This tool calculates the sound pressure level (dB) at a certain distance.

A. SPL distance calculator

The decibel calculator determines the sound level achieved by knowing the distance and sound pressure level from a sound source.

Fill in the box of  SPL1 ,distance1, distance2 to find the sound level if the distance change from the sound source. Note!! for comma numbers, use a period and not a comma!

B. Formula explained

To simplify the complicated calculation, we used the following formula:

   ∆SPL = 20.log (d₁ / d₂)

with:

∆ SPL : The Sound pressure level at a defined distance

d₁ = distance at which the SPL is given

d₂ = distance at which you want to know the SPL

C. Example 

SPL1 = 90dB at a distance of 3 meter from the sound source,

How much is the SPL at a distance of 10 meter from the sound source?

  ∆SPL = 20.log (d₁ / d₂)

  ∆SPL = 20.log (3/ 10)

  ∆SPL = 20.log (0.3)

  ∆SPL = -10,45 dB

The reduction of sound intensity of a distance of 10 m from the loudspeaker is 10dB. This means that you reached a sound level of 80db on a distance of 10 meter from the loudspeaker.