Question

At your house, you hear the busy freeway (the dB level of a freeway is 80 dB from 1.00 m away) and measure the noise at a constant level of 45 dB.

A. What is the power output of traffic on the freeway?

B. How far away is your house from the freeway?

C. How far from the freeway would you need to be for the sound to measure at 20 dB?

D. Town Hall is planning to add panels along the freeway that would absorb 70% of the sound energy (reduction in the power). What is the expected decibel level of freeway sounds at your house after the panels are installed?

Answer 1

Io logio ( 12 ) 8 c 5) I @ US = I= 10thx 10" 80dB Ig -12 Io | อ 12 w/ m2 I 10-4 W/m2 10 To P = uar Gali? (184)= Yaxo let us suppose house is at a distance ta 47 (d?) 4.5 To 1075 W/m2 4 10 - d = 56.23m d2 B 4 P 48x10-4 - 10 = d2 und2 Iolog (24) こ - 10-75

20 = to log ( 24 ) P 1610 w/ m2 - I - und2 yaxio-4 1010 - und? d = 103 = 1km 3 P P =) 0.3p = 6.3X4AXIO-4 w Now de cerel= lolog ( 24 ) 0.3x10-4 = 74.77 dB level lolog -12 jo