Sound intensity is defined as the power of a sound source divided by the surface area over which the sound is spread. The formula for sound intensity is sound power divided by area. If sound spreads equally in all directions from a source, the intensity equals the power divided by the surface area of a sphere. Sound level is defined as the logarithm of the ratio of a measured sound intensity to a reference threshold intensity. The formula for sound level is 10 times the logarithm of the measured intensity divided by the threshold intensity.

8. › Definition : as energy sound that moved every unit of time
every unit of vast
› Formula :
with I = Sound Intensity
P = power of source sound (W)
A = vast

9. › If the sound spread to every direction, so that the sound
intensity equals with the power that moved divided of vast
countenance
› Formula :

10. Example…
The wave of sound spouted from a source with the power
3,6π mW. Fixed that the sound intensity…
– Known :
R = 3m
– Ask : I…
– Answer :

11. › Definition : logarithm equals of the sound intensity towards
threshold intensity
› Formula :
with TI = Intensity Level (dB)
I = sound intensity
= threshold intensity

12. Example…
The wave of sound spouted from a source with the power
3,6π mW. Fixed the intensity level on the distance 3m from the
source…
Known :
R = 3m
Ask : I…
Answer :