Context: I'm trying to do formant estimation. My first attempt didn't work out all that well so I'm trying to follow closely Praat since their formant estimation is remarkably accurate.

Question: I thought it was obvious to apply the filter (pre-emphasis) before Downsampling, however Praat doesn't. Is there a reason for this? Are filters usually applied before or after downsampling?

  • 1
    $\begingroup$ what's Praat ? You should add some info. $\endgroup$
    – Ben
    Sep 30, 2020 at 19:45
  • 1
    $\begingroup$ Have you tried asking the authors? $\endgroup$
    – MBaz
    Oct 1, 2020 at 2:15
  • $\begingroup$ Okay, I'll try asking Paul sometime $\endgroup$ Oct 1, 2020 at 19:53

1 Answer 1


I haven't looked at the reference yet , but just to answer the question, yes filtering is performed prior to down sampling to avoid aliasing back in the out of band signals. However if your signal is already appropriately bandlimited you could forego the filter entirely. There's various reasons you might want to do other, unrelated, filtering after the downsampling operation. In fact, doing such filtering after the downsampler is preferable due to the lower sample rate and thus lower computational complexity.


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