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331 4.1 Decibel
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Range of aduible sound
10^14
: 1
rocket going off
: wind in trees
to test hearing we transfer the audlibe sound ratio into
a point system
0 - 140
10^1
10^2
10^3
10
100
1000
100,000,000
x 1,000,000 =
10^8 x 10^6 = 10^14
8 + 6 = 14
log2 =
.30103
10^1.? = 80
80 = 2x2x2x10
= log2 x log2 x log2 x log10
10^.3 x 10^.3 x 10^.3 x 10^1
.3 + .3 + .3 + 1 = 1.9
10^1.9 = 80
Hertz
Hz
Decibell
dB
Alexander Graham Bell
teacher / scientist
1847 - 1922
works with deaf
work lead to telephone / aviation
Scottich immigrant to Canada
married a deaf women
bffs with Helen Keller
wanted to switch to the phonetic alphabet
forbid signing
thought the deaf and blind should not reproduce
decibel equation: dB spl
dB SPL = 20 log (Pm / Pr)
where:
Pr = 20 uPa
Blaise Pascal
French Scientist / Philoshopher
1623 - 1662
Physicist / Mathematician
Measurement of atmoshperic pressure
dB SPL tells you...
how far away from the reference you are
0 dB SPL means
this is NOT 0, it means that you are at the reference
Pm = 8,000 uPa
dBspl = ?
dBspl = 20 log(Pm/Pr) Pr = 20uPa
= 20 log (8000/20)
= 20 log (400) 400=2x2x100
= 20 (2.6) 400=10^.3 x 10^.3 x 10^2
dBspl = 52 400=10^2.6
Author
shanamd2010
ID
130645
Card Set
331 4.1 Decibel
Description
CDO 331
Updated
2012-01-30T17:41:14Z
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