3M eg4 Criterion Time, Decibel dB, Dose, Exchange Rate ER also known as the Doubling Rate

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Appendix B

Glossary of Terms

Criterion Time

The time over which the Criterion Level is established, generally 8 hours.

Decibel (dB)

Sound Level Meters use the decibel as the unit of measure known as Sound Pressure Level (SPL). SPL uses the ratio between a reference level of 20 microPascals (.00002 Pascals) and the level being measured. SPL = 20 log (measured level/reference level). Example: the SPL for 1 Pascal is 20 log (1 Pascal/.00002 Pascal) = 94dB 20 microPascals (.00002 Pascals) is considered the average threshold of hearing. A whisper is about 20 dB. A normal conversation is typically from 60 to 70 dB, and a noisy factory from 90 to 100 dB. Loud thunder is approximately 110 dB, and 120 dB borders on the threshold of pain.

Dose

Related to the Criterion Level, a dose reading of 100% is the maximum allowable exposure to accumulated noise. For OSHA, 100% dose occurs for an average sound level of 90 dB over an 8 hour period (or any equivalent exposure). By using a TWA reading rather than the average sound level, the time period is no longer explicitly needed. A TWA of 90 dB is the equivalent of 100% dose. The dose will double (halve) every time the TWA increases (decreases) by the Exchange Rate. Example: OSHA uses an Exchange Rate of 5 dB. Suppose the TWA is 100 dB. The dose would double for each 5 dB increase over the Criterion Level of 90 dB. The resulting dose is therefore 400%. If the TWA was instead equal to 80 dB then the dose would halve for each 5 dB below the Criterion Level. The resulting dose would be 25%. When taking noise samples less that the full workday, dose is an easy number to work with because it is linear with respect to time. Example: If a 0.5-hour sample results in 9% dose and the workday is 7.5 hours long, then the dose for the full workday would be a 135% dose (7.5 / 0.5 x 9%). This is computed making the assumption that the sampled noise will continue at the same levels for the full 7.5-hour workday.

Exchange Rate (ER – also known as the Doubling Rate)

Exchange rate refers to how the sound energy is averaged over time. Using the decibel scale, every time the sound energy doubles, the measured level increases by 3dB. This is the 3dB exchange rate that most of the world uses. For every increase of 3dB in the time weighted average, the measured DOSE would double. Some organizations such as OSHA in the U.S. have argued that the human ear self compensates for changing noise levels and they felt that the 3dB exchange rate should be changed to more closely match the response of the human ear. OSHA currently uses a 5dB exchange rate, which would mean that the reported DOSE would double with every 5dB increase in the time weighted average. The exchange rate affects the integrated reading LAVG, DOSE, and TWA but does not affect the instantaneous sound level.

053-644, Rev H

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Contents Edge 3M The Edge Personal Noise DosimeterTable of Contents Setting-up the Edge via DMS Time history……………………………………………………………………………………………………Technical Support Stopping a studyViewing measurements on the display Replacing microphone and windscreenPhysical attributes of EdgeDock1 and EdgeDock5 INDEX…………………………………………………………………………………List of Figures List of TablesDosimetry Edge and dosimetryNoise dosimeter Illustration of how the dosimeter operates and processesRange of sound What do the standards say?Applications of the Edge Running your studies Setting-up your dosimeter parameters for your noise studiesNoise assessment steps View your results via DMSParameter setup screen for eg4 Edge ModelChecking the equipment Identifying your equipmentLED indicator Turning onLED indicators explained Turning offDiagram Display and keypad3MTMDetection Mangement Software DMS Docking station functionalityLoading Docking station components EdgeDock1 or EdgeDock5EdgeDock1 and EdgeDock5 components Powering EdgeDock1 or EdgeDock5  Powering EdgeDock1 or EdgeDock5 How to charge Charging your dosimeterMounting the docking station to a wall Storing the dosimeterUnderstanding what data is stored Noise studiesSummary data Time historyViews on the Edge LoggingDefinitions of data log values and views Views on ExplanationDosimeter views and definitions Dose WeightingViews on Explanation Edge Response LevelDescriptors Variants Lmax variants Dosimeter measurement descriptors/variantsDocking Communicating & downloading dataCustomizing set-up parameters in DMS New Hardware wizard for Edge DockDosimeter setting Dosimeter screenEdge dosimeter settings Dosimeter fields explained for the EdgeDisplay setting Edge display screenSecurity setting Edge security settingAuto Run setting Edge auto run screenFirmware update 10 Edge firmware update screenSaving and sending/setting configurations 11 Saving and sending Edge setupsOverview of running a study Quick Help List typical dosimetry sessionWindscreen and maintenance  How to attach the dosimeterPositioning the Edge on your shirt Checking battery power  Checking battery powerCalibrating  Calibrating the dosimeterResetting the dosimeter  ResetSetting contrast on dosimeter  ContrastOn/off/enter button  How to run a noise study Running studiesStarting a run Indicator Icon Explanation Indicators/Icons on the display How to stop a noise study Indicators i.e., run, stop, battery, and OLViewing measurements on the display Locking or securing your dosimeter during run Viewing measurements Locking or Securing  How to lock or secure How to unlock UnlockingDownloading data  DownloadingDMS start screen Viewing data and data finder  Selecting and viewing dataReport View Example of Edge Report in DMSPanel Layout Viewcharts/graphs Panel layout view viewing the data in charts and graphsLED indicator disable/enable Technical SupportReplacing microphone and windscreen Attaching/Detaching Attaching/Detaching the windscreen and microphone Hard Hat Attachment Kit Hard Hat Attachment kitMechanical characteristics StandardsElectrical characteristics Environmental effectsUser Interface EdgeDock1 and EdgeDock5 Physical attributes of EdgeDock1 and EdgeDock5Measurements TypesMeasurement parameters Security CommunicationsSpecial functions Auto-RunEdge Block Diagram Edge Block Diagram Appendix B Service Department and Technical Support 1 800 3M ServiceWarranty Contacting 3MGlossary of Terms Background Noise, effectsCombining Noise sources Crest FactorCriterion Level CL Dose Criterion TimeDecibel dB Exchange Rate ER also known as the Doubling RateLavg Average Level Free field setting microphoneHearing Conservation HC Hertz Hz Lep,dMaximum Level Lmax Leq Equivalent LevelLogging Measurement RangeRandom incidence microphone PEL Permissible Exposure LevelProjected Time Response TimeTWA Time Weighted Average ThresholdWeighting A, C, Z, etc Upper Limit ULWindscreen Measurement equations Index Running studies About 3M Personal Safety About Us
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