Question

At a distance of 20 m from a source of sound, the sound level is 40 dB. If the observer backs up to a distance of 40 m from the source, what will the sound level be? O A. 34 dB O B. 28 dB ° C. 20 dB O D. 10 dB

Answer 1

The sound level is 34 dB.

(A) is correct option.

Step-by-step explanation:

Given that,

Distance from a source of sound
`r_(1)=20 m`

Sound level
`L_(1)= 40\ dB`

Distance from a source of sound
`r_(2)=40\ m`

We need to calculate the sound level

Using equation

`L_(2)=L_(1)-|20 log((r_(1))/(r_(2)))|`

`L_(2)=40-|20 log((20)/(40))|`

`L_(2)=40-|20 log(0.5)|`

`L_(2)=33.9\ dB`

`L_(2)=34\ dB`

Hence, The sound level is 34 dB.