When the distance is twice larger

I would like to tell about the effect of distance to sound pressure level; sound pressure level’s unit is dB. It depends on the fluid pressure, and distance.

Fluid pressure is inversely proportional to the distance (p ≈ 1/r )

When the distance becomes twice, the fluid pressure will be a half.

And the equation of sound pressure level is dB = 20 log (P/Pref).


P1 = P

r1 = r

r2 = 2r

Then, P2 = 0.5 P

dB1 = 20 log (P1/Pref)= 20 log (P/Pref)

dB2 = 20 log (P2/Pref). = 20 log (0.5P/Pref). = dB1 + 20 log 0.5 = dB1 – 6.

dB2 = dB1 – 6

It is similar to love, when 2 people are in Long distance relationship (LDR), and the distance is twice larger, The Love will be reduced in 6 values. What are 6 values? I dunno exactly, maybe 6 watt, or 6 meter, or 6 days. So, keep your love and be patient.


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