Exponent/Logarithm Problem Solving Help

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March 8th 2011, 09:58 PM
dondonlouie

Exponent/Logarithm Problem Solving Help

I have a couple of questions that i need help withh :
1. Suppose a radio is playing loudly at a sound level of 80 decibels. What decibel level would make the radio sound one-fourth as loud?

how are you suppose to start this question? you don't use the decibel scale do you?

2. Show that a sound with d decibels has intensity E0(10)^(d/10), where E0 is the intensity of a sound with 0 decibels.

I have no idea what that question is asking for. D:

thanks in advance (:
March 8th 2011, 10:21 PM
earboth

Quote:

Originally Posted by dondonlouie

I have a couple of questions that i need help withh :
1. Suppose a radio is playing loudly at a sound level of 80 decibels. What decibel level would make the radio sound one-fourth as loud?

how are you suppose to start this question? you don't use the decibel scale do you?

2. Show that a sound with d decibels has intensity E0(10)^(d/10), where E0 is the intensity of a sound with 0 decibels.

I have no idea what that question is asking for. D:

thanks in advance (:

1. $E_0$ denotes the socalled stimulus threshold.

2. Have a look here: Weber
March 8th 2011, 10:35 PM
dondonlouie

but how would you solve the questions? i don't know how to set up the formula
March 8th 2011, 10:58 PM
earboth

Quote:

Originally Posted by dondonlouie

but how would you solve the questions? i don't know how to set up the formula

1. The noise of 80 dB is described by: $E_0 \cdot 10^{\frac{80}{10}}$

2. The increased noise is described by: $E_0 \cdot 10^{\frac{d}{10}}$

3. The ratio of both sound levels is:

$\dfrac{E_0 \cdot 10^{\frac{d}{10}}}{E_0 \cdot 10^{\frac{80}{10}}}=\dfrac54$

(Remark: $\frac54$ is one fourth more than 1)

4. Solve for d.

5. I'll leave the 2nd question for you.
March 8th 2011, 11:01 PM
dondonlouie

thanks (: