I'm reading through an EIS that has a blast monitoring section where blasts are characterized by Peak Pressure Level (PPL) measured in linear decibels (dBL). I cannot find a good definition of this decibel scale, my understanding is that the dB SPL (re 20 μPa) scale is logarithmic whereas this is (based on the name) linear?

I'm trying to understand the best way to relate these two scales to each other, if it's possible, so I can assess how loud this noise is to wildlife at different distances. The information I have on wildlife hearing capabilities is in db SPL.

  • 1
    $\begingroup$ Hi @Megan Petra, could you please add a reference to the original document/s. As highlighted by WMXZ, without further details, a clear answer is tough to provide. $\endgroup$
    – Thejasvi
    Jul 13, 2022 at 5:51
  • 2
    $\begingroup$ could it be linear as in "no weighing factor" as opposed to dB (A)? $\endgroup$
    – lframond
    Jul 13, 2022 at 12:23

1 Answer 1


A decibel (dB) is a logarithmic scale as you correctly understand. Why someone adds a 'linear' attributes to it, is confusing. I never have come across such term.

IMHO, Without seeing the EIS, there are really three possible answers to it:

  • it is simply a typo (happens very often, especially in large multi-author documents)
  • they have no idea what they are saying (should happen some time)
  • they invented some new metrics, where they needed a catchy name for (should then be explained in appendix (this is very rare)

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