Referring to Figure 2 in Shaw, determine the approximate value of the A-weighted

Question

Referring to Figure 2 in Shaw, determine the approximate value of the A-weighted sound level produced by a tractor-trailer at 55 mph at the following distances: (a) 20 m, (b) 100 m, (c) 200 m, (d) 500 m, and (e) 1000 m. Referring to Figure 5 in Shaw, determine the approximate values for the population average (4 kHz) of the A-weighted noise exposure level (to the nearest 5 dB) that would result, over 40 years of exposure, in a permanent threshold shift of (a) 5 dB, (b) 15 dB, (c) 25 dB, (d) 35 dB, and (e) 45 dB. Briefly describe five examples of the effects of prolonged noise exposure on humans. Give two examples (for each) of how noise effects can be reduced (a) at the source, (b) long the path of transmission, and (c) the receiver.

Explanation / Answer

1. At 20 m, sound level= 90*2*10^(-5) = 1.8 *10^-(3) Pa

At 100 m, sound level= 70*2*10^(-5) = 1.4 *10^-(3) Pa

At 200 m, sound level= 65*2*10^(-5) = 1.3 *10^-(3) Pa

At 500 m, sound level= 50*2*10^(-5) = 1.0*10^-(3) Pa

At 1000 m, sound level= 45*2*10^(-5) = 0.9 *10^-(3) Pa

2. for 5 dB shift, nose exposure level for population average 4 kHz is 80 dB

for 15 dB shift, nose exposure level for population average 4 kHz is 90 dB

For 25 dB shift, nose exposure level for population average 4 kHz is 96 dB

For 35 dB shift, nose exposure level for population average 4 kHz is 102 dB

For 45 dB shift, nose exposure level for population average 4 kHz is 107 dB

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