The Down Range Forum

Member Section => NFA Items => Topic started by: Tyler Durden on December 31, 2011, 10:47:44 AM

Title: Decibels, logarithms, and human hearing
Post by: Tyler Durden on December 31, 2011, 10:47:44 AM

You can read up on decibels here:

http://en.wikipedia.org/wiki/Decibel

the first thing it says right off the bat is that decibels are logarithmic.

this is what a logarithm  looks like when it is plotted on a graph:
(http://www.regentsprep.org/Regents/math/algtrig/ATP8b/inversegraph.gif)

look at the red line there.  notice that it is not a straight line ....it's not a linear relationship.  so if something is  quoted as for example having a 10 decibel noise reduction and something else has a 20 decibel noise reduction, it does NOT mean that things are half as quiet with the 20 decibel noise reduction gadget...or that things are twice as loud with the 10 decibel noise reduction gadget.

and as I understand it, the way us humans hear, each 3 decibel level increase in sound is actually doubling the noise.

http://emusician.com/tutorials/emusic_decibels_demystified_part_2/
(http://emusician.com/tutorials/SQ1_0701_fig1.jpg)

Title: Re: Decibels, logarithms, and human hearing
Post by: Timothy on December 31, 2011, 11:02:46 AM

Thanks to the Univ. of Oz..

http://www.animations.physics.unsw.edu.au/jw/dB.htm