1
$\begingroup$

I understand decibel = 20 * log (magnitude/reference value). To truly appreciate the meaning of this, if I have a single frequency tone that corresponds to a certain FFT magnitude shown on a PC that's constantly recording. If I lower the tone volume by 20 dB (say, by monitoring with a SPL meter), then I should see the FFT magnitude that's 1/10 of its previous value right?

I'm only trying to understand this from a theoretical perspective, ignoring complicating real life factors.

Thanks

$\endgroup$
2
$\begingroup$

-20dB corresponds to $1/10$ of the amplitude or $1/100$ of the energy. That's the same thing, since energy (all else being equal) is proportional to the square of the amplitude.

It also corresponds very roughly to about $1/4$ perceived loudness but that's an entirely different can of worms

$\endgroup$
  • $\begingroup$ yes, I meant 1/10 of FFT amplitude. Thanks $\endgroup$ – user173729 Aug 6 at 14:55

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.