I'm affraid not. From the begining, You are mixig things.
A 10 dB of accoustic power change gives effectively x2 volume change but also a little bit over 3x SPL change (noise level, we are talking about).
Please try to make the difference between accoustic power, SPL (nosie level) and loudness (volume).
From AH press release
Airbus Helicopters
we are talking about
which reduce exterior noise levels by 50 percent (3 dB)
and not 3 dB power reduction which is not the same.
I also made a mistake. It should be approx. 23% volume. The value of 50% volume change would be for 6 dB of noise reduction. Not enough sleep I presume
Arrakis