A powerpoint summary about measuring sound, specifically about sound intensity levels and it's unit, equation and manipulating the equation to calculate specific values in two separate questions.
2. 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?
5. 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.
6. 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 )
7. 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?
*Hint*:What are you trying to find?*
8. Since you know sound intensity level corresponds to “B”,
you would use the equation below and simply plug in the
values you know.
I= reference intensity= 10^-12 W/m2
I0= 10^-20 W/m2
B= what you are trying to find.
Calculate!
Answer: 80 dB
9. You are at theThunderbird Stadium watching
a basketball game, where you find out the
sound intensity level is 100 dB.What is the
sound intensity inW/m2?
10. You will need to rearrange the sound
intensity level equation, to find sound
intensity (I) inside theThunderbird stadium.
12. Since it’s log base 10, everything can be written in base 10:
Isolate for I0=
FinalAnswer: 10-22W/m2
*To check*: Just plug back into original equation