examples of Sound Level Values

12. 12 Further to know regarding sound Airborne soundContact sound Echo

13. 13 Noise is part of everyday life, but loud noise can permanently damage our hearing. Conversation becomes difficult or impossible, your family complains about the television being too loud and you have trouble using the telephone. Permanent tinnitus (ringing in the ears) can also be caused. The damage can be instant, for very loud or explosive noises, but generally it is gradual. By the time you notice it, it is probably too late. Hearing loss caused by work is a significant occupational disease. 2. Health impact of noise

14. 14 Auditory preceptor cells

15. 15 How loud is dangerous?

16. 16 How loud is harmful or distractive?

17. 17 l Noise reduces concentration and leads to earlier fatigue. l Stress and noise, especially in combination with shift work, can lead to sleep disorder. l Noise can lead to accidents if accoustic alarms are not heard. l Noise is also harmful to a worker’s unborn child. Impact of Noise – further facts

18. 18 Effects of Noise – even below the limits

19. 19 Extra-aural impactAural impact psychical reactions vegetative reactions hearing damage mechanical damage noise pressure level high blood pressure indigestion stress hearing difficulty visual disorder sleep disorder agressivity concentration disorder communication difficulty dB(A) 140 120 100 80 60 40 20 0 fear performance loss

20. 20 For ear protection, J&J and National legislations have set limit values. These are based on experiences for possible ear damage: limit for average stress (8 hours/day): limit J&J: 85 dB(A) action limit J&J:82 dB(A)  dosimetry limit for single event (shock / bang): 130 - 135 dB(C) For noise above the limit, protection is prescribed. For noise above the action limit, technical measures for noise reduction have to be evaluated. 3. Limit Values

21. 21 4. Noise Measurement sound level meter noise dosimeter Prior and after each measurement, the devices are calibrated against a standard source of sound.

22. 22 Field protocol for noise measurement

23. 23 The noise dosimeter is worn during a certain job. It measures the sound level continuously and records the data. Subsequently the average stress is calculated. Very important! The protocol has to be completed carefully and completely. Field protocol for dosimetry

24. 24 Dosimetry – place of the microphone For dosimetry it is essential to attach the microphone on the right place for avoidance of too high readings and therefore overestimations. right wrong because of possible echo

25. 25 Graph of the measured noise values

26. 26 82.1 dB (A) Calculation software for dosimetry

27. 27 5. Medical surveillance - Audiometry The individual ear capacity is tested in a low noise cabin with the aid of a pure tone audiometer and headphones. During the test, the testing tone level is increased or decreased in steps (3 dB). For the frequencies of 500 to 8000 Hz, for each ear the lowest still audible sound is determined. The results are shown in an audiogram.

28. 28 0 10 20 30 40 50 60 70 80 90 100 500100020003000400060008000 frequency [Hz] hear loss in decibel [dB] main language range 60 40 20 Audiogram with Ear Damage impact of an ear damage: loss of high tones loss in resolution capacity

29. 29 Various personal ear protection is available - 6. Hearing protection

30. 30 Nosie reduction rates of protection e.g. ear stoppers reduce sound up to 30 dB

31. 31 Proper Use of Ear Stoppers – Steps 1 and 2 1. Foam ear stoppers have to be shaped into a thin roll by pressing or turning with the fingertips prior to insertion into the ear duct. 2. The rolled ear stoppers has to be inserted immediately into the ear duct. Proper positioning with small diameter is ensured thus only.

32. 32 3. Ear stoppers can be inserted more easily by pulling of the ear. 4. After insertion into the ear duct, fix the stopper with the fingertip. 5. Fixation is to be continued until the stopper fits the ear duct completely (min. for 30 seconds, better for 1 – 2 min. resp. acc. to suppliers‘ specification). The protection factors resp. insulation values specified by the supplier are achieved by this procedure only! Proper Use of Ear Stoppers – Steps 3 to 5

33. 33 Right Wrong

34. 34 Advantage: Very comfortable and reliable Disadvantage: Expensive (+/- 120 € per person) Personally fitted Otoplasts

35. 35 Good maintenance is always necessary...

36. 36 7. Suggestions to minimize health risk SOP for Noise and Hearing Conservation: l Assess risks to develop an action plan l Reduce risks for all employees l Investigate and implement good practice and industry standards for control of noise l Prioritise higher risk cases with a programme of control measures l Use hearing protection for residual risks l Health surveillance to detect hearing damage and feedback to control measures

37. 37 Tools for estimating noise exposure Example to encourage rapid exposure determination, and Risk assessment

38. 38 Work-Flow

39. 39 Eliminate the source of noise The most efficient and effective way of controlling noise is by technical and Organisational, means that protect workers at source, eg. changes in process, reducing Vibration (damping) and reducing time spent in noisy areas.

40. 40 Practical example - 1 Replacement of old and loud agitation gears Before: > 80 dB(A) New gear and housing: +/- 70 dB(A)

41. 41 Practical example - 2 Silent vacuum pumps - placed in separate area

42. 42 Noise calculations – additions

43. 43 Noise calculations – averaging

44. 44 http://www.hse.gov.uk/noise/dailycalc.xls Noise calculations – time weighing

45. 45 l New devices and machines must not generate noise above 75 - 80 dB(A)! l For all old devices above 85 dB(A) a plan for noise reduction has to be established.  MAP l Over 85 dB(A): hearing protection is mandatory. room/machine is especially marked l 82- 84 dB(A): hearing protection is available, wearing is recommended. Short summary

46. 46 Noise stress 82 - 84 dB ear protection recommended When unit is working Labelling of noisy areas

47. 47 Early experiment of a Techno party

48. 48 ? Questions