Question

Two identical sound `S_1` and `S_2` reach at a point P is phase. The resultant loudness at point P is `n` dB higher than the loudness of `S_1` the value of n is :
A. ` 2`
B. `4`
C. `5`
D. `6`

Answer 1

Correct Answer - D
Let `a` be the amplitude due to `S_(1) and S_(2)` individually .
Intensity due to `S_(1) = I_(1) = Ka^(2) `
Intensity due to ` S_(1) + S_(2) = I = K( 2a)^(2)`
`= 4 I_(1)`
`:. N = 10 log_(10) ((4 l_(1))/(I_(1)))`
` = 10 log _(10) (4) = 6`