(b)(1) When employees are subjected to sound exceeding those
listed in Table G-16, feasible administrative or engineering controls shall be utilized.
If such controls fail to reduce sound levels within the levels of Table G-16, personal
protective equipment shall be provided and used to reduce sound levels within the levels
of the table.
(b)(2) If the variations in noise level involve maxima at
intervals of 1 second or less, it is to be considered continuous.
TABLE G-16 - PERMISSIBLE NOISE EXPOSURES (1)
______________________________________________________________
|
Duration per day, hours | Sound level dBA slow response
____________________________|_________________________________
|
8...........................| 90
6...........................| 92
4...........................| 95
3...........................| 97
2...........................| 100
1 1/2 ......................| 102
1...........................| 105
1/2 ........................| 110
1/4 or less................| 115
____________________________|________________________________
Footnote(1) When the daily noise exposure is composed of two or
more periods of noise exposure of different levels, their combined
effect should be considered, rather than the individual effect of
each. If the sum of the following fractions: C(1)/T(1) + C(2)/T(2)
C(n)/T(n) exceeds unity, then, the mixed exposure should be
considered to exceed the limit value. Cn indicates the total time of
exposure at a specified noise level, and Tn indicates the total time
of exposure permitted at that level. Exposure to impulsive or impact
noise should not exceed 140 dB peak sound pressure level.
(c) "Hearing conservation program."
(c)(1) The employer shall
administer a continuing, effective hearing conservation program, as described in
paragraphs (c) through (o) of this section, whenever employee noise exposures equal or
exceed an 8-hour time-weighted average sound level (TWA) of 85 decibels measured on the A
scale (slow response) or, equivalently, a dose of fifty percent. For purposes of the
hearing conservation program, employee noise exposures shall be computed in accordance
with appendix A and Table G-16a, and without regard to any attenuation provided by the use
of personal protective equipment.
(c)(2) For purposes of
paragraphs (c) through (n) of this section, an 8-hour time-weighted average of 85 decibels
or a dose of fifty percent shall also be referred to as the action level.
(d) "Monitoring."
(d)(1) When information
indicates that any employee's exposure may equal or exceed an 8-hour time-weighted average
of 85 decibels, the employer shall develop and implement a monitoring program.
(d)(1)(i) The sampling
strategy shall be designed to identify employees for inclusion in the hearing conservation
program and to enable the proper selection of hearing protectors.
(d)(1)(ii) Where
circumstances such as high worker mobility, significant variations in sound level, or a
significant component of impulse noise make area monitoring generally inappropriate, the
employer shall use representative personal sampling to comply with the monitoring
requirements of this paragraph unless the employer can show that area sampling produces
equivalent results.
(d)(2)
(d)(2)(i) All continuous, intermittent and impulsive sound
levels from 80 decibels to 130 decibels shall be integrated into the noise measurements.
(d)(2)(ii) Instruments used to measure employee noise
exposure shall be calibrated to ensure measurement accuracy.
(d)(3) Monitoring shall be repeated whenever a change in
production, process, equipment or controls increases noise exposures to the extent that:
(d)(3)(i) Additional employees may be exposed at or above
the action level; or
(d)(3)(ii) The attenuation provided by hearing protectors
being used by employees may be rendered inadequate to meet the requirements of paragraph
(j) of this section.
(e) "Employee notification." The employer shall
notify each employee exposed at or above an 8-hour time-weighted average of 85 decibels of
the results of the monitoring.
(f) "Observation of monitoring." The employer
shall provide affected employees or their representatives with an opportunity to observe
any noise measurements conducted pursuant to this section.
(g) "Audiometric testing program."
(g)(1) The employer shall establish and maintain an
audiometric testing program as provided in this paragraph by making audiometric testing
available to all employees whose exposures equal or exceed an 8-hour time-weighted average
of 85 decibels.
(g)(2) The program shall be provided at no cost to
employees.
(g)(3) Audiometric tests shall be performed by a licensed or
certified audiologist, otolaryngologist, or other physician, or by a technician who is
certified by the Council of Accreditation in Occupational Hearing Conservation, or who has
satisfactorily demonstrated competence in administering audiometric examinations,
obtaining valid audiograms, and properly using, maintaining and checking calibration and
proper functioning of the audiometers being used. A technician who operates microprocessor
audiometers does not need to be certified. A technician who performs audiometric tests
must be responsible to an audiologist, otolaryngologist or physician.
(g)(4) All audiograms obtained pursuant to this section
shall meet the requirements of Appendix C: "Audiometric Measuring Instruments."
(g)(5) "Baseline audiogram."
(g)(5)(i) Within 6 months of an employee's first exposure at
or above the action level, the employer shall establish a valid baseline audiogram against
which subsequent audiograms can be compared.
(g)(5)(ii) "Mobile test van exception." Where
mobile test vans are used to meet the audiometric testing obligation, the employer shall
obtain a valid baseline audiogram within 1 year of an employee's first exposure at or
above the action level. Where baseline audiograms are obtained more than 6 months after
the employee's first exposure at or above the action level, employees shall wearing
hearing protectors for any period exceeding six months after first exposure until the
baseline audiogram is obtained.
(g)(5)(iii) Testing to establish a baseline audiogram shall
be preceded by at least 14 hours without exposure to workplace noise. Hearing protectors
may be used as a substitute for the requirement that baseline audiograms be preceded by 14
hours without exposure to workplace noise.
(g)(5)(iv) The employer shall notify employees of the need
to avoid high levels of non-occupational noise exposure during the 14-hour period
immediately preceding the audiometric examination.
(g)(6) "Annual
audiogram." At least annually after obtaining the baseline audiogram, the employer
shall obtain a new audiogram for each employee exposed at or above an 8-hour time-weighted
average of 85 decibels.
(g)(7) "Evaluation of
audiogram."
(g)(7)(i) Each employee's annual audiogram shall be compared
to that employee's baseline audiogram to determine if the audiogram is valid and if a
standard threshold shift as defined in paragraph (g)(10) of this section has occurred.
This comparison may be done by a technician.
(g)(7)(ii) If the annual audiogram shows that an employee
has suffered a standard threshold shift, the employer may obtain a retest within 30 days
and consider the results of the retest as the annual audiogram.
(g)(7)(iii) The audiologist, otolaryngologist, or physician
shall review problem audiograms and shall determine whether there is a need for further
evaluation. The employer shall provide to the person performing this evaluation the
following information:
(g)(7)(iii)(A) A copy of the requirements for hearing
conservation as set forth in paragraphs (c) through (n) of this section;
(g)(7)(iii)(B) The baseline audiogram and most recent
audiogram of the employee to be evaluated;
Date of the last
acoustic or exhaustive calibration of the audiometer; and
(m)(2)(ii)(E) Employee's most recent noise exposure
assessment.
(m)(2)(ii)(F) The
employer shall maintain accurate records of the measurements of the background sound
pressure levels in audiometric test rooms.
(m)(3) "Record
retention." The employer shall retain records required in this paragraph (m) for at
least the following periods.
(m)(3)(i) Noise exposure measurement records shall be
retained for two years.
(m)(3)(ii) Audiometric test
records shall be retained for the duration of the affected employee's employment.
(m)(4) "Access to records." All records required
by this section shall be provided upon request to employees, former employees,
representatives designated by the individual employee, and the Assistant Secretary. The
provisions of 29 CFR 1910.20 (a)-(e) and (g)-
(m)(4)(i) apply to access to
records under this section.
(m)(5) "Transfer of
records." If the employer ceases to do business, the employer shall transfer to the
successor employer all records required to be maintained by this section, and the
successor employer shall retain them for the remainder of the period prescribed in
paragraph (m)(3) of this section.
(n) "Appendices."
(n)(1) Appendices A, B, C, D,
and E to this section are incorporated as part of this section and the contents of these
appendices are mandatory.
(n)(2) Appendices F and G to this section are informational
and are not intended to create any additional obligations not otherwise imposed or to
detract from any existing obligations.
(o) "Exemptions."
Paragraphs (c) through (n) of this section shall not apply to employers engaged in oil and
gas well drilling and servicing operations.
(p) "Startup date."
Baseline audiograms required by paragraph (g) of this section shall be completed by March
1, 1984.
[39 FR 23502, June 27, 1974, as amended at 46 FR 4161, Jan. 16, 1981; 46 FR 62845, Dec.
29, 1981; 48 FR 9776, Mar. 8, 1983; 48 FR 29687, June 28, 1983; 54 FR 24333, June 7, 1989;
61 FR 5507, Feb. 13, 1996; 61 FR 9227, March 7, 1996]
Appendix A - Noise Exposure Computation
This Appendix is Mandatory
I. Computation of Employee Noise Exposure
(1) Noise dose is computed using Table G-16a as follows:
(i) When the sound level, L, is constant over the entire work shift, the noise dose, D,
in percent, is given by: D=100 C/T where C is the total length of the work day, in hours,
and T is the reference duration corresponding to the measured sound level, L, as given in
Table G-16a or by the formula shown as a footnote to that table.
(ii) When the workshift noise exposure is composed of two or more periods of noise at
different levels, the total noise dose over the work day is given by:
D = 100 (C(1)/T(1) + C(2)/T(2) + ... + C(n)/T(n)),
where C(n) indicates the total time of exposure at a specific noise level, and T(n)
indicates the reference duration for that level as given by Table G-16a.
(2) The eight-hour time-weighted average sound level (TWA), in decibels, may be
computed from the dose, in percent, by means of the formula: TWA = 16.61 log(10) (D/100) +
90. For an eight-hour workshift with the noise level constant over the entire shift, the
TWA is equal to the measured sound level.
(3) A table relating dose and TWA is given in Section II.
TABLE G-16A
_________________________________________________
Reference
A-weighted sound level, L (decibel) duration,
T (hour)
_________________________________________________
80................................... 32
81................................... 27.9
82................................... 24.3
83................................... 21.1
84................................... 18.4
85................................... 16
86................................... 13.9
87................................... 12.1
88................................... 10.6
89................................... 9.2
90................................... 8
91................................... 7.0
92................................... 6.1
93................................... 5.3
94................................... 4.6
95................................... 4
96................................... 3.5
97................................... 3.0
98................................... 2.6
99................................... 2.3
100.................................. 2
101.................................. 1.7
102.................................. 1.5
103.................................. 1.3
104.................................. 1.1
105.................................. 1
106.................................. 0.87
107.................................. 0.76
108.................................. 0.66
109.................................. 0.57
110.................................. 0.5
111.................................. 0.44
112.................................. 0.38
113.................................. 0.33
114.................................. 0.29
115.................................. 0.25
116.................................. 0.22
117.................................. 0.19
118.................................. 0.16
119.................................. 0.14
120.................................. 0.125
121.................................. 0.11
122.................................. 0.095
123.................................. 0.082
124.................................. 0.072
125.................................. 0.063
126.................................. 0.054
127.................................. 0.047
128.................................. 0.041
129.................................. 0.036
130.................................. 0.031
______________________________________________
In the above table the reference duration, T, is computed by
where L is the measured A-weighted sound level.
II. Conversion Between "Dose" and "8-Hour Time-Weighted Average"
Sound Level
Compliance with paragraphs (c)-(r) of this regulation is determined by the amount of
exposure to noise in the workplace. The amount of such exposure is usually measured with
an audiodosimeter which gives a readout in terms of "dose." In order to better
understand the requirements of the amendment, dosimeter readings can be converted to an
"8-hour time-weighted average sound level." (TWA).
In order to convert the reading of a dosimeter into TWA, see Table A-1, below. This
table applies to dosimeters that are set by the manufacturer to calculate dose or percent
exposure according to the relationships in Table G-16a. So, for example, a dose of 91
percent over an eight hour day results in a TWA of 89.3 dB, and, a dose of 50 percent
corresponds to a TWA of 85 dB.
If the dose as read on the dosimeter is less than or greater than the values found in
Table A-1, the TWA may be calculated by using the formula: TWA = 16.61 log(10) (D/100) +
90 where TWA=8-hour time-weighted average sound level and D = accumulated dose in percent
exposure.
TABLE A-1 - CONVERSION FROM "PERCENT NOISE EXPOSURE"
OR "DOSE" TO "8-HOUR TIME-WEIGHTED
AVERAGE SOUND LEVEL" (TWA)
______________________________________________
Dose or percent noise exposure TWA
______________________________________________
10 ............................. 73.4
15 ............................. 76.3
20 ............................. 78.4
25 ............................. 80.0
30 ............................. 81.3
35 ............................. 82.4
40 ............................. 83.4
45 ............................. 84.2
50 ............................. 85.0
55 ............................. 85.7
60 ............................. 86.3
65 ............................. 86.9
70 ............................. 87.4
75 ............................. 87.9
80 ............................. 88.4
81 ............................. 88.5
82 ............................. 88.6
83 ............................. 88.7
84 ............................. 88.7
85 ............................. 88.8
86 ............................. 88.9
87 ............................. 89.0
88 ............................. 89.1
89 ............................. 89.2
90 ............................. 89.2
91 ............................. 89.3
92 ............................. 89.4
93 ............................. 89.5
94 ............................. 89.6
95 ............................. 89.6
96 ............................. 89.7
97 ............................. 89.8
98 ............................. 89.9
99 ............................. 89.9
100 ............................ 90.0
101 ............................ 90.1
102 ............................ 90.1
103 ............................ 90.2
104 ............................ 90.3
105 ............................ 90.4
106 ............................ 90.4
107 ............................ 90.5
108 ............................ 90.6
109 ............................ 90.6
110 ............................ 90.7
111 ............................ 90.8
112 ............................ 90.8
113 ............................ 90.9
114 ............................ 90.9
115 ............................ 91.1
116 ............................ 91.1
117 ............................ 91.1
118 ............................ 91.2
119 ............................ 91.3
120 ............................ 91.3
125 ............................ 91.6
130 ............................ 91.9
135 ............................ 92.2
140 ............................ 92.4
145 ............................ 92.7
150 ............................ 92.9
155 ............................ 93.2
160 ............................ 93.4
165 ............................ 93.6
170 ............................ 93.8
175 ............................ 94.0
180 ............................ 94.2
185 ............................ 94.4
190 ............................ 94.6
195 ............................ 94.8
200 ............................ 95.0
210 ............................ 95.4
220 ............................ 95.7
230 ............................ 96.0
240 ............................ 96.3
250 ............................ 96.6
260 ............................ 96.9
270 ............................ 97.2
280 ............................ 97.4
290 ............................ 97.7
300 ............................ 97.9
310 ............................ 98.2
320 ............................ 98.4
330 ............................ 98.6
340 ............................ 98.8
350 ............................ 99.0
360 ............................ 99.2
370 ............................ 99.4
380 ............................ 99.6
390 ............................ 99.8
400 ............................ 100.0
410 ............................ 100.2
420 ............................ 100.4
430 ............................ 100.5
440 ............................ 100.7
450 ............................ 100.8
460 ............................ 101.0
470 ............................ 101.2
480 ............................ 101.3
490 ............................ 101.5
500 ............................ 101.6
510 ............................ 101.8
520 ............................ 101.9
530 ............................ 102.0
540 ............................ 102.2
550 ............................ 102.3
560 ............................ 102.4
570 ............................ 102.6
580 ............................ 102.7
590 ............................ 102.8
600 ............................ 102.9
610 ............................ 103.0
620 ............................ 103.2
630 ............................ 103.3
640 ............................ 103.4
650 ............................ 103.5
660 ............................ 103.6
670 ............................ 103.7
680 ............................ 103.8
690 ............................ 103.9
700 ............................ 104.0
710 ............................ 104.1
720 ............................ 104.2
730 ............................ 104.3
740 ............................ 104.4
750 ............................ 104.5
760 ............................ 104.6
770 ............................ 104.7
780 ............................ 104.8
790 ............................ 104.9
800 ............................ 105.0
810 ............................ 105.1
820 ............................ 105.2
830 ............................ 105.3
840 ............................ 105.4
850 ............................ 105.4
860 ............................ 105.5
870 ............................ 105.6
880 ............................ 105.7
890 ............................ 105.8
900 ............................ 105.8
910 ............................ 105.9
920 ............................ 106.0
930 ............................ 106.1
940 ............................ 106.2
950 ............................ 106.2
960 ............................ 106.3
970 ............................ 106.4
980 ............................ 106.5
990 ............................ 106.5
999 ............................ 106.6
___________________________________________
Appendix B - Methods for Estimating the Adequacy of Hearing
Protector Attenuation
This Appendix is Mandatory
For employees who have experienced a significant threshold shift, hearing protector
attenuation must be sufficient to reduce employee exposure to a TWA of 85 dB. Employers
must select one of the following methods by which to estimate the adequacy of hearing
protector attenuation.
The most convenient method is the Noise Reduction Rating (NRR) developed by the
Environmental Protection Agency (EPA). According to EPA regulation, the NRR must be shown
on the hearing protector package. The NRR is then related to an individual worker's noise
environment in order to assess the adequacy of the attenuation of a given hearing
protector. This appendix describes four methods of using the NRR to determine whether a
particular hearing protector provides adequate protection within a given exposure
environment. Selection among the four procedures is dependent upon the employer's noise
measuring instruments.
Instead of using the NRR, employers may evaluate the adequacy of hearing protector
attenuation by using one of the three methods developed by the National Institute for
Occupational Safety and Health (NIOSH), which are described in the "List of Personal
Hearing Protectors and Attenuation Data," HEW Publication No. 76-120, 1975, pages
21-37. These methods are known as NIOSH methods No. 1, No. 2 and No. 3. The NRR described
below is a simplification of NIOSH method No. 2. The most complex method is NIOSH method
No. 1, which is probably the most accurate method since it uses the largest amount of
spectral information from the individual employee's noise environment. As in the case of
the NRR method described below, if one of the NIOSH methods is used, the selected method
must be applied to an individual's noise environment to assess the adequacy of the
attenuation. Employers should be careful to take a sufficient number of measurements in
order to achieve a representative sample for each time segment.
NOTE: The employer must remember that calculated attenuation values reflect realistic
values only to the extent that the protectors are properly fitted and worn.
When using the NRR to assess hearing protector adequacy, one of the following methods
must be used:
(i) When using a dosimeter that is capable of C-weighted measurements:
(A) Obtain the employee's C-weighted dose for the entire workshift, and convert to TWA
(see appendix A, II).
(B) Subtract the NRR from the C-weighted TWA to obtain the estimated A-weighted TWA
under the ear protector.
(ii) When using a dosimeter that is not capable of C-weighted measurements, the
following method may be used:
(A) Convert the A-weighted dose to TWA (see appendix A).
(B) Subtract 7 dB from the NRR.
(C) Subtract the remainder from the A-weighted TWA to obtain the estimated A-weighted
TWA under the ear protector.
(iii) When using a sound level meter set to the A-weighting network:
(A) Obtain the employee's A-weighted TWA.
(B) Subtract 7 dB from the NRR, and subtract the remainder from the A-weighted TWA to
obtain the estimated A-weighted TWA under the ear protector.
(iv) When using a sound level meter set on the C-weighting network:
(A) Obtain a representative sample of the C-weighted sound levels in the employee's
environment.
(B) Subtract the NRR from the C-weighted average sound level to obtain the estimated
A-weighted TWA under the ear protector.
(v) When using area monitoring procedures and a sound level meter set to the A-weighing
network.
(A) Obtain a representative sound level for the area in question.
(B) Subtract 7 dB from the NRR and subtract the remainder from the A-weighted sound
level for that area.
(vi) When using area monitoring procedures and a sound level meter set to the
C-weighting network:
(A) Obtain a representative sound level for the area in question.
(B) Subtract the NRR from the C-weighted sound level for that area.
Appendix C - Audiometric Measuring Instruments
This Appendix is Mandatory
1. In the event that pulsed-tone audiometers are used, they shall have a tone on-time
of at least 200 milliseconds.
2. Self-recording audiometers shall comply with the following requirements:
(A) The chart upon which the audiogram is traced shall have lines at positions
corresponding to all multiples of 10 dB hearing level within the intensity range spanned
by the audiometer. The lines shall be equally spaced and shall be separated by at least
1/4 inch. Additional increments are optional. The audiogram pen tracings shall not exceed
2 dB in width.
(B) It shall be possible to set the stylus manually at the 10-dB increment lines for
calibration purposes.
(C) The slewing rate for the audiometer attenuator shall not be more than 6 dB/sec
except that an initial slewing rate greater than 6 dB/sec is permitted at the beginning of
each new test frequency, but only until the second subject response.
(D) The audiometer shall remain at each required test frequency for 30 seconds (+ or -
3 seconds). The audiogram shall be clearly marked at each change of frequency and the
actual frequency change of the audiometer shall not deviate from the frequency boundaries
marked on the audiogram by more than + or - 3 seconds.
(E) It must be possible at each test frequency to place a horizontal line segment
parallel to the time axis on the audiogram, such that the audiometric tracing crosses the
line segment at least six times at that test frequency. At each test frequency the
threshold shall be the average of the midpoints of the tracing excursions.
Appendix D - Audiometric Test Rooms
This Appendix is Mandatory
Rooms used for audiometric testing shall not have background sound pressure levels
exceeding those in Table D-1 when measured by equipment conforming at least to the Type 2
requirements of American National Standard Specification for Sound Level Meters, S1.4-1971
(R1976), and to the Class II requirements of American National Standard Specification for
Octave, Half-Octave, and Third-Octave Band Filter Sets, S1.11-1971 (R1976).
TABLE D-1 - MAXIMUM ALLOWABLE OCTAVE-BAND SOUND PRESSURE LEVELS
FOR AUDIOMETRIC TEST ROOMS
_______________________________________________________________
Octave-band center
frequency (Hz)............... 500 1000 2000 4000 8000
Sound pressure level (dB) ... 40 40 47 57 62
_______________________________________________________________
Appendix E - Acoustic Calibration of Audiometers
This Appendix is Mandatory
Audiometer calibration shall be checked acoustically, at least annually, according to
the procedures described in this appendix. The equipment necessary to perform these
measurements is a sound level meter, octave-band filter set, and a National Bureau of
Standards 9A coupler. In making these measurements, the accuracy of the calibrating
equipment shall be sufficient to determine that the audiometer is within the tolerances
permitted by American Standard Specification for Audiometers, S3.6-1969.
(1) "Sound Pressure Output Check"
A. Place the earphone coupler over the microphone of the sound level meter and place
the earphone on the coupler.
B. Set the audiometer's hearing threshold level (HTL) dial to 70 dB.
C. Measure the sound pressure level of the tones at each test frequency from 500 Hz
through 6000 Hz for each earphone.
D. At each frequency the readout on the sound level meter should correspond to the
levels in Table E-1 or Table E-2, as appropriate, for the type of earphone, in the column
entitled "sound level meter reading."
(2) "Linearity Check"
A. With the earphone in place, set the frequency to 1000 Hz and the HTL dial on the
audiometer to 70 dB.
B. Measure the sound levels in the coupler at each 10-dB decrement from 70 dB to 10 dB,
noting the sound level meter reading at each setting.
C. For each 10-dB decrement on the audiometer the sound level meter should indicate a
corresponding 10 dB decrease.
D. This measurement may be made electrically with a voltmeter connected to the earphone
terminals.
(3) "Tolerances"
When any of the measured sound levels deviate from the levels in Table E-1 or Table E-2
by + or - 3 dB at any test frequency between 500 and 3000 Hz, 4 dB at 4000 Hz, or 5 dB at
6000 Hz, an exhaustive calibration is advised. An exhaustive calibration is required if
the deviations are greater than 15 dB or greater at any test frequency.
TABLE E-1 - REFERENCE THRESHOLD LEVELS FOR TELEPHONICS -
TDH-39 EARPHONES
_____________________________________________________________
Reference
threshold Sound
level for level
Frequency, Hz TDH-39 meter
earphones, reading,
dB dB
_____________________________________________________________
500 .................................. 11.5 81.5
1000 ................................. 7 77
2000 ................................. 9 79
3000 ................................. 10 80
4000 ................................. 9.5 79.5
6000 ................................. 15.5 85.5
_____________________________________________________________
TABLE E-2 - REFERENCE THRESHOLD LEVELS FOR TELEPHONICS -
TDH-49 EARPHONES
_____________________________________________________________
Reference
threshold Sound
level for level
Frequency, Hz TDH-49 meter
earphones, reading,
dB dB
____________________________________________________________
500 .................................. 13.5 83.5
1000 ................................. 7.5 77.5
2000 ................................. 11 81.0
3000 ................................. 9.5 79.5
4000 ................................. 10.5 80.5
6000 ................................. 13.5 83.5
___________________________________________________________
Appendix F - Calculations and Application of Age Corrections
to Audiograms
This Appendix Is Non-Mandatory
In determining whether a standard threshold shift has occurred, allowance may be made
for the contribution of aging to the change in hearing level by adjusting the most recent
audiogram. If the employer chooses to adjust the audiogram, the employer shall follow the
procedure described below. This procedure and the age correction tables were developed by
the National Institute for Occupational Safety and Health in the criteria document
entitled "Criteria for a Recommended Standard . . . Occupational Exposure to
Noise," ((HSM)-11001).
For each audiometric test frequency;
(i) Determine from Tables F-1 or F-2 the age correction values for the employee by:
(A) Finding the age at which the most recent audiogram was taken and recording the
corresponding values of age corrections at 1000 Hz through 6000 Hz;
(B) Finding the age at which the baseline audiogram was taken and recording the
corresponding values of age corrections at 1000 Hz through 6000 Hz.
(ii) Subtract the values found in step (i)(B) from the value found in step (i)(A).
(iii) The differences calculated in step (ii) represented that portion of the change in
hearing that may be due to aging.
EXAMPLE: Employee is a 32-year-old male. The audiometric history for his right ear is
shown in decibels below.
_____________________________________________________________
Audiometric test frequency (Hz)
Employee's age ___________________________________
1000 2000 3000 4000 6000
_____________________________________________________________
26....................... 10 5 5 10 5
*27...................... 0 0 0 5 5
28....................... 0 0 0 10 5
29....................... 5 0 5 15 5
30....................... 0 5 10 20 10
31....................... 5 10 20 15 15
*32...................... 5 10 10 25 20
_____________________________________________________________
The audiogram at age 27 is considered the baseline since it shows the best hearing
threshold levels. Asterisks have been used to identify the baseline and most recent
audiogram. A threshold shift of 20 dB exists at 4000 Hz between the audiograms taken at
ages 27 and 32.
(The threshold shift is computed by subtracting the hearing threshold at age 27, which
was 5, from the hearing threshold at age 32, which is 25). A retest audiogram has
confirmed this shift. The contribution of aging to this change in hearing may be estimated
in the following manner:
Go to Table F-1 and find the age correction values (in dB) for 4000 Hz at age 27 and
age 32.
____________________________________________________________
Frequency (Hz)
________________________________
1000 2000 3000 4000 6000
____________________________________________________________
Age 32................... 6 5 7 10 14
Age 27................... 5 4 6 7 11
___________________________________
Difference 1 1 1 3 3
____________________________________________________________
The difference represents the amount of hearing loss that may be attributed to aging in
the time period between the baseline audiogram and the most recent audiogram. In this
example, the difference at 4000 Hz is 3 dB. This value is subtracted from the hearing
level at 4000 Hz, which in the most recent audiogram is 25, yielding 22 after adjustment.
Then the hearing threshold in the baseline audiogram at 4000 Hz (5) is subtracted from the
adjusted annual audiogram hearing threshold at 4000 Hz (22). Thus the age-corrected
threshold shift would be 17 dB (as opposed to a threshold shift of 20 dB without age
correction).
TABLE F-1 - AGE CORRECTION VALUES IN DECIBELS FOR MALES
____________________________________________________________
Audiometric Test Frequency (Hz)
Years _________________________________
1000 2000 3000 4000 6000
____________________________________________________________
20 or younger........... 5 3 4 5 8
21 ..................... 5 3 4 5 8
22 ..................... 5 3 4 5 8
23 ..................... 5 3 4 6 9
24 ..................... 5 3 5 6 9
25 ..................... 5 3 5 7 10
26 ..................... 5 4 5 7 10
27 ..................... 5 4 6 7 11
28 ..................... 6 4 6 8 11
29 ..................... 6 4 6 8 12
30 ..................... 6 4 6 9 12
31 ..................... 6 4 7 9 13
32 ..................... 6 5 7 10 14
33 ..................... 6 5 7 10 14
34 ..................... 6 5 8 11 15
35 ..................... 7 5 8 11 15
36 ..................... 7 5 9 12 16
37 ..................... 7 6 9 12 17
38 ..................... 7 6 9 13 17
39 ..................... 7 6 10 14 18
40 ..................... 7 6 10 14 19
41 ..................... 7 6 10 14 20
42 ..................... 8 7 11 16 20
43 ..................... 8 7 12 16 21
44 ..................... 8 7 12 17 22
45 ..................... 8 7 13 18 23
46 ..................... 8 8 13 19 24
47 ..................... 8 8 14 19 24
48 ..................... 9 8 14 20 25
49 ..................... 9 9 15 21 26
50 ..................... 9 9 16 22 27
51 ..................... 9 9 16 23 28
52 ..................... 9 10 17 24 29
53 ..................... 9 10 18 25 30
54 ..................... 10 10 18 26 31
55 ..................... 10 11 19 27 32
56 ..................... 10 11 20 28 34
57 ..................... 10 11 21 29 35
58 ..................... 10 12 22 31 36
59 ..................... 11 12 22 32 37
60 or older ............ 11 13 23 33 38
___________________________________________________________
TABLE F-2 - AGE CORRECTION VALUES IN DECIBELS FOR FEMALES
____________________________________________________________
Audiometric Test Frequency (Hz)
Years _________________________________
1000 2000 3000 4000 6000
____________________________________________________________
20 or younger........... 7 4 3 3 6
21 ..................... 7 4 4 3 6
22 ..................... 7 4 4 4 6
23 ..................... 7 5 4 4 7
24 ..................... 7 5 4 4 7
25 ..................... 8 5 4 4 7
26 ..................... 8 5 5 4 8
27 ..................... 8 5 5 5 8
28 ..................... 8 5 5 5 8
29 ..................... 8 5 5 5 9
30 ..................... 8 6 5 5 9
31 ..................... 8 6 6 5 9
32 ..................... 9 6 6 6 10
33 ..................... 9 6 6 6 10
34 ..................... 9 6 6 6 10
35 ..................... 9 6 7 7 11
36 ..................... 9 7 7 7 11
37 ..................... 9 7 7 7 12
38 ..................... 10 7 7 7 12
39 ..................... 10 7 8 8 12
40 ..................... 10 7 8 8 13
41 ..................... 10 8 8 8 13
42 ..................... 10 8 9 9 13
43 ..................... 11 8 9 9 14
44 ..................... 11 8 9 9 14
45 ..................... 11 8 10 10 15
46 ..................... 11 9 10 10 15
47 ..................... 11 9 10 11 16
48 ..................... 12 9 11 11 16
49 ..................... 12 9 11 11 16
50 ..................... 12 10 11 12 17
51 ..................... 12 10 12 12 17
52 ..................... 12 10 12 13 18
53 ..................... 13 10 13 13 18
54 ..................... 13 11 13 14 19
55 ..................... 13 11 14 14 19
56 ..................... 13 11 14 15 20
57 ..................... 13 11 15 15 20
58 ..................... 14 12 15 16 21
59 ..................... 14 12 16 16 21
60 or older ............ 14 12 16 17 22
____________________________________________________________
Appendix G - Monitoring Noise Levels Non-Mandatory
Informational Appendix
This appendix provides information to help employers comply with the noise monitoring
obligations that are part of the hearing conservation amendment.
WHAT IS THE PURPOSE OF NOISE MONITORING?
This revised amendment requires that employees be placed in a hearing conservation
program if they are exposed to average noise levels of 85 dB or greater during an 8 hour
workday. In order to determine if exposures are at or above this level, it may be
necessary to measure or monitor the actual noise levels in the workplace and to estimate
the noise exposure or "dose" received by employees during the workday.
WHEN IS IT NECESSARY TO IMPLEMENT A NOISE MONITORING PROGRAM?
It is not necessary for every employer to measure workplace noise. Noise monitoring or
measuring must be conducted only when exposures are at or above 85 dB. Factors which
suggest that noise exposures in the workplace may be at this level include employee
complaints about the loudness of noise, indications that employees are losing their
hearing, or noisy conditions which make normal conversation difficult. The employer should
also consider any information available regarding noise emitted from specific machines. In
addition, actual workplace noise measurements can suggest whether or not a monitoring
program should be initiated.
HOW IS NOISE MEASURED?
Basically, there are two different instruments to measure noise exposures: the sound
level meter and the dosimeter. A sound level meter is a device that measures the intensity
of sound at a given moment. Since sound level meters provide a measure of sound intensity
at only one point in time, it is generally necessary to take a number of measurements at
different times during the day to estimate noise exposure over a workday. If noise levels
fluctuate, the amount of time noise remains at each of the various measured levels must be
determined.
To estimate employee noise exposures with a sound level meter it is also generally
necessary to take several measurements at different locations within the workplace. After
appropriate sound level meter readings are obtained, people sometimes draw
"maps" of the sound levels within different areas of the workplace. By using a
sound level "map" and information on employee locations throughout the day,
estimates of individual exposure levels can be developed. This measurement method is
generally referred to as "area" noise monitoring.
A dosimeter is like a sound level meter except that it stores sound level measurements
and integrates these measurements over time, providing an average noise exposure reading
for a given period of time, such as an 8-hour workday. With a dosimeter, a microphone is
attached to the employee's clothing and the exposure measurement is simply read at the end
of the desired time period. A reader may be used to read-out the dosimeter's measurements.
Since the dosimeter is worn by the employee, it measures noise levels in those locations
in which the employee travels. A sound level meter can also be positioned within the
immediate vicinity of the exposed worker to obtain an individual exposure estimate. Such
procedures are generally referred to as "personal" noise monitoring.
Area monitoring can be used to estimate noise exposure when the noise levels are
relatively constant and employees are not mobile. In workplaces where employees move about
in different areas or where the noise intensity tends to fluctuate over time, noise
exposure is generally more accurately estimated by the personal monitoring approach.
In situations where personal monitoring is appropriate, proper positioning of the
microphone is necessary to obtain accurate measurements. With a dosimeter, the microphone
is generally located on the shoulder and remains in that position for the entire workday.
With a sound level meter, the microphone is stationed near the employee's head, and the
instrument is usually held by an individual who follows the employee as he or she moves
about.
Manufacturer's instructions, contained in dosimeter and sound level meter operating
manuals, should be followed for calibration and maintenance. To ensure accurate results,
it is considered good professional practice to calibrate instruments before and after each
use.
HOW OFTEN IS IT NECESSARY TO MONITOR NOISE LEVELS?
The amendment requires that when there are significant changes in machinery or
production processes that may result in increased noise levels, remonitoring must be
conducted to determine whether additional employees need to be included in the hearing
conservation program. Many companies choose to remonitor periodically (once every year or
two) to ensure that all exposed employees are included in their hearing conservation
programs.
WHERE CAN EQUIPMENT AND TECHNICAL ADVICE BE OBTAINED?
Noise monitoring equipment may be either purchased or rented. Sound level meters cost
about $500 to $1,000, while dosimeters range in price from about $750 to $1,500. Smaller
companies may find it more economical to rent equipment rather than to purchase it. Names
of equipment suppliers may be found in the telephone book (Yellow Pages) under headings
such as: "Safety Equipment," "Industrial Hygiene," or
"Engineers-Acoustical." In addition to providing information on obtaining noise
monitoring equipment, many companies and individuals included under such listings can
provide professional advice on how to conduct a valid noise monitoring program. Some
audiological testing firms and industrial hygiene firms also provide noise monitoring
services. Universities with audiology, industrial hygiene, or acoustical engineering
departments may also provide information or may be able to help employers meet their
obligations under this amendment.
Free, on-site assistance may be obtained from OSHA-supported state and private
consultation organizations. These safety and health consultative entities generally give
priority to the needs of small businesses.
[61 FR 9227, March 7, 1996]
Appendix H - Availability of Referenced Documents
Paragraphs (c) through (o) of 29 CFR 1910.95 and the accompanying appendices contain
provisions which incorporate publications by reference. Generally, the publications
provide criteria for instruments to be used in monitoring and audiometric testing. These
criteria are intended to be mandatory when so indicated in the applicable paragraphs of
1910.95 and appendices.
It should be noted that OSHA does not require that employers purchase a copy of the
referenced publications. Employers, however, may desire to obtain a copy of the referenced
publications for their own information.
The designation of the paragraph of the standard in which the referenced publications
appear, the titles of the publications, and the availability of the publications are as
follows:
____________________________________________________________________
Paragraph Referenced Available
designation publication from --
____________________________________________________________________
Appendix B ..... "List of Personal Hearing National Technical
Protectors and Information
Attenuation Data," Service,
HEW Pub. No. 76-120, Port Royal Road,
1975. NTIS-PB267461. Springfield, VA
22161.
Appendix D ..... "Specification for Sound American National
Level Meters," Standards
S1.4-1971 (R1976). Institute, Inc.,
1430 Broadway,
New York, NY
10018.
1910.95(k)(2),
Appendix E ... "Specifications for American National
Audiometers," Standards
S3.6-1969. Institute, Inc.,
1430 Broadway,
New York, NY
10018.
Appendix D ..... "Specification for Octave, Back Numbers
Half-Octave and Department,
Third-Octave Band Dept. STD,
Filter Sets," American
S1.11-1971 (R1976). Institute of
Physics,
333 E. 45th St.,
New York, NY
10017;
American National
Standards
Institute, Inc.,
1430 Broadway,
New York, NY
10018.
____________________________________________________________________
The referenced publications (or a microfiche of the publications) are available for
review at many universities and public libraries throughout the country. These
publications may also be examined at the OSHA Technical Data Center, Room N2439, United
States Department of Labor, 200 Constitution Avenue, NW., Washington, DC 20210, (202)
219-7500 or at any OSHA Regional Office (see telephone directories under United States
Government - Labor Department).
[61 FR 9227, March 7, 1996]
Appendix I - Definitions
These definitions apply to the following terms as used in paragraphs (c) through (n) of
29 CFR 1910.95.
Action level - An 8-hour time-weighted average of 85 decibels
measured on the A-scale, slow response, or equivalently, a dose of
fifty percent.
Audiogram - A chart, graph, or table resulting from an audiometric
test showing an individual's hearing threshold levels as a
function of frequency.
Audiologist - A professional, specializing in the study and
rehabilitation of hearing, who is certified by the American
Speech-Language-Hearing Association or licensed by a state board
of examiners.
Baseline audiogram - The audiogram against which future audiograms
are compared.
Criterion sound level - A sound level of 90 decibels.
Decibel (dB) - Unit of measurement of sound level.
Hertz (Hz) - Unit of measurement of frequency, numerically equal to
cycles per second.
Medical pathology - A disorder or disease. For purposes of this
regulation, a condition or disease affecting the ear, which should
be treated by a physician specialist.
Noise dose - The ratio, expressed as a percentage, of (1) the time
integral, over a stated time or event, of the 0.6 power of the
measured SLOW exponential time-averaged, squared A-weighted sound
pressure and (2) the product of the criterion duration (8 hours)
and the 0.6 power of the squared sound pressure corresponding to
the criterion sound level (90 dB).
Noise dosimeter - An instrument that integrates a function of sound
pressure over a period of time in such a manner that it directly
indicates a noise dose.
Otolaryngologist - A physician specializing in diagnosis and
treatment of disorders of the ear, nose and throat.
Representative exposure - Measurements of an employee's noise dose
or 8-hour time-weighted average sound level that the employers
deem to be representative of the exposures of other employees in
the workplace.
Sound level - Ten times the common logarithm of the ratio of the
square of the measured A-weighted sound pressure to the square of
the standard reference pressure of 20 micropascals. Unit: decibels
(dB). For use with this regulation, SLOW time response, in
accordance with ANSI S1.4-1971 (R1976), is required.
Sound level meter - An instrument for the measurement of sound
level.
Time-weighted average sound level - That sound level, which if
constant over an 8-hour exposure, would result in the same noise
dose as is measured.
[39 FR 23502, June 27, 1974, as amended at 46 FR 4161, Jan. 16, 1981; 46 FR 62845, Dec.
29, 1981; 48 FR 9776, Mar. 8, 1983; 48 FR 29687, June 28, 1983; 54 FR 24333, June 7, 1989;
61 FR 5507, Feb. 13, 1996; 61 FR 9227, March 7, 1996]