Test: hard returns, 75 characters (paraphrase of some Rothenberg)

The model concerns a code that can be used to extract information from huge
stimulus spaces despite the limitations of the human memory system...

We have hypothesized that when a listener is presented with a
series of unfamiliar tonal stimuli, he must mentally construct a
reference frame, P, to which all such stimuli are referred. Many
proper P maysatisfy this requirement. If the stimuli are
sufficiently unfamiliar (as when one listens to music of an alien
culture) many repeated hearings may be necessary during which a
listener replaces a familiar P with one more appropriate for
classifying the stimuli heard. The cardinality of the constructed
P will depend upon the numbers of distinctions required by the
particular musical language or, if the stimuli are not musical,
upon the fineness of discrimination required by the recognition
task to be performed.

Once an appropriate P has been found, the next step is to locate a stimulus
within it...

Given any "interval" (pair) in P, the listener is able to
recognize the possible positions its elements might occupy in P.
In effect, given any pair of elements he can mentally supply
(interpolate) a possible set of remaining elements of P which
satisfy the equivalence class and tuning he has learned. Such an
interpolation becomes unique after a sufficient number of elements
of P are heard. This is equivalent to the identification of x
(key) in a give P(x).

For example, the major triad [C E G] is not a sufficient subset of
the C-major scale since there are two other major scales (namely G
and F) in which it occurs. But C-major is the only major scale
which contains the four notes [G B D F], so the "dominant seventh
chord" is a sufficient subset of C-major. A minimal set is a
sufficient set with no sufficient subsets. Thus, [G B D F] is not
a minimal set, but [G B F] is, as there is no major scale except C
which contains [G B F], while each of its proper subsets [G B] [G
F] [B F] are included in some other major scale (G, F, and F#
respectively).

It is straightforward to verify that sufficient (and therefore
minimal) sets are invariants of equivalence. They depend only on
the equivalence class, not on the particular tuning.

A measure is developed for this locating...

Consider a language whose alphabet consists of n letters (or
phonemes). How many distinct words can be formed using this
alphabet? Certain restrictions may exist which can limit the
sequences of letters that can occur. The more distinct words that
can be formed whose length is less than or equal to some maximal
value, the more efficient the alphabet is said to be.

A similar situation applies when "words" are formed from sequences of
intervals. Since interval sequences are formed from tone
sequences, we consider sequences of the elements of some P. Also,
since no new intervals are formed when an element is repeated,
only non-repeating sequences will be considered. Since we are
here concerned only with properties deriving from the structure of
P, we will use the following criterion for the termination of a
"word" (other criteria apply when "motifs" are considered): When
all remaining elements of P are determined by a sequence of some
of its elements, the addition of elements will impart no further
information of this type, and the "word" will be considered
terminated. That is, any sequence will be considered complete as
soon as a sufficient set occurs in it.

We now ask, given a particular equivalence class, how many
distinct words can be formed using k elements where k varies from
1 to n. Consider all non-repeating sequences of n points (there
are n! such sequences). Let S_i be the number of elements in each
such sequence which must appear before a sufficient set is
encountered. The F(P) is defined as the average,

n!
Sigma(S_i) / n!
i=1

F(P) may be interpreted as the average number of elements in a non-
repeating sequence of n elements of P(x) required to determine the
key, x. Efficiency, E, is defined as F(P)/n and Redundancy, R, as
1 - F(P)/n. Both numbers lie between 0 and 1.

It should be noted that this kind of efficiency and redundancy
differs from the meanings these terms assume in information
theory. The distinction is important and applies to alphabets in
spoken natural languages as well as to musical scales. The
redundancy of information theory refers to a redundancy in the
message, not in the code. In our discussion here, that property
of the code which determines whether efficient messages _can_ be
constructed (if such are desired) is considered. This property is
inherent in the code itself, and does not apply to the message.

Rothenberg outlines six scenarios...

Scale type Stability Efficiency
(a) proper high high
(b) proper high low
(c) proper low high
(d) proper low low
(e) improper ---- high
(f) improper ---- low

And discusses them...

Notice that in Figure 1, all scales in 12tET with which we are
most familiar (the major, minor, and Chinese pentatonic) conform
to situation (a). In fact, the major scale (of which the
"natural" minor is a mode) is far higher in both stability and
efficiency than any other 7-tone scale. Next among 7-tone scales
is the "melodic" minor (2,2,2,2,1,2,1). The Chinese pentatonic
stands out among scales of 5 and 6 tones.

However, situation (b) applies to many scales with which we are familiar,
such as the "whole-tone" and "12-tone" scales. Note
that while these are strictly proper scales, from the hearing of a
sufficient set (any element) alone, it is not possible to code the
elements of P into scale degrees. That is, although PxP is coded
by the proper mapping, there is no way to index elements of P
except by arbitrary choice. __Thus, since in these cases
intervals are coded but tones are not, composition with these
scales must involve relations which make use of motivic
similarities rather than relations between scale degrees.__ Hence
the tone row basis of 12-tone music (which is essentially motivic
in concept) is not surprising. An examination of Debussy's whole-
tone piano prelude "Violes" show similar motivic dependency.

Now consider improper scales. PxP is not coded except by the
employment of proper subsets or a fixed tonic. __Hence
information is primarily communicated by the scale degrees.__
Thus it is important that P be coded as quickly as possible, which
is indicated by a high redundancy (low efficiency) as in case
(f). It would be expected that scales characterized by case (e)
would be extremely difficult to use, except when the tonic is
fixed by a drone or similar device and, in fact, we have not
discovered such scales in any musical culture examined thus far.
In general, the use of motivic sequences on different scale
degrees of improper scales would not be expected (except within
proper subsets of such scales), and this is strongly supported by
examination of Indian and other music using improper scales.

We would also expect that proper scales characterized by low
stability would tend to be used as improper scales, so that case
(c) would resemble case (e), and (d) resemble (f), and similar
remarks apply.

Makes cross-cultural observations...

In Java there exist two scale systems, "Slendro" and "Pelog", each
containing a variety of scales. It has been observed that all
scales in the "Slendro" class are strictly proper and that all in
the "Pelog" class are improper. In a study conducted with the
assistance of Mr. Surya Brata of the Ministry of Education and
Culture, Jakarta, the uses of these scale systems were observed to
be in accord with the predictions of this model.

References to the Javanese study...

Kunst, J. (1949), _Music in Java_, The Hague; Martinus Nijhoff.

Hood, M. (1954), _The Nuclear Theme as a Determinant of Patet in
Javanese Music_, Groningen, Djakarta: J.B. Wolters.

Hood, M. (1966), "Slendro and Pelog Redefined", Selected Reports,
Institute of Ethnomusicology, University of California at Los
Angeles.

Does anybody know anything about these references?

-C.