Lo 1 (corrected)
-
Upload
arbinddhaliwal -
Category
Science
-
view
23 -
download
2
Transcript of Lo 1 (corrected)
![Page 1: Lo 1 (corrected)](https://reader035.fdocuments.us/reader035/viewer/2022062320/55c5d1ccbb61ebb6108b45c9/html5/thumbnails/1.jpg)
Measuring Sound
![Page 2: Lo 1 (corrected)](https://reader035.fdocuments.us/reader035/viewer/2022062320/55c5d1ccbb61ebb6108b45c9/html5/thumbnails/2.jpg)
Introduction
Everyone is familiar with sound, we have ears to detect it after all!
But what is sound? Sound is a mechanical wave which is
created by a vibrating object. But how do we measure it?
![Page 3: Lo 1 (corrected)](https://reader035.fdocuments.us/reader035/viewer/2022062320/55c5d1ccbb61ebb6108b45c9/html5/thumbnails/3.jpg)
Instrument
Sound Level Meter
![Page 4: Lo 1 (corrected)](https://reader035.fdocuments.us/reader035/viewer/2022062320/55c5d1ccbb61ebb6108b45c9/html5/thumbnails/4.jpg)
Common Sound Intensity Levels
http://windchimes.co.za/photos/sound_intensity_levels.gif
![Page 5: Lo 1 (corrected)](https://reader035.fdocuments.us/reader035/viewer/2022062320/55c5d1ccbb61ebb6108b45c9/html5/thumbnails/5.jpg)
Unit of measuring sound
Unit: Decibel (dB) Reference sound intensity level of 0
dB is an intensity of: I0=10-12 W/m2 (the quietest sound a human ear can detect)
All other sound intensities are measured in reference to this threshold hearing intensity.
![Page 6: Lo 1 (corrected)](https://reader035.fdocuments.us/reader035/viewer/2022062320/55c5d1ccbb61ebb6108b45c9/html5/thumbnails/6.jpg)
Sound Intensity Level
When comparing a specific sound intensity to the reference intensity (Io), it’s known as sound intensity level.
Equation:
Where B= “bel” I= specific sound intensity I0 reference intensity (I0=10-12 W/m2 )
![Page 7: Lo 1 (corrected)](https://reader035.fdocuments.us/reader035/viewer/2022062320/55c5d1ccbb61ebb6108b45c9/html5/thumbnails/7.jpg)
Question #1 :
A) You are at the Mariners soccer game where you are told the sound intensity is 10^-20
W/m2. What is the sound intensity level?
b) Is this level lower or higher than the threshold of human hearing?
*Hint*: What are you trying to find?*
![Page 8: Lo 1 (corrected)](https://reader035.fdocuments.us/reader035/viewer/2022062320/55c5d1ccbb61ebb6108b45c9/html5/thumbnails/8.jpg)
Solution #1:
A) Since you know sound intensity level corresponds to “B”, you would use the equation below and simply plug in the values you know.
I= specific sound intensity= 10^-20 W/m2
I0= reference intensity= 10^-12 W/m2
B= what you are trying to find. Calculate! Answer: -80 dB b) Since the answer is negative it’s indicating that the sound is below the threshold level for human hearing (because the threhold for human hearing is 0 dB).
![Page 9: Lo 1 (corrected)](https://reader035.fdocuments.us/reader035/viewer/2022062320/55c5d1ccbb61ebb6108b45c9/html5/thumbnails/9.jpg)
Question #2
You are at the Thunderbird Stadium watching a basketball game, where you find out the sound intensity level is 100 dB. What is the sound intensity in W/m2?
![Page 10: Lo 1 (corrected)](https://reader035.fdocuments.us/reader035/viewer/2022062320/55c5d1ccbb61ebb6108b45c9/html5/thumbnails/10.jpg)
Solution #2
You will need to rearrange the sound intensity level equation, to find sound intensity (I) inside the Thunderbird stadium.
![Page 11: Lo 1 (corrected)](https://reader035.fdocuments.us/reader035/viewer/2022062320/55c5d1ccbb61ebb6108b45c9/html5/thumbnails/11.jpg)
Solution continued...
Plug in known values:
Divide by 10:
![Page 12: Lo 1 (corrected)](https://reader035.fdocuments.us/reader035/viewer/2022062320/55c5d1ccbb61ebb6108b45c9/html5/thumbnails/12.jpg)
Solution continued…
Since it’s log base 10, everything can be written in base 10:
Isolate for I0=
Final Answer: 10-22 W/m2
*To check*: Just plug back into original equation
![Page 13: Lo 1 (corrected)](https://reader035.fdocuments.us/reader035/viewer/2022062320/55c5d1ccbb61ebb6108b45c9/html5/thumbnails/13.jpg)
Thank You!