Occupational Exposure to Noise Standard 1910.95

Noise Standard 04-06.pdf

Occupational Noise Exposure (29 CFR 1910.95)

Occupational Exposure to Noise Standard 1910.95

OMB: 1218-0048

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Occupational Safety and Health Admin., Labor
§ 1910.95

§ 1910.95

TABLE G–16—PERMISSIBLE NOISE EXPOSURES 1

Occupational noise exposure.

(a) Protection against the effects of
noise exposure shall be provided when
the sound levels exceed those shown in
Table G–16 when measured on the A
scale of a standard sound level meter
at slow response. When noise levels are
determined by octave band analysis,
the equivalent A-weighted sound level
may be determined as follows:

Sound
level dBA
slow response

Duration per day, hours

8 ...........................................................................
6 ...........................................................................
4 ...........................................................................
3 ...........................................................................
2 ...........................................................................
11⁄2 .......................................................................
1 ...........................................................................
1⁄2 .........................................................................
1⁄4 or less .............................................................

90
92
95
97
100
102
105
110
115

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: C1/T1+C2/
T2Cn/Tn 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.

FIGURE G–9
Equivalent sound level contours. Octave
band sound pressure levels may be converted
to the equivalent A-weighted sound level by
plotting them on this graph and noting the
A-weighted sound level corresponding to the
point of highest penetration into the sound
level contours. This equivalent A-weighted
sound level, which may differ from the actual A-weighted sound level of the noise, is
used to determine exposure limits from
Table 1.G–16.

(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.
(2) If the variations in noise level involve maxima at intervals of 1 second
or less, it is to be considered continuous.

(c) Hearing conservation program. (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.
(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. (1) When information
indicates that any employee’s exposure
may equal or exceed an 8-hour timeweighted average of 85 decibels, the
employer shall develop and implement
a monitoring program.
(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.
(ii) Where circumstances such as high
worker mobility, significant variations

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EC27OC91.023

211

§ 1910.95

29 CFR Ch. XVII (7–1–06 Edition)

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.
(2)(i) All continuous, intermittent
and impulsive sound levels from 80
decibels to 130 decibels shall be integrated into the noise measurements.
(ii) Instruments used to measure employee noise exposure shall be calibrated to ensure measurement accuracy.
(3) Monitoring shall be repeated
whenever a change in production, process, equipment or controls increases
noise exposures to the extent that:
(i) Additional employees may be exposed at or above the action level; or
(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 timeweighted 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. (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.
(2) The program shall be provided at
no cost to employees.
(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.
(4) All audiograms obtained pursuant
to this section shall meet the requirements of appendix C: Audiometric Measuring Instruments.
(5) Baseline audiogram. (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.
(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.
(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.
(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.
(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.
(7) Evaluation of audiogram. (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)

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Occupational Safety and Health Admin., Labor
of this section has occurred. This comparison may be done by a technician.
(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.
(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:
(A) A copy of the requirements for
hearing conservation as set forth in
paragraphs (c) through (n) of this section;
(B) The baseline audiogram and most
recent audiogram of the employee to
be evaluated;
(C) Measurements of background
sound
pressure
levels
in
the
audiometric test room as required in
appendix D: Audiometric Test Rooms.
(D) Records of audiometer calibrations required by paragraph (h)(5) of
this section.
(8) Follow-up procedures. (i) If a comparison of the annual audiogram to the
baseline audiogram indicates a standard threshold shift as defined in paragraph (g)(10) of this section has occurred, the employee shall be informed
of this fact in writing, within 21 days of
the determination.
(ii) Unless a physician determines
that the standard threshold shift is not
work related or aggravated by occupational noise exposure, the employer
shall ensure that the following steps
are taken when a standard threshold
shift occurs:
(A) Employees not using hearing protectors shall be fitted with hearing protectors, trained in their use and care,
and required to use them.
(B) Employees already using hearing
protectors shall be refitted and retrained in the use of hearing protectors
and provided with hearing protectors
offering greater attenuation if necessary.
(C) The employee shall be referred for
a clinical audiological evaluation or an
otological examination, as appropriate,
if additional testing is necessary or if
the employer suspects that a medical

§ 1910.95

pathology of the ear is caused or aggravated by the wearing of hearing protectors.
(D) The employee is informed of the
need for an otological examination if a
medical pathology of the ear that is
unrelated to the use of hearing protectors is suspected.
(iii) If subsequent audiometric testing of an employee whose exposure to
noise is less than an 8-hour TWA of 90
decibels indicates that a standard
threshold shift is not persistent, the
employer:
(A) Shall inform the employee of the
new audiometric interpretation; and
(B) May discontinue the required use
of hearing protectors for that employee.
(9) Revised baseline. An annual audiogram may be substituted for the baseline audiogram when, in the judgment
of the audiologist, otolaryngologist or
physician who is evaluating the audiogram:
(i) The standard threshold shift revealed by the audiogram is persistent;
or
(ii) The hearing threshold shown in
the annual audiogram indicates significant improvement over the baseline
audiogram.
(10) Standard threshold shift. (i) As
used in this section, a standard threshold shift is a change in hearing threshold relative to the baseline audiogram
of an average of 10 dB or more at 2000,
3000, and 4000 Hz in either ear.
(ii) In determining whether a standard threshold shift has occurred, allowance may be made for the contribution
of aging (presbycusis) to the change in
hearing level by correcting the annual
audiogram according to the procedure
described in appendix F: Calculation
and Application of Age Correction to
Audiograms.
(h) Audiometric test requirements. (1)
Audiometric tests shall be pure tone,
air conduction, hearing threshold examinations, with test frequencies including as a minimum 500, 1000, 2000,
3000, 4000, and 6000 Hz. Tests at each
frequency shall be taken separately for
each ear.
(2) Audiometric tests shall be conducted with audiometers (including
microprocessor audiometers) that meet

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§ 1910.95

29 CFR Ch. XVII (7–1–06 Edition)

the specifications of, and are maintained and used in accordance with,
American National Standard Specification for Audiometers, S3.6–1969, which
is incorporated by reference as specified in § 1910.6.
(3) Pulsed-tone and self-recording
audiometers, if used, shall meet the requirements specified in appendix C:
Audiometric Measuring Instruments.
(4) Audiometric examinations shall
be administered in a room meeting the
requirements listed in appendix D:
Audiometric Test Rooms.
(5) Audiometer calibration. (i) The
functional operation of the audiometer
shall be checked before each day’s use
by testing a person with known, stable
hearing thresholds, and by listening to
the audiometer’s output to make sure
that the output is free from distorted
or unwanted sounds. Deviations of 10
decibels or greater require an acoustic
calibration.
(ii) Audiometer calibration shall be
checked acoustically at least annually
in accordance with appendix E: Acoustic
Calibration of Audiometers. Test frequencies below 500 Hz and above 6000 Hz
may be omitted from this check. Deviations of 15 decibels or greater require
an exhaustive calibration.
(iii) An exhaustive calibration shall
be performed at least every two years
in accordance with sections 4.1.2; 4.1.3.;
4.1.4.3; 4.2; 4.4.1; 4.4.2; 4.4.3; and 4.5 of
the American National Standard Specification for Audiometers, S3.6–1969.
Test frequencies below 500 Hz and
above 6000 Hz may be omitted from this
calibration.
(i) Hearing protectors. (1) Employers
shall make hearing protectors available to all employees exposed to an 8hour time-weighted average of 85 decibels or greater at no cost to the employees. Hearing protectors shall be replaced as necessary.
(2) Employers shall ensure that hearing protectors are worn:
(i) By an employee who is required by
paragraph (b)(1) of this section to wear
personal protective equipment; and
(ii) By any employee who is exposed
to an 8-hour time-weighted average of
85 decibels or greater, and who:
(A) Has not yet had a baseline audiogram established pursuant to paragraph (g)(5)(ii); or

(B) Has experienced a standard
threshold shift.
(3) Employees shall be given the opportunity to select their hearing protectors from a variety of suitable hearing protectors provided by the employer.
(4) The employer shall provide training in the use and care of all hearing
protectors provided to employees.
(5) The employer shall ensure proper
initial fitting and supervise the correct
use of all hearing protectors.
(j) Hearing protector attenuation. (1)
The employer shall evaluate hearing
protector attenuation for the specific
noise environments in which the protector will be used. The employer shall
use one of the evaluation methods described in appendix B: Methods for Estimating the Adequacy of Hearing Protection Attenuation.
(2) Hearing protectors must attenuate employee exposure at least to an 8hour time-weighted average of 90 decibels as required by paragraph (b) of
this section.
(3) For employees who have experienced a standard threshold shift, hearing protectors must attenuate employee exposure to an 8-hour timeweighted average of 85 decibels or
below.
(4) The adequacy of hearing protector
attenuation shall be re-evaluated
whenever employee noise exposures increase to the extent that the hearing
protectors provided may no longer provide adequate attenuation. The employer shall provide more effective
hearing protectors where necessary.
(k) Training program. (1) The employer shall institute a training program for all employees who are exposed to noise at or above an 8-hour
time-weighted average of 85 decibels,
and shall ensure employee participation in such program.
(2) The training program shall be repeated annually for each employee included in the hearing conservation program. Information provided in the
training program shall be updated to
be consistent with changes in protective equipment and work processes.
(3) The employer shall ensure that
each employee is informed of the following:
(i) The effects of noise on hearing;

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Occupational Safety and Health Admin., Labor
(ii) The purpose of hearing protectors, the advantages, disadvantages,
and attenuation of various types, and
instructions on selection, fitting, use,
and care; and
(iii) The purpose of audiometric testing, and an explanation of the test procedures.
(l) Access to information and training
materials. (1) The employer shall make
available to affected employees or
their representatives copies of this
standard and shall also post a copy in
the workplace.
(2) The employer shall provide to affected employees any informational
materials pertaining to the standard
that are supplied to the employer by
the Assistant Secretary.
(3) The employer shall provide, upon
request, all materials related to the
employer’s training and education program pertaining to this standard to the
Assistant Secretary and the Director.
(m) Recordkeeping—(1) Exposure measurements. The employer shall maintain
an accurate record of all employee exposure measurements required by paragraph (d) of this section.
(2) Audiometric tests. (i) The employer
shall retain all employee audiometric
test records obtained pursuant to paragraph (g) of this section:
(ii) This record shall include:
(A) Name and job classification of
the employee;
(B) Date of the audiogram;
(C) The examiner’s name;
(D) Date of the last acoustic or exhaustive calibration of the audiometer;
and
(E) Employee’s most recent noise exposure assessment.
(F) The employer shall maintain accurate records of the measurements of
the background sound pressure levels
in audiometric test rooms.
(3) Record retention. The employer
shall retain records required in this
paragraph (m) for at least the following
periods.
(i) Noise exposure measurement
records shall be retained for two years.
(ii) Audiometric test records shall be
retained for the duration of the affected employee’s employment.
(4) Access to records. All records required by this section shall be provided
upon request to employees, former em-

§ 1910.95

ployees, representatives designated by
the individual employee, and the Assistant Secretary. The provisions of 29
CFR 1910.1020 (a)–(e) and (g)–(i) apply to
access to records under this section.
(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. (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.
(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.
APPENDIX A TO § 1910.95—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(C1/T1+C2/T2+Cn/Tn),
where Cn indicates the total time of exposure
at a specific noise level, and Tn 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 log10 (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.

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§ 1910.95

29 CFR Ch. XVII (7–1–06 Edition)

(3) A table relating dose and TWA is given
in Section II.

TABLE G–16A
A-weighted sound level, L (decibel)

80 ...........................................................................
81 ...........................................................................
82 ...........................................................................
83 ...........................................................................
84 ...........................................................................
85 ...........................................................................
86 ...........................................................................
87 ...........................................................................
88 ...........................................................................
89 ...........................................................................
90 ...........................................................................
91 ...........................................................................
92 ...........................................................................
93 ...........................................................................
94 ...........................................................................
95 ...........................................................................
96 ...........................................................................
97 ...........................................................................
98 ...........................................................................
99 ...........................................................................
100 .........................................................................
101 .........................................................................
102 .........................................................................
103 .........................................................................
104 .........................................................................
105 .........................................................................
106 .........................................................................
107 .........................................................................
108 .........................................................................
109 .........................................................................
110 .........................................................................
111 .........................................................................
112 .........................................................................
113 .........................................................................
114 .........................................................................
115 .........................................................................
116 .........................................................................
117 .........................................................................
118 .........................................................................
119 .........................................................................
120 .........................................................................
121 .........................................................................
122 .........................................................................
123 .........................................................................
124 .........................................................................
125 .........................................................................
126 .........................................................................
127 .........................................................................
128 .........................................................................
129 .........................................................................
130 .........................................................................

Reference
duration,
T (hour)
32
27.9
24.3
21.1
18.4
16
13.9
12.1
10.6
9.2
8
7.0
6.1
5.3
4.6
4
3.5
3.0
2.6
2.3
2
1.7
1.5
1.3
1.1
1
0.87
0.76
0.66
0.57
0.5
0.44
0.38
0.33
0.29
0.25
0.22
0.19
0.16
0.14
0.125
0.11
0.095
0.082
0.072
0.063
0.054
0.047
0.041
0.036
0.031

In the above table the reference duration,
T, is computed by
8
T

2(L¥90)/5

where L is the measured A-weighted sound
level.

II. CONVERSION BETWEEN ‘‘DOSE’’ AND ‘‘8HOUR 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 log10 (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
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99

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TWA
73.4
76.3
78.4
80.0
81.3
82.4
83.4
84.2
85.0
85.7
86.3
86.9
87.4
87.9
88.4
88.5
88.6
88.7
88.7
88.8
88.9
89.0
89.1
89.2
89.2
89.3
89.4
89.5
89.6
89.6
89.7
89.8
89.9
89.9

Occupational Safety and Health Admin., Labor
TABLE A–1—CONVERSION FROM ‘‘PERCENT
NOISE EXPOSURE’’ OR ‘‘DOSE’’ TO ‘‘8-HOUR
TIME-WEIGHTED AVERAGE SOUND LEVEL’’
(TWA)—Continued
Dose or percent noise exposure
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
125
130
135
140
145
150
155
160
165
170
175
180
185
190
195
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340
350
360
370
380
390
400
410
420
430
440
450
460
470
480
490
500
510

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§ 1910.95

TABLE A–1—CONVERSION FROM ‘‘PERCENT
NOISE EXPOSURE’’ OR ‘‘DOSE’’ TO ‘‘8-HOUR
TIME-WEIGHTED AVERAGE SOUND LEVEL’’
(TWA)—Continued

TWA

Dose or percent noise exposure

90.0
90.1
90.1
90.2
90.3
90.4
90.4
90.5
90.6
90.6
90.7
90.8
90.8
90.9
90.9
91.1
91.1
91.1
91.2
91.3
91.3
91.6
91.9
92.2
92.4
92.7
92.9
93.2
93.4
93.6
93.8
94.0
94.2
94.4
94.6
94.8
95.0
95.4
95.7
96.0
96.3
96.6
96.9
97.2
97.4
97.7
97.9
98.2
98.4
98.6
98.8
99.0
99.2
99.4
99.6
99.8
100.0
100.2
100.4
100.5
100.7
100.8
101.0
101.2
101.3
101.5
101.6
101.8

520
530
540
550
560
570
580
590
600
610
620
630
640
650
660
670
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APPENDIX B TO § 1910.95—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).

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§ 1910.95

29 CFR Ch. XVII (7–1–06 Edition)

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
#1B1, #1B2 and #1B3. The NRR described
below is a simplification of NIOSH method
#1B2. The most complex method is NIOSH
method #1B1, 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 Aweighted TWA to obtain the estimated Aweighted 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 Cweighting 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 TO § 1910.95—AUDIOMETRIC
MEASURING INSTRUMENTS
This Appendix is Mandatory
1. In the event that pulsed-tone audiometers are used, they shall have a tone ontime 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 (± 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
± 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

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Occupational Safety and Health Admin., Labor
threshold shall be the average
midpoints of the tracing excursions.

the

APPENDIX D TO § 1910.95—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).

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 ± 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

TABLE D–1—MAXIMUM ALLOWABLE OCTAVEBAND SOUND PRESSURE LEVELS FOR
AUDIOMETRIC TEST ROOMS
Octave-band center frequency (Hz) ................
Sound pressure level
(dB) .............................

500

1000

2000

4000

8000

APPENDIX E TO § 1910.95—ACOUSTIC
CALIBRATION OF AUDIOMETERS

Frequency, Hz

Reference
threshold
level for
TDH–39
earphones,
dB

Sound
level meter
reading,
dB

11.5
7
9
10
9.5
15.5

81.5
77
79
80
79.5
85.5

500 .................................................
1000 ...............................................
2000 ...............................................
3000 ...............................................
4000 ...............................................
6000 ...............................................

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.

§ 1910.95

TABLE E–2—REFERENCE THRESHOLD LEVELS
FOR TELEPHONICS—TDH–49 EARPHONES

Frequency, Hz

500 .....................................................
1000 ...................................................
2000 ...................................................
3000 ...................................................
4000 ...................................................
6000 ...................................................

Reference
threshold
level for
TDH–49
earphones,
dB
13.5
7.5
11
9.5
10.5
13.5

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77.5
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80.5
83.5

APPENDIX F TO § 1910.95—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;

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§ 1910.95

29 CFR Ch. XVII (7–1–06 Edition)

(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
26 .........................
*27 ........................
28 .........................
29 .........................
30 .........................
31 .........................
*32 ........................

10
0
0
5
0
5
5

2000
5
0
0
0
5
10
10

3000

4000

5
0
0
5
10
20
10

10
5
10
15
20
15
25

6000
5
5
5
5
10
15
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.

(as opposed to a threshold shift of 20 dB
without age correction).

TABLE F–1—AGE CORRECTION VALUES IN
DECIBELS FOR MALES
Audiometric Test Frequencies (Hz)
Years
1000
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60

Frequency (Hz)
1000
Age 32 ..................
Age 27 ..................

6
5

2000
5
4

3000

4000

7
6

10
7

or younger .......
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
or older ............

5
5
5
5
5
5
5
5
6
6
6
6
6
6
6
7
7
7
7
7
7
7
8
8
8
8
8
8
9
9
9
9
9
9
10
10
10
10
10
11
11

3
3
3
3
3
3
4
4
4
4
4
4
5
5
5
5
5
6
6
6
6
6
7
7
7
7
8
8
8
9
9
9
10
10
10
11
11
11
12
12
13

3000
4
4
4
4
5
5
5
6
6
6
6
7
7
7
8
8
9
9
9
10
10
10
11
12
12
13
13
14
14
15
16
16
17
18
18
19
20
21
22
22
23

14
11

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8
8
9
9
10
10
11
11
12
12
13
14
14
15
15
16
17
17
18
19
20
20
21
22
23
24
24
25
26
27
28
29
30
31
32
34
35
36
37
38

Audiometric Test Frequencies (Hz)
Years
2000

3000

20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35

7
7
7
7
7
8
8
8
8
8
8
8
9
9
9
9

4
4
4
5
5
5
5
5
5
5
6
6
6
6
6
6

3
4
4
4
4
4
5
5
5
5
5
6
6
6
6
7

220

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6000

5
5
5
6
6
7
7
7
8
8
9
9
10
10
11
11
12
12
13
14
14
14
16
16
17
18
19
19
20
21
22
23
24
25
26
27
28
29
31
32
33

4000

6000

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

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4000

TABLE F–2—AGE CORRECTION VALUES IN
DECIBELS FOR FEMALES

6000

1000
Difference ......

2000

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3
3
4
4
4
4
4
5
5
5
5
5
6
6
6
7

6
6
6
7
7
7
8
8
8
9
9
9
10
10
10
11

Occupational Safety and Health Admin., Labor
TABLE F–2—AGE CORRECTION VALUES IN
DECIBELS FOR FEMALES—Continued
Audiometric Test Frequencies (Hz)
Years
1000
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60

9
9
10
10
10
10
10
11
11
11
11
11
12
12
12
12
12
13
13
13
13
13
14
14
14

2000
7
7
7
7
7
8
8
8
8
8
9
9
9
9
10
10
10
10
11
11
11
11
12
12
12

3000

4000

7
7
7
8
8
8
9
9
9
10
10
10
11
11
11
12
12
13
13
14
14
15
15
16
16

7
7
7
8
8
8
9
9
9
10
10
11
11
11
12
12
13
13
14
14
15
15
16
16
17

6000
11
12
12
12
13
13
13
14
14
15
15
16
16
16
17
17
18
18
19
19
20
20
21
21
22

APPENDIX G TO § 1910.95—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?

§ 1910.95

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

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§ 1910.95

29 CFR Ch. XVII (7–1–06 Edition)

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.
APPENDIX H TO § 1910.95—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 designation

Referenced publication

Available from—

Appendix B .........................

‘‘List of Personal Hearing Protectors and
Attenuation Data,’’ HEW Pub. No. 76–
120, 1975. NTIS-PB267461.
‘‘Specification for Sound Level Meters,’’
S1.4–1971 (R1976).
‘‘Specifications for Audiometers,’’ S3.6–
1969.
‘‘Specification for Octave, Half-Octave
and Third-Octave Band Filter Sets,’’
S1.11–1971 (R1976).

National Technical Information Service, Port Royal
Road, Springfield, VA 22161.

Appendix D .........................
§ 1910.95(k)(2), appendix E
Appendix D .........................

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).
APPENDIX I TO § 1910.95—DEFINITIONS
These definitions apply to the following
terms as used in paragraphs (c) through (n)
of 29 CFR 1910.95.

American National Standards Institute, Inc., 1430
Broadway, New York, NY 10018.
American National Standards Institute, Inc., 1430
Broadway, New York, NY 10018.
Back Numbers Department, Dept. STD, American Institute of Physics, 333 E. 45th St., New York, NY
10017; American National Standards Institute, Inc.,
1430 Broadway, New York, NY 10018.

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 SpeechLanguage-Hearing Association or licensed
by a state board of examiners.
Baseline audiogram—The audiogram against
which future audiograms are compared.

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Occupational Safety and Health Admin., Labor
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 timeweighted 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 8hour 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
9236, Mar. 7, 1996; 71 FR 16672, Apr. 3, 2006]

§ 1910.97

Nonionizing radiation.

(a) Electromagnetic radiation—(1) Definitions applicable to this paragraph. (i)
The term electromagnetic radiation is restricted to that portion of the spectrum commonly defined as the radio
frequency region, which for the purpose
of this specification shall include the
microwave frequency region.
(ii) Partial body irradiation. Pertains
to the case in which part of the body is

§ 1910.97

exposed to the incident electromagnetic energy.
(iii) Radiation protection guide. Radiation level which should not be exceeded without careful consideration of the
reasons for doing so.
(iv) The word ‘‘symbol’’ as used in
this specification refers to the overall
design, shape, and coloring of the rf radiation sign shown in figure G–11.
(v) Whole body irradiation. Pertains to
the case in which the entire body is exposed to the incident electromagnetic
energy or in which the cross section of
the body is smaller than the cross section of the incident radiation beam.
(2) Radiation protection guide. (i) For
normal environmental conditions and
for incident electromagnetic energy of
frequencies from 10 MHz to 100 GHz,
the radiation protection guide is 10
mW/cm.2 (milliwatt per square centimeter) as averaged over any possible
0.1-hour period. This means the following:
Power density: 10 mW./cm.2 for periods of 0.1hour or more.
Energy density: 1 mW.-hr./cm.2 (milliwatt
hour per square centimeter) during any 0.1hour period.

This guide applies whether the radiation is continuous or intermittent.
(ii) These formulated recommendations pertain to both whole body irradiation and partial body irradiation.
Partial body irradiation must be included since it has been shown that
some parts of the human body (e.g.,
eyes, testicles) may be harmed if exposed to incident radiation levels significantly in excess of the recommended levels.
(3) Warning symbol. (i) The warning
symbol for radio frequency radiation
hazards shall consist of a red isosceles
triangle above an inverted black isosceles triangle, separated and outlined
by an aluminum color border. The
words ‘‘Warning—Radio-Frequency Radiation Hazard’’ shall appear in the
upper triangle. See figure G–11.
(ii) American National Standard
Safety Color Code for Marking Physical Hazards and the Identification of
Certain Equipment, Z53.1–1953, which is
incorporated by reference as specified
in § 1910.6, shall be used for color specification. All lettering and the border
shall be of aluminum color.

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File Type	application/pdf
File Title	Document
Subject	Extracted Pages
Author	U.S. Government Printing Office
File Modified	2006-08-15
File Created	2006-08-15