teK-- wrote:Actually I just re-read my post and realised my error. I meant that the Hertz were almost TWICE as loud. (since 6dB is perceived as being twice as loud, and the Hertz were 5dB more efficient).
Tek

About Decibels (dB)
Prepared by Gregg Vanderheiden Ph.D.
Trace R&D Center University of Wisconsin-Madison
What is a Decibel (dB)?
A dB or Decibel is a logarithmic unit of measure of the ratio between two numbers.
dB and Power (20dB = 100x)
When talking about power, 3dB represents a ratio of two to one or a doubling of power.
* Thus, a gain of 10dB would represent a ratio of ten to one for power - so 10 dB be 10 times the power
* A 40dB power gain would be 10,000 times the power.
dB and Voltage gain (20dB = 10x)
When talking about voltage, 6dB represents a ratio of two to one or a doubling of voltage.
* 20dB would represent a ratio of ten to one for voltage - so 20 dB would be 10 times the voltage.
* A 40dB voltage gain would be 100 times the voltage.
dB SPL (Sound Pressure Level) (20dB = 10x)
The term “SPL” stands for sound pressure level. SPL measures are taken with respect to the minimum threshold for human hearing. A 20 dB difference in SPL represents a ratio of ten-to-one in sound pressure.
* Thus, a 40dB SPL would be a sound pressure level that is 100 times greater than the sound pressure level of the quietest sound that normal human hearing can detect.
Perception of Loudness (20dB = 4x)
Interestingly, our perception of loudness is not the same as sound pressure level.
Although the actual formulae
is somewhat complex, as a rough rule of thumb, an increase of 10db SPL is perceived to be approximately twice as loud. * Thus a 20 Db gain would seem to be about 4 times as loud.
* And a 40 Db gain would seem to be about 16 times as loud.
From
http://trace.wisc.edu/docs/2004-About-dB/Sensitivity is a dB SPL measurement.
The incorrect use of dB happens often.