[sdiy] physical modelling

[Grant Richter]

> 
> If you get homesick... you could sum in some pseudo-random noise from
> a shift register, and then limit the output to about seven bits... to get an
> "authentic" sound.   ;^P
> 

Now that we are starting to get a handle on information entropy in audio. I
can clear up this misconception.

Information entropy is measured in "bits" and is an index of the minimum
number of bits needed to encode a specific symbol set. So a continuos time
undigitized analog signal represents the maximum information entropy level.

ANY process of quantization or time sampling will reduce the information
entropy by reducing the size of the symbol set. This is something that CAN
be documented mathematically.

Additionally, the finite speed of the human nervous system represents a time
sampling effect at the ear itself. So the very process of "hearing"
represents a reduction in information entropy. It may be possible to
quantify that reduction in "bits" by estimating the number of possible
symbol states of the cochlea. That is the number of nerve endings running to
the cochlea itself, represent the fundamental symbol states of auditory
perception. So the theoretical resolution of hearing in "bits" CAN be
calculated to some extent.