"dorothy.bradbury" wrote:

Human Sensitivity:
o 3dB is the difference in noise level a human can perceive
o 1dB is the difference perceivable under laboratory conditions
---- vis., for general purchase use the figure of 3dB applies

Human Perception:
o 10dB increase in noise level is Perceived as a doubling in noise level
o 10dB decrease in noise level is Perceived as a halving in noise level

This sounds correct, but you said in your earlier post:

"o A reduction of 10dB(A) is a 50% reduction in sound energy"

So you mixed up 'sound energy' with 'Percieved noise level' .

Strictly, as 3dB reduction corresponds to 50% reduction in sound energy,
it follows that 10dB corresponds to a residual factor of 0.5^(10/3) in
other words 90% reduction in sound energy.