The above information is incorrect! 3 db is twice the sound pressure, or twice the volume. It takes twice as many speakers or twice as many watts to go up 3 db! Because our ears are inefficent, it takes an increase of 10 db for us to perceive the increase in volume as twice as loud.
Roger
Nope, not incorrect:
"A simple chart will help to understand the relationship
of the terms we have introduced: dB Change
Voltage
Power
Loudness
3
1.4X
2X
1.23X
6
2.0
4.0
1.52
10
3.16
10
2
20
10
100
4
40
100
10,000
16
Looking at the chart, and starting at the left, we can
see than an increase of 3dB results in a voltage
increase 1.4 times the original, a doubling of power, and
yields only a subjective increase in loudness only 1.23
times the original. To get a doubling of loudness, it is
important to note that an increase of 10dB is necessary.
And to reproduce that volume through our loudspeakers, note
that we require ten times more power from the amplifier!"
Full article here http://www.gcaudio.com/resources/howtos/voltageloudness.html