Interview Question & Answer- Noise/Vibration

 

1. Q. Where is the best place to control noise? 
     A. At source. 

2. Q. What is a good way to reduce noise in machines ranging from power presses to typewriters etc? 
     A. Mount them on shock absorbers or special pads. 

3. Q. How would the noise from the cutting action of tools, circular saws etc. be reduced? 
     A. By keeping them sharp. 

4. Q. How could noise at one machine in a shop be reduced, without interfering with the machine itself? 

     A. Enclose it with sound absorbent material. 

5. Q. How could the noise in a boiler making shop be reduced? 
     A. By hanging such noise absorbing material as woollen blankets around the shop. 

6. Q. How can the ears be protected from noise? 

     A. By ear plugs, ear defenders, or muffs. 

7. Q. If there is a group of noisy machines, how could persons be protected from harmful effects in the short term? 
     A. Provide ear protection or use sound absorbing  material to enclose them. 

8. Q. What is the name for the unit of measurement of sound pressure level? 
     A. A decibel. 

9. Q. What do you understand by the term "Intensity of a Noise”? 
     A. The term intensity of a noise is a measure of the sound energy that vibrating air particles produced by the noise delivers to the ears. Sound intensity is measured in watts and converted to decibels (dB).

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10. Q. What do you understand by the term "Frequency of Noise”? 
       A. Frequency of a noise describes the rate of fluctuation of air particles produced by a noise. Frequency is measured in cycles per second (Hz).

11. Q. Give two factors that complicate the determination of hearing loss due to industrial exposure to noise? 
      A.  1. Medical History. 

           2. Exposure to excessive noise for up to 48 hrs. preceding test. 

12. Q. What is an Audiogram? 
       A. It is a measure of a person's ability over a range of frequencies, in relation to the threshold of hearing at which sound can be detected. 

13. Q. What is the Science of sound called? 
       A. Acoustics. 

14. Q. What is the name given to a sound level which has a frequency above the human ability to hear? 

       A. Ultrasound or Ultrasonic - (above 20,000Hz). 

15. Q. What is the name given to a sound level which has a frequency below the human ability to hear? 

       A. Infrasound or Infrasonic - (below 30Hz). 

16. Q. Name the two aspects of noise which are important in understanding noise hazards? 
       A.  1. Frequency. 
            2. Intensity. 

17. Q. What is meant by the terms:- Attenuation and Audiometry? 
       A. Attenuation - is reduction of transmitted  sound energy.  Audiometery - is the assessment of hearing capability. 

18. Q. What is the difference in use between a Sound Level Meter and an Audiometer? 
       A. A Sound Level Meter measures sound at the  workplace. An Audiometer measures an  individuals hearing ability. 

19. Q. In relation to noise what do the terms N.I.D. and N.I.H.L. stand for? 
       A.  1. Noise Induced Deafness. 
            2. Noise Induced Hearing Loss.

20. Q. What measurement on the decibel scale represents an increase or decrease of double or half the sound energy? 
       A. An increase or decrease of three decibels in sound energy. 

21. Q. How would you exclude outside noises when building a new building. Give four? 
       A.  1. Use cavity walls 
            2. Insulate cavities. 
            3. Insulate roof. 
            4. Line ceilings. 
            5. Double glaze. 
            6. Line walls. 

22. Q. What factors are important when choosing ear muffs for a person exposed to a noise hazard. Name four? 
       A.  1. Select the correct attenuation for the noise hazard. 

            2. The muffs should fit the wearer’s ears properly. 

            3. The muffs should be comfortable to wear. 
            4. It must be possible to wear safety glasses or spectacles if necessary. 

            5. The muffs should be free of defects. 

23. Q. Name four sound-absorbent materials? 
      A.  1. Glass wool. 
           2. Mineral wool. 
           3. Fabrics. 
           4. Acoustic Tiles. 
           5. Cork. 
           6. Paper. 

24. Q. How is noise transmitted in a workroom? 
       A. Through the air and the floor. 

25. Q. If a diesel driven compressor had to be used in a plant, what two points would you check on before allowing it to be used? 
      A.  1. That it had not increased the noise level 

               within the building to above the allowed

               level. 

           2. The exhaust gas was either piped outside

               or that the building was very well ventilated.

26. Q. What do you call the notional steady noise level which over a given period of time, would deliver the same amount of sound energy as the fluctuating level? 
       A. LEQ or Equivalent Continuous Sound Level. 

27. Q. If you were 2 metres from somebody and found it necessary to shout to communicate. What would you expect the minimum noise level present to be? 
       A. At least 85 dBA. 

28. Q. When people talk about the Noise Regulations what legislation are they referring to? 
       A. The Safety, Health and Welfare at Work (General Application) Regulations 2007 Chapter 1 of Part 5 – Control of Noise at Work. 

29. Q. According to current Health and Safety legislation and guidance how often should noise measurements be repeated and when? 
      A. At appropriate intervals, particularly when:- 

          •   Any significant change in work patterns. 

          •   Any significant change in equipment. 

30. Q. What factors should be considered in the cause of noise induced hearing loss? 
       A. An employer should look at both of the 

           following: 

           •   The level of noise 

           •   The length of time of exposure. 

31. Q. What is the daily noise exposure level? 
       A. This is the time–weighted average (TWA) of the noise level which an employee is exposed  to for a nominal eight hour working day,  which is defined by an international standard ISO. 

32. Q. If the daily noise exposure varies from one working day to the next, what may employers use to assess the levels of noise to which an employee may be exposed to? 
       A. Employers may use a weekly noise exposure level.

33. Q. Who should health surveillance be made available to? 
      A. Health surveillance should be made available to employees whose risk assessment revealed a risk to their health. 

34. Q. What should an employer do if an employee is found to have hearing damage as a result of exposure to noise at work? 
      A. The employer should review the risk assessment and the control measure provided to eliminate or reduce risks. 

35. Q. When would ear protectors be suitable and adequate? 
       A. Ear protectors are only suitable and adequate,  if and when properly worn; they will reduce  the level of noise experienced by the employee to a level below 80 dB(A). 

36. Q. What is the transitional period for the noise regulations for sea-going vessels? 
       A. Current Health and Safety legislation and 

            guidance (conducting risk assessment and 

            implementing controls) give an application 

            date of 15 February 2011. 

37. Q. Where can the Vibration Regulations be found? 
       A. The Safety, Health and Welfare at Work 

            (General Application) Regulations 2007 

            Chapter 2 of Part 5 – Control of Vibration 

            at Work. 

38. Q. Regulation 142 the Safety, Health and Welfare at Work (General Application) Regulations 2007 Chapter 2 of Part 5 – Control of Vibration at Work, permits for certain exemptions to the regulations, Who grants these exemptions and how? 
      A. Health & Safety Authority – by certificate 

           in writing. 

39. Q. What is meant by HAV, explain? 
       A. “Hand arm Vibration” means mechanical 

             vibration that, when transmitted to the 

             human hand-arm system, entails risks to 

             the safety and health of employees, in 

             particular vascular, bone or joint, 

             neurological or muscular disorders. 

40. Q. What is meant by WBV, explain? 
       A. “Whole body Vibration” means mechanical 

              vibration that, when transmitted to the 

              whole body, entails risks to the safety and

              health of employees, in particular lower- 

              back morbidity and trauma of the spine.

41. Q. Above how many dBA must an employer assess the level of noise an employee is liable to be exposed to and (2) What two conditions apply to these measurements under the Safety, Health and Welfare at Work (General Application) Regulations 2007 Chapter 1 of Part 5 – Control of Noise at Work 

       A. • Above 80 dBA. 

           • The measurements must be properly 

              planned. 

           • They must be carried out by a competent 

              person. 

42. Q. According to the Safety, Health and Welfare at Work (General Application) Regulations 2007 Chapter 1 of Part 5 – Control of Noise at Work an employer has a duty to reduce the level of noise exposure in the workplace to the lowest level reasonably practicable. Give three instances how this may be achieved? 
      A. 1. Ensuring new machinery has a low noise 

               output. 
          2. Install machinery so as to ensure noise 

              abatement. 
          3. Reducing the number of people working
              in a noisy area. 
          4. Reducing the length of exposure time. 
          5. Ensuring workplace structure and layout 

              contributes to noise abatement. 

43. Q. What are exposure action values in relation to noise? 
       A. These are the daily noise exposure level or 

            the peak sound pressure level which, if 

            exceeded, for an employee, action will 

            need to be taken to reduce the risk. These

            relate to: 

            • The levels of exposure to noise of your 

              employees averaged over a working day 

              or week. 

            • The maximum noises (peak sound pressure) 

               to which employees are exposed in a 

               working day. 

44. Q. What are Lower exposure action values? 
       A. Lower exposure action values: 

            • Daily or weekly exposure of 80 dB(A) 

            • Peak sound pressure of 135 dB (C). 

45. Q. What are Upper exposure action values? 
      A. Upper exposure action values: 

           • Daily or weekly exposure of 85 dB(A); 

           • Peak sound pressure of 137 dB(C ).

46. Q. Do the Safety, Health and Welfare at Work (General Application) Regulations 2007 Chapter 1 of Part 5 – Control of Noise at Work? apply to all workers? 
       A. The regulations apply to all workers and 

            workplaces except – 

            • Crew members at sea or in air transport 

               until February 2011. 

47. Q. What is a competent person with regard to the noise regulations. Give three requirements? 
       A. A competent person is someone: 

           • With knowledge and understanding of the 

              Noise Regulations 2006 

           • Who has the ability to use the correct 

              measurement equipment. 

           • Who can record and interpret the results 

              obtained in accordance with the 

              regulations. 

           • Who can make suitable and appropriate 

              recommendations on how the noise levels 

              can be reduced and so reduce the risk of 

              hearing damage occurring. 

48. Q. How long should noise records be kept, and to whom should they be available? 
       A. These records should be kept for 10 years and

            be available to 

            • The worker concerned or his/her 

               representative. 

            • The Inspectors of the Health and Safety 

               Authority. 

49. Q. What is the purpose of audiometric testing? 
       A. The purpose of Audiometric testing is:- 

            • To provide an early diagnosis of any hearing

               loss due to noise. 

            • To assist in the preservation of hearing. 

            • It can also provide a baseline of hearing at a

              specific time (before an employee starts 

              work with a particular employer). 

50. Q. Is the employer responsible to supply ear protection, elaborate? 
       A. Regulation 129 of the The Safety, Health and

            Welfare at Work (General Application) 

             Regulations 2007 Chapter1 of Part 5 – Control

             of Noise at Work states that where risks 

              arising from noise exposure:-            

             •  Can not be prevented by any other means. 

             •  The employer must supply sufficient 

                numbers of suitable ear protectors. 

             • Consulting with the workers regarding 

                suitability and adequacy of the type chosen.

51. Q. Should any form of music be used to block out a noisy workplace, explain your answer? 
       A. NO:- • In order to hear music in a noisy

                       workplace, it has to be played at a

                       level 10-15 dBA over any background

                       noise. 

                     • This means that the music itself

                        becomes the major source of noise 

                        exposure in the workplace. 

                     • This also applies to personal music

                        systems such as walkmans as well 

                        as any music being played over

                        loudspeakers. 

52. Q. What are the Exposure Limit Values and Action Values for hand-arm vibration expressed in Regulation 135 the Safety, Health and Welfare at Work (General Application) Regulations 2007 Chapter 2 of Part 5 – Control of Vibration at Work? 
       A.  • The daily exposure limit value standardised 

               to an eight-hour reference period shall be 

               5m/s2, 

            • The daily exposure action value 

               standardisedto an eight-hour 

               reference period shall be 

               2.5 m/s2. 

53. Q. What are the Exposure Limit Values and Action Values for whole body vibration expressed in Regulation 135 of the Safety, Health and Welfare at Work (General Application) Regulations 2007 Chapter 2 of Part 5 – Control of Vibration at Work of the vibration regulations? 
      A. • The daily exposure limit value standardised

              to an eight-hour reference period shall be 

             1.15 m/s2, 

           • The daily exposure action value standardised

              to an eight-hour reference period shall be

              0.5 m/s2.