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OCR for page 141
D
OSHA Regulations
OSHA REGULATIONS (STANDARDS - 29 CFR)2
OCCUPATIONAL NOISE EXPOSURE. - 1910.95
(SELECTED PORTIONS)
(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 deter-
mined as follows (Figure G-9~:
140 -
130 -
m
-
~ 120-
, _
IL 11O-
m ~ DO -
90 -
80 - _
i\//
ll
~ 00 200
125
120
m
115
11O ~
o
105 ~
.=
~ 00 A,
95
uu
on
ll 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 11
500 1,000 2,O00 4,000 8,OOO
Band Center Frequency (Hz)
FIGURE G-9 - Equivalent A-Weighted Sound Level
2 www.osha-slc.gov/OshStd_data/1910_0095.html, accessed 916199.
141
OCR for page 142
142
APPENDIX D
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 high-
est 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 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.
TABLE G-16 - PERMISSIBLE NOISE EXPOSURES (1)
Duration per day, hours
Sound level dBA slow response
8
6
2
1
1
11/2
-12
1/4 or less
90
92
95
97
100
102
105
110
115
Footnote(l) 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(l)/T(l) + 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.
(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, al-
lowance 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."
Representative terms from entire chapter:
sound levels