How Loud Are Seven Clarinets Compared to One?

[wadesweatt]

Homework Statement

if one clarinet is playing a note at a sound level of 60 dB, what is the sound intensity of 7 clarinets playing identically at one time?

Homework Equations

is B=(10dB)log(I/Io) relevant to this?

The Attempt at a Solution

I just need to be pointed in the right direction, but its going to take some pretty obvious hints because I'm brand new to physics.

Thanks ahead of time.

Wade

 

[rl.bhat]

In place of I put 7I write another equation. Compare two equation to find the new intensity level.

 

[wadesweatt]

so I should put this:

B=(10dB)log(I/Io)

B=(10dB)log(7I/Io)

so is it 60=(10dB)log(7I/1)??

 

[rl.bhat]

so I should put this:

B=(10dB)log(I/Io)

B=(10dB)log(7I/Io)

so is it 60=(10dB)log(7I/1)??

No.
60=(10dB)log(I/Io)...(1)
B=(10dB)log(7I/Io)...(2)
From equations 1 and 2 find B

 

[wadesweatt]

I'm a little confused about how to do it? baby steps please?

 

[rl.bhat]

OK.
You can the eq. 2 as
B = 10dBlog(I/Io) + 10dBlog7
Now solve for B
Or
From equation find I using Io value. Then find intensity level for 7I

 

[wadesweatt]

what is the Io value? is that some standard value that I am missing?

Maybe that's why this is so difficult...it seems like there are too many variables...

 

[wadesweatt]

B = 10dBlog(I/Io) + 10dBlog7
Now solve for B

Would you explain how to solve for B when you don't know the value for I or Io? Also, the question asks for the intensity...so why am I solving for B? and also, isn't B 60?

 

[rl.bhat]

Find the definition of dB.

 

[rl.bhat]

Would you explain how to solve for B when you don't know the value for I or Io? Also, the question asks for the intensity...so why am I solving for B? and also, isn't B 60?

Then you can do this way.

From equation find I using Io value. Then find intensity of seven clarinets

 

[wadesweatt]

Then you can do this way.

From equation find I using Io value. Then find intensity of seven clarinets

You basically said this already. Is there anything else you can tell me? I looked up the definition for dB and it is basically the equation I have given to begin with. Still not sure how to get Io, or where to put the 60 in order to find the intensity like the problem asks. Please be clear, some of your answers have had typos and it makes it pretty hard to understand.

thanks again.

 

[rl.bhat]

B=(10dB)log(I/Io)
In the given problem B = 60 dB.
According to definition of intensity level Io is equal to 10^-12 W/m^2, threshold of human hearing. Here logarithm is taken to base 10.