On Dec 6, 2007 1:39 AM, Richard Dobson <richarddobson@blueyonder.co.uk> wrote:
>
> Chuckk Hubbard wrote:
> > Don't you mean that amplitude values in Csound are linear, and
> > decibels are not linear?
> >
> > Actually decibels still throw me.  I am perfectly fine with computing
> > simple logarithmic amplitudes in my head; and to have such a wide
> > dynamic range expressed in 6 units seems limiting.  I guess I just
> > outed myself as never having used much studio equipment...
> >
> > -Chuckk
> >
>
>
> This is one of the most common questions in digital audio and..

Well, it wasn't really a question.  I know how decibels work, I just
think they get really soft really fast.  To my ear, yes, .1 is pretty
quiet.

> is why so much computer music has such a narrow dynamic range.

Along with compressors and cut-and-paste hotkeys, no?

> "Linear" signifies the way a graphic scale is presented - equal distance
> = equal difference. The musical frequency scale (in Hz) is linear - the
> differences between 220 and 440, and between 440 and 660, are the same
> (220). But the ~ratios~ are different, hence the interval they represent
> is different. So pitch is described over a logarithmic scale (same
> ~ratio~). Intensity can be measured similarly in either way.

I also prefer to work with frequency ratios over notes.  It's true
that the perception of intervals is good and logarithmic, but the
relevance of the harmony:
4:4
5:4
6:4
7:4
is easily seen, as opposed to C, E, G, Bb- (or whatever notation for
the harmonic 7th).  And the linear nature of the harmonic series is
evident in this representation.  I have heard several teachers and
many students remark that the notes in the harmonic series "get closer
and closer as they get higher."  But if you graph them on a linear
frequency graph you see they are all equidistant, and their
relationship is obvious.

> *  covering the top half of the slider range would only reduce power by 6dB
> *  equal-distance slider movements will not result in equal-sounding
> loudness changes

I have been advocating a similar approach to tempo change, to no avail.
I.e. if tempo starts at a and ends at b, over B beats, then after B/2
beats it would be at (b/a)^(1/2) * a.

> ~Much~ better to represent all amplitude values in dB, and let Csound
> convert it to the often very small raw amplitude levels. Much easier to
> write -30 than 0.031 (approx) and, I suspect, more ~meaningful too! In
> an amplifier or mixer, all the volume controls (faders etc) use a
> "log-law" potentiometer to achieve this - a "linear" pot would be awful.

I usually let my ear decide what values to use, and, like I said, I'm
quite accustomed to dividing in my head.  But, I suppose it's
inevitable, I will have to go along with the herd.  Might's well start
using decibels.

-Chuckk

-- 
http://www.badmuthahubbard.com