Originally Posted by

**astuart** Hello,

Not sure if this is in the right forum - feel free to move it.

I have a question from my textbook that is throwing me off a bit.

The relative loudness of a sound D of intensity I is measured in decibels (db) where

$\displaystyle D = 10 log I/Io$

and Io is the standard threshold of audibility.

A) Express the intensity of I of a 30-db sound (the sound level of normal conversation) in terms of Io.

I think I'm supposed to form an equation for I in relation to Io, but I'm not sure what I'm supposed to do. Apparently the answer is "10^3(Io)".

I'm thinking it's something to do with the fact that I = 30, and the fact that there's a 10 log expression - something to do with the 3 being a divisor of 30 (by 10). I'm just not sure how the 30 gets turned into the exponent of 10 (expressed as 3).

Any tips?