Scott, that is absolutely incorrect. As I said before, it takes twice the power to increase the sound pressure level 3 dB. 3 dB does not represent on any scale "twice as loud". This misconception arises from terminology confusion. In voltage measurements, twice the voltage would result in a 6 dB increase. I assume, though, you are referring to acoustical SPL measurements, and when you refer to "loudness" you are referring to sound pressure level (SPL). Regardless, the decibel is always a power ratio. It is not a unit of measurement like an inch, watt, liter, or a gram. It is a logarithm of a non-dimensional ratio of two power-like quantities.
