Psychophysics: Decibels

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  • #1
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Main Question or Discussion Point

Decibels are the measuring unit for sound energy. The absolute threshold for hearing is arbitrarily defined as zero decibels. Every 10 decibels correspond to a ten-fold increase in sound. Thus, normal conversation (60 dB) is 10,000 time louder than a 20 dB whisper.
I don't understand the math of the 10 fold system.
Could someone go into detail of it for me?

I just don't see how that works.

10 db = 100
20 = 1000
30 = 10000?

i don't understand the system here.
 

Answers and Replies

  • #2
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It's a log scale

[tex]
I(db) = 10*log_{10}(\frac{I}{I_0})
[/tex]

For example

[tex]
10db = 10*log_{10}(10)
[/tex]

[tex]
30db = 10*log_{10}(1000)
[/tex]


[tex]
60db = 10*log_{10}(1000000)
[/tex]
 
  • #3
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I don't understand that log stuff or I think I'd have this understood by now.

==update==
Ah, I understand it a bit better now after doing some math work. Thank you.

simply the 6 part of 60 could signify 6 zeros after the 1, making it 1 million.
 
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