Comparing Sounds: 80 dB, 30 dB, and 50 dB

[homevolend]

Homework Statement

How many times quiter or louder is a sound at
1. 80 dB
2. 30 dB
than a sound 50 dB

Homework Equations

dB2=dB1-dB2?

The Attempt at a Solution

Would this just mean

1. 30 dB louder
2. 2 dB softer?

Or how would I finds "times louder".
Sorry for bad english.

 

[berkeman]

Homework Statement

How many times quiter or louder is a sound at
1. 80 dB
2. 30 dB
than a sound 50 dB

Homework Equations

dB2=dB1-dB2?

The Attempt at a Solution

Would this just mean

1. 30 dB louder
2. 2 dB softer?

Or how would I finds "times louder".
Sorry for bad english.

dB or deciBells are a logarithmic way of expressing ratios:

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

For sound power (loudness), the equation is R = 10*log(P1/P2)

So if P1 is equal to P2, the ratio R is 0db.

If P1 is equal to 10 * P2, the ratio R is 10dB.

Makes sense?