## anonymous one year ago You hear sounds at the following decibel levels: 5 dB, 10 dB, 20 dB, and 40 dB. Which sound is 10 times higher than the lowest pressure humans can hear? A. 5 dB B. 10 dB C. 20 dB D. 40 dB **Not sure how to find this!! :( Thank you!!:)

1. Michele_Laino

we have to use this definition: $\Large N = 10{\log _{10}}\left( {\frac{{{P_1}}}{{{P_0}}}} \right)$ where N is the number of decibels, and P_0 is a reference pressure

2. anonymous

oh okay! how can we find what to plug in?

3. Michele_Laino

we have to know how much is the lowest pressure

4. anonymous

ohhh would the lowest pressure be the 5 dB?

5. anonymous

oh oops

6. anonymous

or wait, it is 5 dB? :/

7. Michele_Laino

no, sorry, we can answer to your problem without know how much is the lowest pressure. Since we can write the lowest pressure as our reference pressure, and we can set P_1 = 10*P_0

8. anonymous

ohh okay! :)

9. Michele_Laino

so we have: $\Large \begin{gathered} {P_1} = 10{P_0} \hfill \\ N = 10{\log _{10}}\left( {\frac{{10{P_0}}}{{{P_0}}}} \right) = ...? \hfill \\ \end{gathered}$

10. anonymous

10?

11. Michele_Laino

ok! 10 dB

12. anonymous

ohh so that is our solution? 10 dB? :O

13. Michele_Laino

yes!

14. anonymous

woo! thank you!!:D

15. Michele_Laino

thanks! :)