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Noise Fundamentals

HOW DO WE HEAR?. SOUND RECEPTORS. DAMAGED HAIR CELLS. . High Sound Levels (Noise) can be Detrimental to Hearing, especially when exposure is for an extended period This is a fact and it is widely known and almost common knowledge, and yet, little is done to protect workers from the harmful effects of noise .

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Noise Fundamentals

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    2. HOW DO WE HEAR?

    3. SOUND RECEPTORS

    4. DAMAGED HAIR CELLS

    5. High Sound Levels (Noise) can be Detrimental to Hearing, especially when exposure is for an extended period This is a fact and it is widely known and almost common knowledge, and yet, little is done to protect workers from the harmful effects of noise

    6. Noise Induced Hearing Loss

    7. HOW CAN IT HAPPEN? One Time Exposure To Loud Sound OR Daily Exposures To Moderately Loud Sounds

    8. Why is there so little done to protect workers from noise?

    9. Noise is possibly annoying, but it is not physically painful

    12. Hearing protection might be regarded as a bother to many construction workers Workers may not know the sound level at work..

    13. Basic Information on Noise Should Be Understood

    14. Sound Fundamentals

    15. How Much Does the Sound Intensity Diminish with Distance from the Source?

    18. How much does the noise level actually decline with distance? The decline of 6db when the distance from the source is doubled is based on no encumbrances (e.g. no sound reflected from objects), but this is not the real world

    19. Testing of Construction Tools Common Construction Tools were Selected Sound was Measured in a Laboratory Setting Repeated Measures were Taken for Statistical Reliability

    21. Why Does the Sound not Decline as Computed? Sound is reflected from the concrete floor Sound is reflected from the block walls Sound is reflected from other objects

    22. Some Acceptable Levels of Noise Exposure have been Established

    23. Common Sound Levels Library 40 db Conversation (3ft) 70 db Garbage Disposal (3ft) 80 db Lawnmower (3ft) 100 db Concert 110 db Threshold of Pain 130 db

    24. Safety Regulations on Permissible Noise Exposure each day 8 hours 90 db 4 hours 95 db 2 hours 100 db 1 hour 105 db ˝ hour 110 db Ľ hour 115 db

    25. What Kinds of Noise Levels are Construction Workers Exposed to? This was explored in a study of power tools that are commonly used on construction projects Measured ~ 150 mm from the tool (not cutting) Max RPM

    30. Sound Levels of Tools when Running at Maximum RPM vs Cutting or Working on Wood

    31. Sound Intensity (db) of A Circular Saw at 600 mm (approx distance from the tool to the operator’s ear)

    32. Sound Intensity when a 2nd Noise Source is added Sound level of 1 saw 94.8 decibels Sound level of 2 saws 99.7 decibels Computed sound level of 2 saws 97.2

    33. Hearing Protection

    34. Hearing Protection

    37. DOUBLING UP! Use of insert earplugs and circumaural earmuffs together

    38. Conclusion Workers are probably exposed to higher levels of noise than would be predicted

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