Title 49

PART 227 APPENDIX A


Appendix A to Part 227 - Noise Exposure Computation

49:4.1.1.1.21.4.15.1.42 : Appendix A

Appendix A to Part 227 - Noise Exposure Computation

This appendix is mandatory.

I. Computation of Employee Noise Exposure

A. Noise dose is computed using Table A-1 as follows:

1. When the sound level, L, is constant over the entire work day, 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 duration permitted corresponding to the measured sound level, L, as given in Table A-1.

2. When the work day 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 duration permitted for that level as given by Table A-1.

B. The eight-hour TWA in dB may be computed from the dose, in percent, by means of the formula: TWA = 16.61 log10 (D/100) + 90. For an eight-hour work day with the noise level constant over the entire day, the TWA is equal to the measured sound level.

C. Exposure to impulsive or impact noise should not exceed 140 dB peak sound pressure level.

D. Any time that an employee spends deadheading shall be included in the calculation of the noise dose.

E. A table relating dose and TWA is given in Section II of this Appendix.

Table A-1 1

A-weighted sound level, L
(decibel)		 Duration
permitted
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
140 0.078