Question

In the afternoon, the decibel level of a busy freeway is 85 dB with 90 cars passing a given point every minute. Late at night, the traffic flow is only 8 cars per minute. What is the late-night decibel level?

Answer 1

Answer: 75.45db

Explanation:

Sound intensity changes on a logarithmal basis, this applies for frequency, power etc

I.e number of decibel change dB is;

db change = 10log(p2/p1)

Therefore for intensity change from 90cars/min to 8 cars/min

db change = 10log(8/90) = - 10.55db

Therefore late night decibel level becomes;

85 - 10.55 = 75.45db