Quote Originally Posted by Jonathan View Post
Half is surely -3dB as log(3)=0.48.
No its 6dB for half the sound pressure output. Consider it the otherway around and you get the idea ie. 3dB increase is only half rather than double.

Plus the frequency response of the human ear isn't flat, so if one operates at a higher speed that would make a difference...
Not only that but also with a higher mean sound pressure level there is some compression of this. The fletcher munson curve is the commonly accepted equal loudness curve used to describe the frequency response of the ear when considered as a transducer.