It’s All Noise Lee Hager, COHC 3M Lee Hager, COHC 3M © 3M All Rights Reserved.

Analysis Recordkeeping Education & Training Hearing Protection Audiometric Testing Admin. Controls Noise Controls Noise Monitoring Hearing Loss Prevention Hearing Loss Prevention— Simple, But Not Easy © 3M All Rights Reserved.

Risk Management Assess Risk Noise Exposure Assessment Mitigate Risk Noise Control Hearing Protection Assess Effect Hearing Testing Quality of program HERE drives … Integrity of program here. © 3M All Rights Reserved.

The Package  SL1.0 –Buy it Quiet  SL 2.0 –Assess Risk  SL 3.0 –Manage effect of noise  SL1.0 –Buy it Quiet  SL 2.0 –Assess Risk  SL 3.0 –Manage effect of noise © 3M All Rights Reserved.

Today’s Agenda  Better understanding of noise –Terminology –Physical Aspects –Decibels  Leads to better decisions about exposure  Better understanding of noise –Terminology –Physical Aspects –Decibels  Leads to better decisions about exposure © 3M All Rights Reserved.

Definitions: Sound or Noise  How about this?  Or this?  Trick question …  Bonus track  How about this?  Or this?  Trick question …  Bonus track 1.Keep ‘Em Coming, Alkaline Trio 2.Truck Song, Lyle Lovett 3.Donna Lee, Jaco Pastorius © 3M All Rights Reserved.

Describing Sound Physical Properties What We Hear Frequency in Hertz (Hz) Pitch Level in decibels (dB) Loudness Duration in hours Length © 3M All Rights Reserved.

Sound Frequency  Sound waves per second Hertz (Hz)  We hear a change in frequency as a change in pitch  Sound waves per second Hertz (Hz)  We hear a change in frequency as a change in pitch Low frequency— fewer waves per second High frequency— more waves per second © 3M All Rights Reserved.

Range of Human Hearing— Frequency  Greatest sensitivity to speech sounds ~250 Hz to 8000 Hz InfrasoundUltrasound Human hearing range 20 Hz20 kHz Hearing sensitivity Speech © 3M All Rights Reserved.

Frequency Response & Weighting “A” and “C” weighting curves © 3M All Rights Reserved.

Sound Level The sound pressure of painfully loud sounds is more than 10 million times greater than the sound pressure of the quietest sound we can hear! © 3M All Rights Reserved.

20 µPa 200,000,000µPa Threshold of hearing Threshold of pain Human hearing range Sound Pressure 0 dB 140 dB dB Range of Human Hearing - Level © 3M All Rights Reserved.

Loudness and SPL  Intensity/loudness –Decibel 1/10 of a Bel – an Alexander Graham Bell to be precise –1 dB barely audible –3 dB clearly audible –Energy 3 –Loudness 10 –Risk 3 or 4 or 5  Frequency –Measured in CPS –Expressed as hz –Middle C = 256 hz  Intensity/loudness –Decibel 1/10 of a Bel – an Alexander Graham Bell to be precise –1 dB barely audible –3 dB clearly audible –Energy 3 –Loudness 10 –Risk 3 or 4 or 5  Frequency –Measured in CPS –Expressed as hz –Middle C = 256 hz © 3M All Rights Reserved.

Sound Energy  Sound energy decreases over: –Time –Distance – the Inverse Square Law  Sound energy decreases over: –Time –Distance – the Inverse Square Law 1 meter 110 dBA 2 meters 104 dBA 4 meters 98 dBA © 3M All Rights Reserved.

Critical Noise Terminology Regulatory Issues  Criterion - The level at which 8 hours exposure would yield maximum allowable exposure, equivalent to PEL. –US OSHA 90 dB TWA  Threshold - The level below which all measured values are assigned a value of zero energy or contribution to dose. –US OSHA 80 dB  Criterion - The level at which 8 hours exposure would yield maximum allowable exposure, equivalent to PEL. –US OSHA 90 dB TWA  Threshold - The level below which all measured values are assigned a value of zero energy or contribution to dose. –US OSHA 80 dB © 3M All Rights Reserved.

Exposure = Noise*People*Time Exposure Time in Hours Allowable TWA using OSHA 5 dB Exchange Allowable TWA using 3 db Exchange 1105 dB99 dB 2100 dB96 dB 495 dB93 dB 890 dB 1685 dB87 dB 3280 dB84 dB © 3M All Rights Reserved.

Decibels Are Logarithmic  Exchange Rate (doubling, trading) – Increase (or decrease) in decibel level that results in a doubling (or halving) of exposure accumulation. –US OSHA 5 –Rest of world 3  Meaning – increase of 5 dB is DOUBLE the energy –DOUBLE the risk of hearing loss  Meaning – simple math does not work  Exchange Rate (doubling, trading) – Increase (or decrease) in decibel level that results in a doubling (or halving) of exposure accumulation. –US OSHA 5 –Rest of world 3  Meaning – increase of 5 dB is DOUBLE the energy –DOUBLE the risk of hearing loss  Meaning – simple math does not work © 3M All Rights Reserved.

Decibel Manipulation Example: Add 88, 85, 77, and 88 dB © Associates in Acoustics, Inc.  Formula method: L Pt = 92.1 dB © 3M All Rights Reserved.

Table Method Numerical difference between levels L P1 and L P2 (dB) L P3 : Amount to be added to the higher of L P1 or L P2 (dB) >100.0 for all practical purposes Simpler gross estimate 1.Calculate difference in levels 2.Add to higher value © Associates in Acoustics, Inc. © 3M All Rights Reserved.

Example Add 88, 85, 77, and 88 dB L P1 = 88 dB L P2 = 88 dB L P3 = 85 dB L P4 = 77 dB Step 1 – List each level from highest to lowest: © Associates in Acoustics, Inc. © 3M All Rights Reserved.

Table Method Example: Add 88, 85, 77, and 88 dB Numerical difference between levels L P1 and L P2 (dB) L P3 : Amount to be added to the higher of L P1 or L P2 (dB) > for all practical purposes L P1 = 88 dB L P2 = 88 dB L P3 = 85 dB L P4 = 77 dB Step 2 – Look up value to add to the higher number from table: Diff 0, add 3.0 = 91.0 Diff 6, add 1.0 = 92.0 Diff >10, add 0.0 = 92.0 dB = 92.0 dB From long form calc L Pt = 92.1 dB © Associates in Acoustics, Inc. © 3M All Rights Reserved.

Critical Noise Terminology Averages  Average Level (LAVG) - The level that if present continuously, would generate the same amount of energy as the varying levels that are present in the environment.  Equivalent Level (Leq) – As above, assuming 3 dB exchange rate and no threshold  Time Weighted Average (TWA) - A level average with an assumed fixed sample period of eight hours.  Action Level – Exposure at which hearing conservation program activity begins. –US OSHA 85 dB TWA or 50% dose.  Average Level (LAVG) - The level that if present continuously, would generate the same amount of energy as the varying levels that are present in the environment.  Equivalent Level (Leq) – As above, assuming 3 dB exchange rate and no threshold  Time Weighted Average (TWA) - A level average with an assumed fixed sample period of eight hours.  Action Level – Exposure at which hearing conservation program activity begins. –US OSHA 85 dB TWA or 50% dose. © 3M All Rights Reserved.

Dose  Dose - The daily exposure presented as a percentage of maximum allowable (100%). Dose is a function of sound level, time, criterion level, and exchange rate. As read from instrument, also function of measurement time.  Projected Dose – A “what if” dose calculation that assumes exposure conditions will continue as they were.  8 90 dB = 100% dose (noise PEL)  With 5 dB exchange –8 85 dB = 50% –16 85 dB = –8 95 dB = –12 90 dB =  Dose - The daily exposure presented as a percentage of maximum allowable (100%). Dose is a function of sound level, time, criterion level, and exchange rate. As read from instrument, also function of measurement time.  Projected Dose – A “what if” dose calculation that assumes exposure conditions will continue as they were.  8 90 dB = 100% dose (noise PEL)  With 5 dB exchange –8 85 dB = 50% –16 85 dB = –8 95 dB = –12 90 dB = © 3M All Rights Reserved.

Critical Noise Terminology Single Event  Maximum Level (Lmax) – The highest weighted slow level measured during sample period. –Pertains to ceiling level –US OSHA 115 dBA  Minimum Level (Lmin) – The lowest weighted slow level measured during sample period.  Peak Level (Lpk) The highest unweighted, fast response sound level measured during sample period. –US OSHA 140 dB  Response Time (fast or slow) – Indicates how the meter responds to changes in sound level. US OSHA uses slow –Equal amount of energy, distributed differently over time  Maximum Level (Lmax) – The highest weighted slow level measured during sample period. –Pertains to ceiling level –US OSHA 115 dBA  Minimum Level (Lmin) – The lowest weighted slow level measured during sample period.  Peak Level (Lpk) The highest unweighted, fast response sound level measured during sample period. –US OSHA 140 dB  Response Time (fast or slow) – Indicates how the meter responds to changes in sound level. US OSHA uses slow –Equal amount of energy, distributed differently over time © 3M All Rights Reserved.

Noise Happens Over Time Sound Level Time Fast response curve Slow response curve © 3M All Rights Reserved.

Exposure vs SL 1.0  SL 1.0 –No threshold –Msmt locations 1.5 m from floor1.5 m from floor 1 m from machine1 m from machine Include operator stationInclude operator station –Lavg not to exceed 80 dB at any location  SL 1.0 –No threshold –Msmt locations 1.5 m from floor1.5 m from floor 1 m from machine1 m from machine Include operator stationInclude operator station –Lavg not to exceed 80 dB at any location  SL 2.0 –80 dB threshold –Msmt locations Hearing zone of workerHearing zone of worker Task analysisTask analysis –TWA >= 85 HCPHCP HPD availableHPD available –TWA>= 90 HPD requiredHPD required EngineeringEngineering © 3M All Rights Reserved.

Thanks for Being Here…  It’s all noise  Better understanding makes for better decisions  Good luck!  It’s all noise  Better understanding makes for better decisions  Good luck! © 3M All Rights Reserved.