Question

The Sound Pressure Level (SPL) measured in open space (free field), at a distance of 6 m from a noise source is 80 dB. At a distance of 60 m, the SPL is

• A. 60 dB
• B. 8 dB
• C. 80 dB
• D. 1.34 dB

Answer 1

The correct option is A 60 dB

$\text{Sound level (dB)}\propto \frac{1}{distance}$

$20log\left(A_v\right)=80$

$\therefore A_v={10}^4$

$\text{for 6 m distance sound level =}{10}^4$
$\therefore \text{for 60 m sound level =}\frac{{10}^4}{10}={10}^3$

$\text{Sound level in (dB) = 20 log}{10}^3\text{for 60 m = 60 dB}$