Sound is a mechanical wave generated by vibrating objects, measured in decibels (dB) using a sound level meter. The reference sound intensity level of 0 dB corresponds to the quietest sound detectable by the human ear, set at 10^-12 w/m2. The document includes examples to calculate sound intensity levels, demonstrating how specific sound intensities relate to the reference intensity.

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?

3.  Sound Level Meter

4. http://windchimes.co.za/photos/sound_intensi
ty_levels.gif

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.  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?*

8.  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^-20W/m2
 I0= reference intensity= 10^-12W/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).

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.

11.  Plug in known values:
 Divide by 10:

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

13. 