On Sat, 24 Feb 2007 16:37:46 GMT, "Henry Kolesnik"
wrote:
I understand the octave which relates to the doubling of pitch, cent
which is 1/1200 of an octave. Cents are used in tuning and the good
ears can tell a diference of about 3 cents. My imagination seems
limited in understanding what's so great about plotting on log-log
paper. And why is the knowledge of sound decades so limited? From 30
to 15,000 Hz there's 2.7 decades, 8.97 octaves and too many cents. The
book points out that all visible light is one octave making the audible
spectrum much more complicated if you look at it from that standpoint.
In a multiband shortwave radio each band is approximately an octave
because that's all a LC circuit can span.
The octave is a musical convenience - we all recognise it and it is
the natural interval on which all scales are based. Being power based
rather than linear, it is a logarithmic scale. So much is easy enough.
The decade is an artifact, based on the fact that we are a ten-based
species. It has no greater significance than that it fits nicely with
our mathematical norms. It is something we have come to accept as the
natural order, even though it is no such thing.
So why use log/log paper? The frequency axis is log because that is
how music and out appreciation of pitch works. The vertical scale is
log (dB0 because that is how our appreciation of loudness works -
roughly. You could use a linear vertical scale, but then if you
encompassed the loudest sounds, the small detail would be invisible.
So a log decibel scale makes sense.
Why decade paper? Because we have ten fingers.
d
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