From: Philipp Pertermann <perterm_at_vce.de>
Date: Tue, 28 Nov 2006 11:16:22 +0100

Paul Louden schrieb:
> In that context, 90% could actually be considered the same as
> -10%, as they're both "10% less than the full level" but since you don't
> have an absolute point of reference with dB, the negative numbers make
> perfect sense.

Actually you do have an absolute point of reference: a full scale swing
of the signal. That's why it is called dbfs. But you are right that this
doesn't mean an absolute volume level as perceived by humean ears. That
is measured by db spl (sound pressure level), an other kind of decibel.
That describes the sound pressure relative to a sound that produces a
pressure change of 20uPa.

What a pity that rockbox can not scale the volume in db spl. That's
impossible because it depends on the headphone and probably even on how
well the headphone fits into the ear.

Phil
Received on 2006-11-28