 |
Description  |
|
|
FIELD OF THE INVENTION
The present invention pertains to electronic musical instrumentation. In
particular, the invention pertains to methods and apparatus for rendering
the music selected by a performer in accordance with a preselected playing
style.
BACKGROUND AND SUMMARY OF THE INVENTION
Various systems exist in the prior art for deriving accompaniment notes
that enhance a melody in accordance with the selected harmony. Pending
U.S. patent application Ser. No. 274,606 discloses a substantial
improvement over prior art enhancement techniques that were, in general,
hampered in the selection of accompaniment notes by limitation to a
preselected musical compass below the melody note.
The art existing prior to the method and apparatus disclosed in the
referenced patent application was thus unable to utilize advantageous
non-chordal or non-scale tones when such tones were not explicitly sounded
by the musician. Such a drawback becomes particularly critical when a
musician of limited playing ability and/or dexterity seeks to sustain an
accompanying chord with only a minimum number of tones. The invention
described in the referenced application incorporates some significant
aspects of musicianship into the automated instrument art by providing a
system in which accompaniment notes are derived on the basis of the
harmonic relationship between the melody and the selected chord. Briefly,
the invention disclosed in that application achieves enhanced
harmonization through the use of a plurality of listings of accompaniment
notes in tables suitable for data processing. Data storage requirements
are minimized through the utilization of a system of accompaniment note
identification based upon musical transposition.
The aforementioned system and other harmony supplementation methods and
apparatus of the prior art, while greatly enhancing the quality of the
performed work, often betray their mechanical or electromechanical origins
resulting in somewhat of a tradeoff between the improved harmonization
achieved and a loss of realism due to the exactness with which the music
is performed. This can sometimes result in a mechanical and unappealing
musical texture.
The above-stated deficiency of prior art harmonization systems arises from
the failure of such systems to recognize and incorporate the qualities of
musicianship which lend character and realism to the performance of a
skilled musician. For example, automatic harmonization systems
conventionally sound the entire set of selected accompaniment notes at a
single time. This generates an overall musical effect which differs from
that one would expect from a skilled performer and/or orchestra. Skilled
musicians add "style" to their performances by sounding accompaniment
notes in various formats including sequences rather than simultaneous
soundings of accompaniment notes. Further, a group of musicians, however
skilled, will rarely, if ever, achieve the type of synchronization which
commonly characterizes orchestrations performed by means of an electronic
organ.
Attempts have been made in the prior art to enable an instrument, such as
an electronic organ, to emulate techniques performed by a skilled musician
to add realism and musicianship to the performance. The adaptation of
various orchestrations by an electronic organ has been enhanced by prior
art systems which in fact attempt to incorporate characteristics
associated with the style of play of a selected instrument. Thus, the
addition of the feature known as "automatic reiteration" to an organ
incorporating banjo instrumentation overcomes, to some degree, the
difficulty inherent in attempting to make an organ voiced to sound like a
banjo (and played as an organ) make a convincing replica of a banjo being
played. In automatic reiteration, all of the sounded notes, both melody
and accompaniment, are repeatedly keyed.
Another technique which enables the performer to create a more realistic
effect is the technique known in the organ industry as "delay vibrato".
This technique is particularly appropriate in the playing of a violin
where the performer holds a sustained note for a period of time,
thereafter rocking his fingers to cause a vibrato effect. Electronic
organs employing this effect commonly wait until the player sustains a
note for a period of time before adding the electronic vibrato effect.
The foregoing systems which add realism to a performance by electronic
organ, deal with each of the notes struck by the performer whether melody
or fill note in a uniform manner. While the addition of such features aids
a few of the common playing techniques, such treatment is simplistic in
light of the broad range of musicianship which cannot thereby be
adequately performed.
Very desirable musical effects result from the modification of the
harmonizing notes in a manner independent of the melody note or any
modification of the melody note. Three popular playing styles which rely
upon the sequential soundings of harmonious accompaniment notes during the
hold down period of the melody are known as "country piano", "strum" and
"accordion" (or "tremolo").
The country piano style has evolved from the attempts of pianists to
emulate the sounds of the fiddle and the mandolin, instruments whose
strings are tuned in consecutive fifths. One technique according to
country piano style is typified by the popular performer Floyd Cramer.
This style is characterized by the addition to the melody of a single
accompaniment note, as an appoggiatura, to a second accompaniment note
chromatically adjacent to or separated by one or more chromatic tones. The
melody note is not affected by the change of accompaniment notes. The
appogiatura note is typically a short note while the sustained
accompaniment note is held for the remainder of the melody. To avoid a
monotonous musical texture, the skilled musician is selective in his use
of this effect applying the technique in a sparing manner for maximum
musical impact.
A strum effect may have one of a number of recognized forms in which
different accompaniment notes are struck non-simultaneously and held. In
the instance of a guitar-type strum, the accompaniment notes are generally
sounded sequentially, either up or down in pitch, for preselected time
periods before an additional accompaniment note is sounded.
A type of strum may be advantageously applied to orchestrations involving a
number of instruments. In the playing of a musical piece, different
performers, although seeking to synchronize with each other, will
inevitably sound their instruments at differing points in time. Thus, an
automatic harmonization technique wherein a plurality of accompaniment
notes are sounded at slightly different points in time and held add a rich
and realistic texture to the resulting music.
Tremolo emulates a technique often performed by accordion players. Such
technique is accomplished by alternating two harmonious accompaniment
notes as the melody note is sounded. This effect, which is done to break
the monotony of sustained melody notes, often occurs as other
accompaniment notes are held with the melody note.
Thus, highly advantageous musical effects may be realized by the
implementation of automatic techniques and apparatus for effecting the
sequential sounding of a plurality of harmonious accompaniment notes as a
melody note is sounded. The present invention overcomes the disadvantages
of the prior art and achieves the aforesaid advantageous result by
providing, in a first aspect, a method for embellishing a melody selected
by a performer in conjunction with a chord according to a predetermined
musical style. The method, accomplished by the instrument itself, includes
the steps of deriving a plurality of accompaniment notes, each of the
notes being based upon the harmonic relationship of the melody to the
chord and sounding the accompaniment notes in a preselected format to
effect the predetermined musical style.
The invention provides, in an additional aspect, a method for embellishing
a melody selected by a performer in conjunction with a chord, according to
a predetermined musical style. The method, accomplished by the instrument
itself, includes the step of deriving a plurality of accompaniment notes,
each of such notes being based upon the harmonic relationship of the
melody to the chord. More particularly, plural groups of accompaniment
notes are provided, each of such accompaniment notes being associated with
a chord and melody. The method further proceeds by the step of selecting
at least one accompaniment note from each of the groups according to the
melody and chord selected by the performer. The final step comprises
sounding the accompaniment notes in a preselected format.
In a further aspect, the invention provides a method for deriving a
plurality of signals in response to a melody note signal and a chord
signal, the plurality of signals representing a corresponding plurality of
accompaniment notes harmonically related to the melody note and to the
chord and temporally related to effect a predetermined musical style. The
method includes the step of storing a plurality of groups of listings of
accompaniment notes. Each of the listings of a group corresponds to a
chord type and provides at least one accompaniment note harmonically
related to each melody note of the chromatic scale with respect to the
chord type. The groups are arranged so that the listings of accompaniment
notes for a particular musical chord type are related from group to group
in accordance with the predetermined musical style. At least one
preselected constant time value is provided and associated with at least
one of the groups of listings. The root and type of the chord are then
derived from the chord signal. The melody note is derived from the melody
note signal. Listings are selected from the plurality of groups in
accordance with the type of the chord. At least one accompaniment note is
then located in each of the listings according to the chord root and
melody note. Thereafter, a plurality of accompaniment note signals is
sequentially generated, each of such signals being responsive to at least
one accompaniment note of a selected listing, at least one of the signals
having a duration corresponding to the constant value associated with the
group from which it is derived.
In yet another aspect, there is provided apparatus for embellishing a
melody selected by a performer in conjunction with a chord according to a
predetermined musical style. Such apparatus includes means for deriving a
plurality of accompaniment notes. There is also provided means for
sounding the accompaniment notes in a preselected format.
These and other objects, advantages and features of the present invention
will appear for purposes of illustration, but not of limitation, in
connection with accompanying drawings wherein like numbers refer to like
parts throughout and wherein:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a system schematic view of the present invention;
FIGS. 2a and 2b present schematic diagrams of the upper or melody and the
lower or harmony keyboard input circuitry, respectively, of the present
invention;
FIG. 3 is a schematic diagram of a first embodiment of the output circuitry
including output tone switching apparatus and voicing and mixing circuitry
of the present invention;
FIGS. 4a and 4b present a logical schematic and a pin diagram,
respectively, of the microcomputer of the present invention, showing the
microcomputer functions and pins utilized in the present invention;
FIGS. 5a through 5c are flow diagrams illustrating the operations and
computations utilized by the present invention in the implementation of
the country piano, strum and accordion or tremolo musical styles,
respectively;
FIG. 6 is a schematic diagram of an alternative embodiment of the output
circuitry of the present invention. The circuitry of this figure
incorporates an orchestration capability into the system of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings, FIG. 1 is a diagram of an electronic organ
system incorporating the present invention. In it, an upper ("melody")
keyboard 10 and a lower ("harmony") keyboard 12 provide conventional means
for playing the instrument (i.e., for manipulation according to the
techniques of musicianship) and for the application of data to the system.
The data is processed according to the methods disclosed herein. Such
methods rely in part upon the teachings of U.S. patent application Ser.
No. 274,606 of the inventors wherein the musical principle of
transposition is utilized to derive and sound appropriate accompaniment
notes from a preselected set of accompaniment note tables.
Keys 14 are arranged to correspond to standard musical scales and are
assigned ordinal numbers for data-processing purposes. Separate melody and
harmony keyboards are provided according to FIG. 1. The present invention
may also be practiced by means of an organ system utilizing a single
keyboard. It will also be noted that the selection of harmony may be
achieved by means of a conventional button-type chord selector. In the
event such chord selection apparatus is employed, it will be appreciated
that the chord detection apparatus and method disclosed infra may be
bypassed in implementing the system herein.
A switch is associated with and activated by the application of pressure to
a number of the keys 14. Each such switch assumes a first state and, upon
the performer striking an associated keyboard key 14, a second, opposite
state. In the embodiment of FIG. 1, wherein "low true" input logic is
employed, the closing of such a switch by striking its associated key 14
causes the application of a positive voltage +V through a pull-up resistor
to a preselected storage location in a shift register (as discussed in
connection with FIGS. 2a and 2b) to cause the storage therein of a logic
"zero".
The data generated by the manipulation of the keyboards 10, 12 is applied
in parallel fashion over a melody bus 16 to the upper or melody keyboard
register 20 and over a harmony bus 18 to the lower or harmony keyboard
register 22. As will be discussed, the registers 20, 22, which are
controlled by signals from a microcomputer 28, include shift registers for
the storage of successive musical frames defined by the states of the sets
of the switches associated with keys 14 depressed at a given instant of
time. The frames of data are read out of the registers by the application
of clocking pulses from the microcomputer 28. Each of the registers 20, 22
thereby provides playing data, in registration corresponding to the
relative locations of the keyboard notes, to the random access memory
(RAM) of the microcomputer 28 by means of serial bit streams transferred
along a melody conductor 24 and a harmony conductor 26. A timing crystal
29 aids the various functions of the microcomputer 28.
A preferred embodiment of the present invention utilizes an Intel 8048
microcomputer, a programmable device manufactured by the Intel Corporation
of Santa Clara, Calif. A detailed discussion of the system operation of
the microcomputer 28 will be undertaken with regard to FIGS. 4a and 4b.
For the present, it will suffice to say that the microcomputer 28 is
specifically adapted in the present invention to control the various
functions of the organ system.
Data representative of the accompaniment notes generated is provided to
output tone switching circuitry 34 by the data bus 32. The output tone
switching circuitry 34, which is controlled by the microcomputer 28
includes alternative embodiments illustrated in FIGS. 3 and 6 comprising
further novel features of the invention. In the embodiment of FIG. 6, an
orchestration capability is achieved. After processing within the output
tone switching circuitry 34, resultant analog signals are applied along a
bus 36 to voicing and mixing circuitry 38. The circuitry 38 provides an
analog waveform for an amplifier 40 which, in turn, feeds the amplified
analog signal to a conventional speaker or speaker system 42 to sound the
desired music.
FIGS. 2a and 2b present in greater detail the input (melody and harmony)
systems of the organ. In FIG. 2a, the upper ("melody") keyboard circuitry,
it can be seen that the upper keyboard register 20 includes a plurality of
shift registers 46, 48, 50, 52, 54 which communicate with the melody
keyboard 10 via the melody bus 16. A plurality of conductors 44 provides
electrical connection between a positive voltage, +V, common to each of
the keys 14, and an associated location of one of the selected shift
registers 46-54 through a corresponding plurality of key-activated
switches 15. It will be noticed that the melody keyboard 10 includes only
37 keys. This reflects the fact that, although the standard spinet organ
keyboard includes 44 melody keys (F1 through C4), the lower seven keys
(i.e., F1 to B1) are not sampled to allow, in the invention, the sounding
of a number of accompaniment notes below all melody notes processed. Thus
the accompaniment note generation technique of the present invention is
not responsive to the potential depression of these lower-scale melody
tones. As a reflection of the limited melody input from the keyboard 10
and the utilization of five eight-bit shift registers (each of which may
be, for example, a DC 4014B manufactured by the Radio Corporation of
America of Princeton, N.J.), the first three locations of the register 46
are tied to a common positive voltage which, for the "low true" input
logic employed, corresponds to a logic "zero".
The control bus 30 applies clocking and latching functions to the upper
keyboard registers along conductors 62 and 64, respectively. A clock pulse
is applied to the registers upon the completion of each melody note
computation cycle of the microcomputer 28 (discussed infra). Its
application enables the registers 46-54 to retain the data input from the
keyboard 10 until forty-four clock pulses have arrived from the
microcomputer 28 to read an entire frame of melody data into the
microcomputer.
FIG. 2b is a detailed illustration of the lower ("harmony") keyboard input
circuitry. The harmony keyboard 12, the output of which is utilized to
identify the chordal-type selected by the musician, also includes a
plurality of switches 15, each associated with a single note, for
connecting a positive potential +V to preselected locations of shift
registers 68, 70 which comprise the lower keyboard register 22. The organ
utilizes a harmony keyboard 12 of twenty-eight keys. Unlike the situation
discussed with respect to the melody keyboard 10, it can be seen that the
twenty-eight outputs of the keyboard 12 are cross-connected in a reducing
matrix 66 so that the harmony bus 18 applies only twelve independent,
parallel outputs to the registers 68, 70. Corresponding thereto, the first
four inputs 72, 74, 76, and 78 of the eight-bit shift register 68 are
wired directly to a positive voltage, storing logic "zeros" in the
corresponding shift register locations.
Thus, although the harmony keyboard 12 comprises twenty-eight tones
arranged in order of ascending frequency, left to right, from the lowest
tone (A1) to the highest tone (C3), the reducing matrix 66 assures that
the content of the shift registers 68, 70, comprising the lower keyboard
register 22, will not reflect the octaval origin of the applied tones.
Such simplification of circuitry eliminates harmonically redundant
information from the data input of the system. It will be apparent to
those skilled in the art that this simplification of data consequently
reduces the electronic complexity of the device. The discarding of octave
information with respect to the harmony keyboard's input is permitted
since chordal identification as to both type and root is independent of
octave when determined according to the teachings of the present invention
and those of U.S. Pat. No. 4,248,118 of George R. Hall and Robert Hall,
for "HARMONY RECOGNITION TECHNIQUES". The teachings and content of this
patent, the property of the assignee herein, are hereby incorporated by
reference.
As was the case with respect to the upper keyboard register 20, the shift
registers 68, 70 of the lower keyboard register 22 receive control signals
from the microcomputer 28 by means of the control bus 30. More
particularly, the clock line 62 and the latch line 80 control the shift
registers 68, 70 in a fashion analogous to the control of the upper
keyboard register 20 by the microcomputer 28. The clock line 62 provides
identical clocking to the shift registers of the upper and the lower
keyboard latches while the melody and harmony shift registers are
individually latched by signals carried along the conductors 64 and 80.
Referring now to FIG. 3, there is shown a detailed schematic view of output
circuitry according to the invention. It includes the interacting output
tone switching circuitry 34, voicing and mixing circuitry 38, output
amplifier 40 and speaker 42 disclosed in FIG. 1.
The output tone switching circuitry 34 includes six eight-bit
serial-to-parallel converters 84, 86, 88, 90, 92, 94, the last four
locations of which are unresponsive to incoming data. Each of the
converters 84-94 may be a CD 4094 manufactured by the Radio Corporation of
America, essentially a combination shift register and buffer-latch. A
stream of forty four bits of data, generated by methods to be discussed,
is clocked along the conductor 95, which provides electrical connection
between the converter 84 and the microcomputer 28, into the forty four
utilized locations of the six eight-bit converters. The bits are clocked
into the converters 84-94 by the PROG clocking pulses of the microcomputer
28 which are applied along the conductor 62. Each PROG pulse is toggled by
the execution of an OUTPUT instruction within the microcomputer 28. Hence,
it will be seen, each bit of data generated by the method shown in FIG. 5
is appropriately clocked into the converters 84-94. A latching pulse,
provided through the conductor 96, initiates the "dumping" of the data,
which has been clocked serially into the converters, along forty four
parallel conductors 98. The latching signal is generated upon the
affirmative interrogation of a loop counter (the countdown register R4 of
the Intel 9048 microcomputer, discussed infra). Affirmative interrogation
indicates a system determination that all thirty-seven melody notes of the
input have been processed. (Although there appears to exist a discrepancy
between the length of the input melody keyboard 10 and the number of tones
generated by the output circuitry, one must keep in mind the fact that
derived accompaniment notes supplement the tones "called up" by the
playing of the input keyboards.)
The forty four parallel outputs applied to the conductors 98 represent
forty four independent keying signals. Each keying signal is in turn
applied to an AND gate 100, the other input port of which is tied to one
of forty four tones generated from a standard organ oscillator system (not
shown). The keying pulses applied to the AND gates 100 pass the tones
therethrough. Each output of an AND gate, a single frequency analog
voltage signal conveying one musical pitch, is applied to the conventional
homogeneous voicing and mixing circuitry 38. The circuitry 38 includes
standard organ filters and related mixing circuitry, by means of which the
individual keyed tones from the AND gates 100 retain tonal integrity as
they are combined into a composite signal. The resultant signal is applied
to the output amplifier 40 and finally to the speaker 42 which acts as an
electro-audio transducer, translating the analog signal into sound.
FIGS. 4a and 4b are detailed illustrations of the microcomputer 28 which
supplies the various control functions of the present invention. FIGS. 4a
and 4b use the nomenclature of the Intel 8048 microcomputer chip. In the
event a more general appreciation of the details of this machine and its
functions may be desired, one can refer to MCS-48 Microcomputer User's
Manual published by the Intel Corporation of Santa Clara, Calif. (1976).
This invention is by no means limited in implementation to this particular
microcomputer 28 nor, in fact, to any device, programmable or otherwise,
as a control mechanism. Extensive reference to the Intel 8048 is made only
for the purpose of illustration and as a basis for reference to the
interworkings of the programming schemes illustrated in FIGS. 5a, 5b and
5c.
FIG. 4a presents the logical functions of the eight-bit Intel 8048 single
component microcomputer which relate to the invention. FIG. 4b illustrates
the pin configuration of the Intel 8048 employed for the reduction to
practice of the invention herein.
Referring concurrently to the above-referenced figures and proceeding down
the left-hand side of the logic diagram of FIG. 4a, it is seen that the
crystal input for the internal oscillator of the microcomputer is
connected across the second and third pins of the computer chip. The
microcomputer 28 is initialized by the application of a RESET signal
generated in an RC circuit which communicates with its fourth pin. The
melody conductor 24 transfers the aforementioned stream of melody bits to
the thirty-ninth pin, a testable input (T1). The bit state at this pin
reflects the state of the rightmost location of the shift register 54 of
the melody input latch 20.
The twelfth through nineteenth pins locate an eight-bit data bus which
provides a frequency "divisor" to the alternative output configuration
illustrated in FIG. 6. This bus is not utilized when the output
configuration of FIG. 3 is employed.
Port 1 of the microcomputer 28, a "quasi-bidirectional" port, comprising
the thirty-first, thirty-second and thirty-third pins, is unused in the
present invention.
Port 2 is a second quasi-bidirectional port. Five of the eight components
of port 2, accessed at the twenty-first through twenty-fourth and
thirty-fifth pins of the microcomputer 28, are utilized. The pins
communicate, respectively, with the output latching conductor 96, the
melody input latching conductor 64, the harmony input latching conductor
80, the output conductor 95 and the melody input conductor 24. It may be
noted that the port as utilized is clearly bidirectional, in that it both
accepts data along the conductor 24 and transfers data out of the
microcomputer 28 along the conductor 95.
The eighth and thirty-sixth pins of the chip provide means for
communicating addressing signals to a programmable oscillator chip, the
data input of which is addressed through the pins of the eight-bit data
bus, discussed supra. The data bus forms a significant element of the
alternative output configuration of FIG. 6.
Utilizing the apparatus disclosed in the preceding figures, there is
employed in the present invention a data processing method including
various program steps stored in the internal program ROM of the
microcomputer 28. The program steps, by means of which the system
processes and operates upon keyboard data to generate various control
signals and functions, embody a method for deriving, from the input
harmony and melody data, a number of accompaniment notes harmonious
therewith and for sounding these notes in accordance with a preselected
time dependent sequence so that the resulting sound effects a
predetermined musical playing style.
FIGS. 5(a), 5(b) and 5(c) present flow charts of three embodiments of the
method of the invention. The disclosed embodiments effect the musical
styles known as country piano, strum and accordion (or tremolo),
respectively. Each of the methods illustrated includes teachings disclosed
in co-pending U.S. patent application No. 247,606 of the inventors herein
for "Method and Apparatus for Improved Automatic Harmonization". The
methods of FIGS. 5(a), 5(b) and 5(c) share the teachings of the referenced
patent application insofar as they employ tables of accompaniment notes
wherein appropriate accompaniment notes are arranged and selected
according to the harmonic relationship of the melody and the chord
selected by the performer. To the extent that the three musical styles
employ the teachings of the referenced patent application in like manner,
the steps of the methods of FIGS. 5(a), 5(b) and 5(c) are given identical
notations. In accordance with that application, proper accompaniment notes
are located by a column-addressing technique based upon musical
transposition. In the instance of the country piano style as illustrated
accompaniment notes are selected from duet-type musical tables while the
strum and accordion styles, as discussed below, employ block-type
harmonization utilizing tables of columns of four accompaniment notes
each. In a duet type table, a single accompaniment note is associated with
the melody and, hence, each column of such accompaniment note table
contains a single value identifying one accompaniment note.
Referring now to FIG. 5(a), the computation for effecting the country piano
style is initialized when power is applied to the circuit by application
of a RESET pulse to the fourth pin of the microcomputer 28 from an RC
circuit. At the same time, the value "zero" is entered into a memory
location of the microcomputer 28, which location is designated herein, and
in the methods disclosed in FIGS. 5(b) and 5(c), for reference purposes as
OLD KEY. In step S-2, the harmony data of the lower keyboard latch 22 is
clocked out of the shift registers 68, 70 and applied to the thirty fifth
pin of the microcomputer by the conductor 82. The data of this serial bit
stream is scanned for chord type and root by a method such as that
disclosed in the above-referenced U.S. patent of George R. Hall and Robert
Hall. In this method, playing key pattern representations are stored in a
digital memory at locations having addresses defining corresponding chord
types. A playing key pattern signal identifying the of the keys played by
the performer is then generated and used to locate the corresponding
stored playing key pattern representation. When a match occurs, the chord
type and root are derived by a processor.
After deriving and storing chord information, the microcomputer 28 proceeds
to the processing of melody data. In step S-3, the count of an 8-bit,
downcounting register R-1 is set to zero while the count of register R-4
of the Intel 8048 is set to 44. R-1 will be utilized in the method as
further described to store the location of accompaniment note information
while R-4 acts as a loop or melody note counter, the value of which
indicates the number of notes of the melody keyboard which remain to be
processed for a given execution of the loop.
The loading of data into the upper keyboard registers 46-54 is signalled by
the application of a downgoing latch signal from the microcomputer
(twenty-second pin) along the conductor 64 of the control bus 30. Upon
transmission of such signal, forty four bits of data are loaded in
parallel into the upper keyboard latch 20, the locations of individual
bits therein corresponding to the relative locations of the notes of the
upper keyboard 10.
Entering the computation loops, at step S-5 the state of the bit located in
the rightmost portion of the upper keyboard latch is examined. This
location, in communication with the thirty ninth pin of the microcomputer
through the conductor 24, initially contains information relating to the
melody note C, octave 4 (note number 44). As successive clocking (PROG)
pulses shift the data of latch 20 rightward, notes to the left of the
aforesaid note are sequentially examined.
Assuming the interrogation at step S-5 does not detect the depression of
note C, octave 4, the method proceeds to step S-6 where the value zero is
entered into the accumulating register RA of the microcomputer 28. The
entry of zero into RA signifies a NOT TRUE condition. When it is followed
by an OUTPUT command, the terminal interfacing the twenty fourth pin goes
low. (The "OUTPUT" command additionally toggles the PROG clock function so
that the low state of the twenty fourth pin is then clocked into the
leftmost location of the converter 84 along the conductor 95.)
The register R-1 is decremented in step S-7 and, in step S-8, interrogated
to determine whether its count has reached zero. The initial decrementing
of register R-1 changes its count from zero to two hundred and fifty-six.
Later it will be shown that the count of R-1 is altered by means of the
subroutine SWAPM contained in lines 60 through 75 of the country piano
program listing of Appendix A.
Assuming that no accompaniment bits have yet been entered into R1 by SWAPM
and that R1 has not yet been decremented to zero, the method then proceeds
to step S-9, an OUTPUT instruction which directs the aforementioned
clocking of a low state (i.e., a zero bit) into the converter 84 in
response to the zero value entered into the accumulating register RA at
step S-6. Loop counting register R4 is then decremented at step S-10 (to
the value "43") and interrogated at step S-11. The latter interrogation
determines whether or not all forty-four melody notes have yet been
examined or processed by the microcomputer 28. In the event that the count
of the register R4 has, in fact, reached zero, the hexadecimal 01H is
entered into the register RA, effectuating the latching of the data of the
converters 84-94 and the subsequent "dumping" of the resulting keying
signal into the plurality of AND gates 100.
Assuming that the interrogation at step S-11 is negative, the process
returns to step S-5 and the state of the bit of data which was shifted
into the rightmost location of the melody shift register 54 by the
toggling of a PROG pulse at step S-9 is now examined. Assuming that the
adjacent (forty third) key has been depressed by the performer, the method
now enters the portion of the loop beginning at step S-12 where the
content of register R4 is compared to the value stored at the memory
location OLD KEY. As such value was set to zero at step S-1 and has not
been altered at this point in the program, while the value currently
stored in the downcounting register R4 has been decremented to forty
three, the method proceeds to step S-13 where the value stored at memory
location OLD KEY is changed (from zero) to that of the downcounting
register R4. This assures that, once TIMER, discussed below, has been
initialized, it will not be continually "reset" to zero since the loop
portion containing steps S-13 and S-14 will be bypassed during future
cycles of the loop beginning with step S-2. At step S-14 the RAM of the
microcomputer is addressed at the location containing the software
counting loop denominated TIMER that is thereby initialized to zero. This
portion of the loop (including steps S-12, S-13 and S-14) serves to
initialize TIMER. An identical loop is included in the methods of FIGS.
5(b) and 5(c) as each of the embodiments employs a counting/timing
function as an essential element in achieving a predetermined musical
style.
At step S-15, the value of TIMER is interrogated and compared with VALUE, a
constant stored in program ROM. The determination and inputting of at
least one preselected, constant such as VALUE occurs in each of the
illustrated implementations of playing style according to the invention.
In each style, the particular constant(s) selected function(s) as a note
hold down time and delay that effectively "times" the sequence of selected
accompaniment notes to effect the desired musical playing style.
Accordingly, the appropriate constant(s) is (are) chosen with regard to
the musical effect desired. In all three embodiments, the magnitude of
VALUE or its equivalent(s) is (are) chosen to approximate the number of
times that the entire loop (with the exception of step S-1) is traversed
during a preselected time interval that is related to the corresponding
playing style. In the instance of the country piano style, VALUE is
selected to approximate the appoggiatura hold down time; that is, the
period of time such note is sounded. The inventors have determined that a
typical piece of country music played at about 120 beats per minute should
have an appoggiatura hold time of about 120 milliseconds. Thus, in the
event that, for example, 5 milliseconds are required to traverse the loop,
VALUE should be set to a loop count of twenty four.
TIMER, having been set to a zero count at S-14, is smaller than the
constant VALUE subsequent to the initial detection of a depressed melody
note at step S-5. Thus, the program proceeds to step S-16 where, in
accordance with the country piano style a pointer is generated to the set
of accompaniment note tables designated "APPOGGIATURA NOTE" by means of
the SELECT subroutine. This subroutine, which is contained in the program
listing of Appendix A at lines 181 through 213, generates a pointer that
directs the computer to a set of APPOGGIATURA NOTE tables stored in
program ROM. A similar routine is utilized to generate corresponding
pointers in the methods associated with FIGS. 5(b) and 5(c). While
listings of computer programs for effecting such alternate methods are not
disclosed herein, it will be appreciated by those skilled in the
programming art that those methods are readily achieved by
straight-forward adaptation of the teachings of the program contained in
Appendix A (which may be found in the application file wrapper of this
patent) to the methods described in conjunction with FIGS. 5(b) and 5(c).
APPOGGIATURA NOTE comprises five duet style tables, each of which
corresponds to one of the five chord types which may have been detected at
step S-2. Each of such tables contains, for selected melody notes, an
accompaniment note which is separated by a single scale tone from an
accompaniment note, denoted a sustained note, that is harmonious with the
melody.
As an aside, the SELECT subroutine may alternately produce a pointer
identifying a second set of tables, designated "SUSTAINED NOTE", at step
S-21 when TIMER exceeds VALUE. The SUSTAINED NOTE tables parallel the
ACCOMPANIMENT NOTE tables: five separate duet type harmonization tables,
each of which corresponds to one of the five chord types which may have
been identified at step S-2. Portions of the ACCOMPANIMENT NOTE and
SUSTAINED NOTE tables may be identical for a given detected chord type.
Such a concurrence will be seen to cause the sounding of individual melody
notes without an appoggiatura. Where an appoggiatura is effected, the
corresponding notes of the two tables differ by one scale tone. This is
proper in a musical sense as the repeated sounding of appoggiatura notes
with melody could be considered a monotonous and tiresome musical effect
not representing good country piano style. Thus, the accompaniment notes
from the APPOGGIATURA NOTE and the SUSTAINED NOTE tables, which are paired
and will be seen to be sounded sequentially for a given melody and chord,
are derived so that, in the event that the appoggiatura affect is not
musically proper, no such effect is sounded.
The APPOGGIATURA NOTE and SUSTAINED NOTE tables corresponding to the
detection of a major chord, root C, are listed below:
______________________________________
APPOGGIATURA NOTE TABLE
melody C C.music-sharp.
D D.music-sharp.
E F F.music-sharp.
G G.music-sharp.
A A.music-sharp.
B
accomp. G G G G G C D.music-sharp. D E D E E
SUSTAINED NOTE TABLE
melody C C.music-sharp.
D D.music-sharp.
E F F.music-sharp.
G G.music-sharp.
A A.music-sharp.
B
accomp. G G A G G D D.music-sharp. E E E E E
______________________________________
By comparing the values of the accompaniment notes contained in the
foregoing tables, it is apparent that, when a major chord is played by the
performer, an appoggiatura affect, wherein the two accompaniment notes
differ by a single scale tone, is sounded in accordance with the invention
only when the performer has selected one of melody notes D, F, G, and A.
(The data identifying accompaniment notes is stored in tables of numbers,
each of such numbers representing a tone interval, rather than in the
above-noted form. This renders the tables readily amenable to
transposition in accordance with melody note and chord root as is taught
in the referenced pending application of the inventors.) It is understood
that other musically useful effects can be created by using accompaniment
notes chromatically adjacent to each other or separated by one or more
chromatic tones.
Returning to the flow chart of FIG. 5(a), TIMER is incremented at step S-17
and, at step S-18, the subroutine GET AOC is executed . This subroutine
manipulates data identified by the pointer generated by the SELECT
subroutine at either of steps S-16 (as APPOGIATURA NOTE, contained in the
program listing of Appendix A (not printed herein, but on file with the
U.S. Patent and Trademark Office in the instant application file wrapper)
at lines 228 through 291) or S-21 (as SUSTAINED NOTE, contained in lines
181 through 218).
GET AOC retrieves two bytes, each comprised of two 4-bit nibbles of binary
data. As the duet-type tables utilized in effecting the country piano
style comprise single-valued columns, only the first or right-most nibble
actually identifies an accompaniment note. The latter three nibbles are
each zero-valued. The bytes are arranged in the columns of an appropriate
(APPOGGIATURA NOTE or SUSTAINED NOTE) accompaniment note table arranged
according to and containing information as above-described. The bytes are
stored in two registers (R5 and R6) of the RAM array of the microcomputer
28. The first nibble of each pair of bytes represents the interval from
the last-named note of the table, going down columns, beginning with the
leftmost column. That is, if it were to be determined that the last note
called out by the table were the note G, octave 3, then the number 5 as
the succeeding entry of the table would correspond to the note located
five tones to its left or D, octave 3. The subsequent zeros, which occur
in the processing of duet-type tables, indicate no fi | | |
