[PD] dbtorms amplitude scaling sounds wrong

Mathieu Bouchard matju at sympatico.ca
Tue Mar 1 17:23:52 CET 2005

On Tue, 1 Mar 2005, Stefan Turner wrote:
> > Anyway, adding 6dB on to the level will not make it
> > sound twice as loud, 
> > that's for sure!
> After some searching I just found that apparently
> +10dB is meant to correspond to doubling loudness, in
> case anyone's interested. Apologies for a rather
> stupid question: I think I finally understand dB now
> at least...

+10 dB means wattage amplitude multiplies by 10.
+20 dB means wattage amplitude multiplies by 100,
   and means voltage amplitude multiplies by 10.

watts = ohms * volts^2.

10 dB * log(2)/log(10) = 3.0103 dB is a doubling of wattage amplitude.
so 6.0206 dB is a doubling of voltage amplitude.

Usually, loudness (perceptual) is quite proportional to the logs of
electric/sonic amplitudes, but in the very quiet range things are
different, as some things are "rounded" as being "silence" by the ear
(silence in dB is minus infinity).

Mathieu Bouchard -=- Montréal QC Canada -=- http://artengine.ca/matju

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