Section 80.25. Loss of hearing.

  The department adopts the following standards for the determination and evaluation of noise induced hearing loss, other occupational hearing loss and accidental hearing loss:

(1)   Harmful noise. Hearing loss resulting from hazardous noise exposure depends upon several factors, namely, the overall intensity (sound pressure level), the daily exposure, the frequency characteristic of the noise spectrum and the total lifetime exposure. Noise exposure level of 90 decibels or more as measured on the A scale of a sound level meter for 8 hours a day is considered to be harmful.

(2)   Measurement of noise. Noise shall be measured with a sound level meter which meets ANSI standard 1983 and shall be measured on the "A" weighted network for "slow response." Noise levels reaching maxima at intervals of one second or less shall be classified as being continuous. The measurement of noise is primarily the function of acoustical engineers and properly trained personnel. Noise should be scientifically measured by properly trained individuals using approved calibrated instruments which at the present time include sound level meters, octave band analyzers and oscilloscopes, the latter particularly for impact-type noises.

(3)   Measure of hearing acuity. The use of pure tone air and bone conduction audiometry performed under proper testing conditions is recommended for establishing the hearing acuity of workers. The audiometer should be one which meets the specifications of ANSI standard 53.6-1969 (4). The audiometer should be periodically calibrated. Preemployment records should include a satisfactory personal and occupational history as they may pertain to hearing status. Otological examination should be made where indicated.

(4)   Formula for measuring hearing impairment. For the purpose of determining the hearing impairment, pure tone air conduction audiometry is used, measuring all frequencies between 500 and 6,000 Hz. This formula uses the average of the 4 speech frequencies of 500, 1,000, 2,000, and 3,000 Hz. Audiometric measurement for these 4 frequencies averaging 30 decibels or less on the ANSI calibration does not constitute any practical hearing impairment. A table for evaluating hearing impairment based upon the average readings of these 4 frequencies follows below. No deduction is made for presbycusis.

(5)   Diagnosis and evaluation. The diagnosis of occupational hearing loss is based upon the occupational and medical history, the results of the otological and audiometric examinations and their evaluation.

(6)   Treatment. There is no known medical or surgical treatment for improving or restoring hearing loss due to hazardous noise exposure. Hearing loss will be improved in non-occupational settings with the use of a hearing aid. Since a hearing aid relieves from the effect of injury the cost is compensable where prescribed by a physician.

(7)   Allowance for tinnitus. In addition to the above impairment, if tinnitus has permanently resulted due to work exposure, an allowance of 5% loss of hearing impairment for the affected ear or ears shall be computed.

(8)   Hearing impairment table. - See PDF for table

(9)   Method for determining percent of hearing impairment.

(a) Obtain for each ear the average hearing level in decibels at the 4 frequencies, 500, 1,000, 2,000 and 3,000 Hz.

(b) See Table for converting to percentage of hearing impairment in each ear.

(c) To determine the percentage of impairment for both ears, multiply the lesser loss by 5, add the greater loss and divide by 6. Following are examples of the calculation of hearing loss: - See PDF for table

1. Calculation of average hearing threshold level - See PDF for diagram :

2. Calculation of hearing handicap:

Smaller number (better ear)

8% 5 = 40

Larger number (poorer ear)

40% 1 = 40

Total 80 B 6 = 13.33% loss

Therefore, a person with the hearing threshold levels shown in this audiogram would have a 13.33% hearing handicap. - See PDF for table

1. Average hearing threshold level: - See PDF for diagram

Therefore, the hearing loss is 4.8% left ear - See PDF for table

1. Average hearing threshold level (use 93 db maximal value) - See PDF for diagram :

2. Hearing handicap:

Smaller number (better ear)

88% 5 = 440

Larger number (poorer ear)

100% 1 = 100%

Total 540 6 = 90% loss

Therefore, the hearing handicap is 90%.

1-2-56 ; am. Register, January, 1960, No. 49 , eff. 2-1-60; am. Register, October, 1965, No. 118 , eff. 11-1-65; r. and recr. Register, September, 1972, No. 201 , eff. 10-1-72; am. (1) to (4), r. (5), renum. (6) and (7) to be (5) and (6), cr. (7) and am. (8), Register, September, 1975, No. 237 , eff. 10-1-75; am. (intro.), (2) to (4), (6), (8) and (9), Register, September, 1986, No. 369 , eff. 10-1-86.