- #1
jangchen
- 12
- 3
- Homework Statement
- A loudspeaker, mounted on a tall pole, is engineered to emit 75% of its sound energy into the forward hemisphere, 25% toward the back. You measure an 85 dB sound intensity level when standing 3.5 m in front of and 2.5 m below the speaker. What is the speaker’s power output?
- Relevant Equations
- dB = 10 log(I / Io) , I = P / 4pi×r^2
I is proportionate to E.
r = 4.3xxm
So I put 0.75I
The answer is 49mW..
But I got 97.xxmW
What is wrong?
r = 4.3xxm
So I put 0.75I
The answer is 49mW..
But I got 97.xxmW
What is wrong?