Subpart 1.
General.
For hearing loss, the maximum disability of the whole body is
35 percent. The procedures in subparts 2 to 7 shall be used to determine the
extent of binaural hearing loss and of whole body disability.
Subp. 2.
Medical diagnosis.
Otological evaluation shall be the method for determining the
degree of permanent partial hearing loss. The medical diagnosis shall include
the following:
A. A complete history
of occupational, military, and recreational noise exposure. This medical
history shall include documentation of any previous hearing loss, if that
information is available.
B. A
complete physical examination of the ear.
C. An audiological evaluation which shall
include pure tone air conduction and bone conduction testing.
Subp. 3.
Standards for
audiometric calibration and test environment.
To ensure accurate measurement of hearing loss, the following
standards shall be observed in conducting the tests required in subpart
2:
A. The audiometer used to measure
hearing loss shall be calibrated to meet the specifications of ANSI S3.6-1969
(R1973), Specifications for Audiometers. The following are also required:
(1) biological or electroacoustical
calibration checks of the audiometer shall be performed monthly;
(2) electroacoustical calibration shall be
performed annually to certify the audiometer to the ANSI standard in this item;
and
(3) the calibration records
shall be preserved and shall be provided upon request.
B. Audiometric test rooms or booths shall
meet the specifications of ANSI S3.1-1977, Criteria for Permissible Ambient
Noise during Audiometric Testing.
Subp. 4.
Waiting period for final
evaluation of hearing loss.
A waiting period of at least three months shall elapse between
the date of the occurrence of the noise injury and the final evaluation of the
permanent partial hearing loss.
Subp.
5.
Procedure for determining disability of whole body due to
hearing loss.
The binaural hearing loss is determined as follows:
A. The calculation for the percent of
binaural hearing loss consists of the following steps:
(1) For each ear, test the hearing threshold
levels at the four frequencies of 500, 1,000, 2,000, and 3,000 Hertz.
(2) For each ear, determine the average
four-frequency hearing level. The average four-frequency hearing level is
one-fourth of the sum of the threshold levels at each of the four tested
frequencies. The average four-frequency hearing level is expressed in
decibels.
(3) For each ear,
subtract 25 decibels from the average four-frequency hearing level for that
ear. The remainder, expressed in decibels, is the adjusted average
four-frequency hearing level.
(4)
For each ear, multiply the adjusted average four-frequency hearing level by 1.5
percent. The product is the monaural hearing loss, expressed as a percentage. A
product less than zero percent is deemed to be zero. A product greater than 100
percent is deemed to be 100 percent.
(5) Considering both ears, compare the
monaural hearing losses as determined in subitem (4). The ear with the smaller
monaural hearing loss is the better ear. The ear with the larger monaural
hearing loss is the poorer ear.
(6)
Multiply the monaural hearing loss of the better ear by five, add this product
to the monaural hearing loss of the poorer ear, and divide the sum by six. The
quotient is the binaural hearing loss, expressed as a percentage. The formula
is:
| (monaural hearing 5 x loss of better ear) |
+(monaural hearing loss of poorer ear) / 6 |
= percent binaural hearing loss |
B. The calculation of the percent of binaural
hearing loss is illustrated by the following examples.
Example 1
|
500 Hertz |
1,000 Hertz |
2,000 Hertz |
3,000 Hertz |
| Right ear |
15 |
25 |
45 |
55 |
| Left ear |
30 |
45 |
60 |
85 |
a. Calculation of
the average four-frequency hearing level:
| Right ear = |
15 + 25 + 45 + 55 / 4 |
= |
140 / 4 |
= 35 decibels |
| Left ear = |
30 + 45 + 60 + 85 / 4 |
= |
220 / 4 |
= 55 decibels |
b.
Calculation of adjusted average four-frequency hearing level:
Right ear = 35 decibels - 25 decibels = 10 decibels;
Left ear = 55 decibels - 25 decibels = 30 decibels;
c. Calculation of monaural hearing
loss:
Right ear = 10 x 1.5% = 15%
Left ear = 30 x 1.5% = 45%
d. Calculation of binaural hearing loss:
| (15% x 5) + 45% / 6 |
= 20 percent binaural hearing loss |
Example 2
|
500 Hertz |
1,000 Hertz |
2,000 Hertz |
3,000 Hertz |
| Right ear |
20 |
25 |
30 |
35 |
| Left ear |
30 |
45 |
60 |
85 |
a. Calculation of
average four-frequency hearing level.
| Right ear = |
20 + 25 + 30 + 35 / 4 |
= 25 decibels |
| Left ear = |
30 + 45 + 60 + 85 / 4 |
= 55 decibels |
b.
Calculation of adjusted average four-frequency hearing level.
Right ear = 25 decibels - 25 decibels = 0 decibels
Left ear = 55 decibels - 25 decibels = 30 decibels
c. Calculation of monaural hearing
loss:
Right ear = 0 x 1.5 percent = 0
Left ear = 30 x 1.5 percent = 45 percent
d. Calculation of binaural hearing loss:
| (0% x 5) + 45% / 6 |
= 7.5 percent binaural hearing loss |
C. The binaural hearing loss is translated to
a percentage of disability of the whole body by the ear schedule set forth
below:
Ear Schedule
| Binaural Hearing Loss, Percent |
Disability of Whole Body, Percent |
|
|
| 0 - 1.7 |
0 |
| 1.8 - 4.2 |
1 |
| 4.3 - 7.4 |
2 |
| 7.5 - 9.9 |
3 |
| 10.0 - 13.1 |
4 |
|
|
| 13.2 - 15.9 |
5 |
| 16.0 - 18.8 |
6 |
| 18.9 - 21.4 |
7 |
| 21.5 - 24.5 |
8 |
| 24.6 - 27.1 |
9 |
|
|
| 27.2 - 30.0 |
10 |
| 30.1 - 32.8 |
11 |
| 32.9 - 35.9 |
12 |
| 36.0 - 38.5 |
13 |
| 38.6 - 41.7 |
14 |
|
|
| 41.8 - 44.2 |
15 |
| 44.3 - 47.4 |
16 |
| 47.5 - 49.9 |
17 |
| 50.0 - 53.1 |
18 |
| 53.2 - 55.7 |
19 |
|
|
| 55.8 - 58.8 |
20 |
| 58.9 - 61.4 |
21 |
| 61.5 - 64.5 |
22 |
| 64.6 - 67.1 |
23 |
| 67.2 - 70.0 |
24 |
|
|
| 70.1 - 72.8 |
25 |
| 72.9 - 75.9 |
26 |
| 76.0 - 78.5 |
27 |
| 78.6 - 81.7 |
28 |
| 81.8 - 84.2 |
29 |
|
|
| 84.3 - 87.4 |
30 |
| 87.5 - 89.9 |
31 |
| 90.0 - 93.1 |
32 |
| 93.2 - 95.7 |
33 |
| 95.8 - 98.8 |
34 |
|
|
| 98.9 - 100.0 |
35 |
Subp.
6.
Presbycusis.
The calculation of the binaural hearing loss shall not include
an additional adjustment for presbycusis.
Subp. 7.
Tinnitus.
No additional percentage of permanent partial disability for
hearing loss shall be allowed for tinnitus.
