The following formula represents the exposure duration in minutes such that noise at x dBA for T(x) minutes or longer becomes hazardous (NIOSH 1998, 1-2). I will refer to T(x) values as T-durations.
9
運算式 10: "T" left parenthesis, "x" , right parenthesis equals StartFraction, 480 Over 2 Superscript, StartNestedFraction, left parenthesis, "x" minus 85 , right parenthesis NestedOver 3 , EndNestedFraction , Baseline , EndFractionTx=4802x−853
10
We can compose the two functions to obtain the T-duration as a function of being x metres away from a source that is D decibels loud at 1 metre away.
11
運算式 12: "S" left parenthesis, "x" , right parenthesis equals "T" left parenthesis, "L" Subscript, "D" , Baseline left parenthesis, "x" , right parenthesis , right parenthesis 有圖檔。 要進行圖形閱讀，請按 Alt + T 鍵。Sx=TLDx
12
Here is another slider one can use to play with the number of metres and see specific values of the decibels and T-durations, respectively.
13
運算式 14: "a" equals 1a=1
11
100100
14
運算式 15: "L" Subscript, "D" , Baseline left parenthesis, "a" , right parenthesis equals 115LDa
equals=
115115
15
運算式 16: "S" left parenthesis, "a" , right parenthesis equals 0.4 6 8 7 5Sa
equals=
0.4 6 8 7 50.46875
16
運算式 17: "x" equals "a" equals 1 有圖檔。 要進行圖形閱讀，請按 Alt + T 鍵。x=a
