THE NOISE-GATE 

     A noise-gate, in electronics, is a VCF driven by an RMS level
detector.  VCF is short for "voltage-controlled  filter;" an RMS
level detector simply determines the root-mean square of the
amplitude, its average power and not the peak power.  The function
of an RMS level detector in the circuit is to determine input
levels so the filter can decide how much filtration to apply.  High
frequencies, which contain more noise than low frequencies (tape
hiss) are filtered more, in a sliding-gate fashion, because as
signal drops off noise becomes more audible.  Low frequencies may
also be filtered in a noise-gate:  one manufacturer had a gate
which filtered, not only the highs, but the lows, to deal with
turntable rumble. 

     Because hiss is most audible at low levels and drowned by
signal at high levels, and since low-level audio signals usually
have very few harmonics, it is possible to filter all frequencies
above, say, 1 Khz and gradually turn the filter off as the signal
level increases so that there is a subjective improvement in sig-
nal-to-noise ratio even though information (in the Shannon-Weaver
sense) is being removed. 

     The analogy between frequency response and amplitude and what
is going on at any given level of organization is probably that
low-frequencies are slow-mutating systems (mutation in any "unit
of selection," not merely the biological) and high frequencies are
rapidly mutating ones.  Amplitude is the extent to which the
information-content of the mutation is large or small compared w/
its predecessors. 

     A noise-gate is what is known in electronics as an open-loop
noise-reduction system:  it can be used to reduce noise in a signal
which has not been encoded; companders, which will be covered
elsewhere on this web-page, are closed-loop devices:  a signal is
first encoded and then decoded. 

     The simplest possible mechanism for signal-processing is a
static filter, not a noise-gate, because a filter which does not
slide is the simplest possible type of filter to make, even though
it removes all information above or below a given frequency. The
analog in audio is a high-filter for removing hiss, which though
it causes a subjective improvement in the signal (no more hiss)
also causes a subjective degradation in the signal because some of
the sound is missing, only "distortion-tolerance" in the human ear
allows one to take the subjective degradation with the subjective
improvement in a static filter.  The subjective effect of the
noise-gate is much more pleasing to the ear, even though it is also
a form of distortion.

     One way in which a noise-gate could function in the esthetics
of literature is in the filtration that goes on in genre literature
as opposed to the "classics" (that art which appeals most strongly
to academic critics) is that a literary genre is very much like a
noise-gate:  It allows small mutations to turn off the filter of
"formula" slightly as they pass by.  An antiformulaic work will
usually be selected against, but sometimes will "open up" the gate
and start a whole new genre.  [Adventure, Mystery, and Romance,
John Cawelti, University of Chicago Press, 1976.]   

     In fact, this may be what William Gibson did when he wrote
NEUROMANCER:  winner of every major science fiction award for the
year it was published.  It founded the new genre of cyber-punk,
which in fact seems not only to have opened the field to much
innovation, but to have established its own genre in its own right.

     This depends to what extent the elements in NEUROMANCER are
truly new.  For example, in the Timothy Leary interview with
William Gibson in MONDO 2000, Gibson was quoted as stating that his
work was highly influenced by William Burroughs, though none of the
"cut-ups" or "word-collages" that Burroughs is famous for are
present.  "Cut-ups" was Burroughs' term for a technique whereby
he'd take pieces of his own work, pieces of someone else's work,
fold the pages, cut holes in them, and lay them one over the other
so that new patterns of words would appear.  His "word-collages"
were usually done on record albums where he'd take bits and pieces
of dialogue and cut up the tape so that the words would form new
sequences. 

     Such techniques are hardly amenable to the mass market.  What
Gibson did was take the drug-soaked atmosphere of Burroughs'work,
combine it with elements of the street scenes in the movie
BLADERUNNER, which in turn was based on the classic Philip K Dick
novel DO ANDROIDS DREAM OF ELECTRIC SHEEP? and combine it with
elements of mystery and intrigue--again, that classic Trinity,
Adventure, Mystery, and Romance, though the cowboy (cyber-slang for
hacker's) hero's romance seems almost more sadomasochism than a
romance--but that again is a Burroughs-esque element.

     The point is that Gibson's work may be the opening even as we
witness the revolution in computer technology which he was writing
about in the latter decade of the 20th Century and into the 21st. 

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