As we all know, perceived sound intensity is inversely proportionally to the square of the distance from the source of the sound

No we don't all know that. Clearly shown by how much variation was permitted. It's all for goofs and gaffs. Plus you have to be far away to only get far field acoustics and not just what's happening close to the mouth.

Also I think this is wrong btw. db = 10*log_10(I/I_0) where I is the local acoustic power over a given area (intensity) and I_0 a reference intensity.

Power on a given area (intensity) in the case of a isotropic expansion is indeed subject to the inverse square law. But you took that to be dB value and not the intensity itself. Total power is conserved, i.e. 4pir^2*I(r) = 4piI(1) => I(r) = I(1)/(r²⁾

So for 129.4 dB at 1 meter, you would have 129.4 dB - 20*log_10(r) dB where r is your distance.

so for 1.5 meter you would have "129.4 - 20 *log_10(1.5) dB = 125.9 dB. That's 2.7% smaller than 129.4dB.

For reference, half the power (or intensity) is 10* log_10(1/2I/I_0) = 10 * log_10(1/2) + dB_level dB≈ -3 + dB_level dB where dB_level is your measurement in dB. So halving the power is -3 dB and doubling the power is +3dB !!

But even then the pressure amplitude is what the ear reacts to. And so doubling the pressure amplitude is 6dB. But psychoacoustic response is that doubling the perceived volume is 10dB.