[Dick Pierce[_2_]]

wrote:

Second, there really isn't that much to measure. An audio signal,
like all electrical signals, has only two attributes: amplitude and
frequency.

Actually, to be moe precise, the two fundamental attributes are
ampliude and time, but your point remains: it's not that it's
some higher-order dimensional thingy with some of those dimensions
hidden. From the amplitude vs time signal we can derive other
information such as the amplitude vs frequency your mention.
Two ways come to mind of doing this: through various mathematical
transforms or through a process called hearing.

Extended to a DAC or a typical power amplifer, this two-dimensional
pr0oblem becomes a three-dimensional one: the amplitude of the right
channel and the amplitude of the left channel vs time (we assume the
two channel use the same time :-). There's nothing else going on,
there is no other "hidden channel" for "hidden information."

But NONE of this is a mystery, at least not to those in the signal
processing, acoustical/psychophysical realm.

It may well be a mystery (and often times seems like it is) to those
in high-end audio. But, I'd assert, that's an education problem.

--
+--------------------------------+
+ Dick Pierce |
+ Professional Audio Development |
+--------------------------------+