Maico Slide-rule Hearing Loss Percentage Calculator
The Maico Percentage of Hearing Loss Calculator is
a plastic cardboard slide rule device made to calculate percent hearing
loss. (In truth, hearing loss is measured in decibels (dB) on an
open-ended logarithmic scale and thus cannot be expressed as a percentage.)
In order to determine the "percentage" of hearing
loss using the calculator, four cardboard sliders were moved to set
arrows under the measured dB loss at 500 Hz, 1000 Hz, 2000 Hz and 4000
Hz. The total "percentage" hearing loss is then read off on the bottom
scale of the slide rule. |
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There is also a scale on the reverse side to
determine what was called the Social Adequacy Index. This was done by
setting the hearing loss for speech (in decibels) computed from word
discrimination tests using phonograph and voice.
The only date on the slide is for one of the
references cited and is 1948. |
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The Maico Percentage Hearing
Loss Calculator in its protective envelope. |
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The Maico Percentage Hearing Loss Calculator with its protective
envelope. |
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The Maico
Percentage Hearing Loss Calculator protective envelope with instructions
for use. |
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An insert that shows how
to hold the Maico Percentage Hearing Loss Calculator when in use.
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