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Occupational Hearing Loss, Hearing Handicaps and Presbycusis

Hearing Handicap Calculator
Presbycusis Calculator - Robinson Sutton and Spoors Equations
Age Projection Calculator


 About Presbycusis

Noise Induced Hearing Loss

About NIOSH Calculator

Total Body Handicap

Formula Table

This website is devoted to the evaluation of occupational hearing loss.  The most common cause of occupational hearing loss is acoustic trauma from loud noise.  The determination of hearing impairment is often based upon the American Academy of Otolaryngology 1979 equation.  There are many other different equations which can be used to calculate hearing impairment.  They vary between federal agencies, states, and countries.  Most USA courts now recognize the AAO 1979 formula, and its use has been successfully argued in many legal settings (Byrum v. Newport News Shipbuilding & Dry Dock Co., 14 B.R.B.S. 833 [1982]).

             ** Go To Master Calculator  ** 

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Maximum Recommended Noise Exposure
  NIOSH 1997 and ACGIH 

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Maximum Recommended Noise Exposure
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The Hearing Impairment Calculator and Master Calculator can be used to determine the degree of hearing impairment present.  Once the level of hearing impairment has been determined, a table is used to identify the total body handicap percentage **  See Total Body Handicap Table ***       


When evaluating cases of occupational hearing loss, one must distinguish between Medical and Legal Causation.   Medical Causation calls for scientific certainty, but Legal Causation only needs to be within a reasonable degree of medical certainty.  In some settings, only a more likely than not or greater than 50% likelihood is needed.

Presbycusis is hearing loss associated with aging.  In the medical-legal context, it is the "non-occupational" hearing loss, or "nosocusis" as described by Kryter in 1983, which the average individual of a certain age has.  Compensation for presbycusis may be performed when evaluating occupational hearing losses.  Go To Presbycusis Calculator

Often workers have a preexisting hearing loss when they begin employment.  Many years later, upon retirement, the hearing loss is worse and the question is raised:  Is the worker's hearing loss at retirement due to added occupational noise exposure, or is it just the combination of the worker's pre-employment hearing loss and other environmental factors.  The Age Projection Calculator or Master Calculator can give guidance to this question.  This calculator can also be used to project the worker's post-employment audiogram into the future and determine the likely hearing impairment at any given age.  (The Master Calculator and Age Projection Calculators will determine the degree of presbycusis in the initial audiogram.  Subtract these values from the presbycusis for the projected age; then add the difference to the thresholds in the initial audiogram, thus, calculating the projected audiogram.  All projected thresholds are also off-set by the ISO-1999 compression factor and truncated at 100 dB.)

Master Impairment and Projection Calculator
This calculator can use Robinson-Sutton's or Spoor's Presbycusis Equations. 
In addition, there are seven impairment formulas to choose from.
View:    Formula Definitions      More About Presbycusis

 Hearing Impairment Calculators
(AAO 1979- Reference: JAMA 241:2055-2059,1979)

  Frequencies Low Fence High Fence Better Ear Ratio
AAO 1979 500, 1000, 2000, 3000 25 92 5 : 1
AAOO 1959 500, 1000, 2000 25 92 5 : 1
1000, 2000, 3000 25 92 5 : 1
See About Calculator
1000, 2000, 3000, 4000 25 92 5 : 1




Presbycusis Calculator  

bulletRobinson Sutton Equations
(Reference: Robinson, DW and Sutton, GJ. Audiology 18:320-334,1979.  
As also described in Annex A of ISO 1999-01-15)
bulletSpoor's Equations:
(Spoor, A, Int. Audiology 6:48-57,1967)


Age Projection of Audiogram
(Noise induced hearing loss and presbycusis are assumed to be additive.

--Macrae, JH. Audiology. 10:323-333,1971. 
All thresholds are off-set by ISO-1999 Compression Factor for adding 
presbycusis and noise induced hearing loss)



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The maximum recommended noise exposure, impairment, projection, presbycusis and master calculators are meant for educational use.  The user accepts these web-based calculators "AS IS" without warranty of any kind. The user also assumes all responsibility for the testing of the calculators and any loss or liability caused directly or indirectly by the calculators' use. Cumberland Otolaryngology Consultants, Dr. Kevin T. Kavanagh and/or their employees, associates and/or stockholders assume NO liability (direct, indirect or incidental) related to the calculators operation.

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