Pitch Processing
The Continuum Fingerboard has a pitch system that employs two concepts. The first is the idea that any section of the left to right Surface Position of the Continuum can be mapped to any pitch, and the second is that these pitch references can be initially or subsequently rounded to a Rounding Grid.
Surface Position
A section of the Continuum top surface. The pitch Surface Position has been marked with yellow numbers.
Pitch Values
When a finger is placed is placed on the Continuum, its pitch position is constantly calculated and can be expressed as the value of the pitch number for the associated surface position number. The fractional part of this number is the deviation from a standard Midi note pitch.
Pitch Values
Three fingers in contact with the Continuum surface. Each finger is numerically represented in white by the value of the blue pitch in relation to the yellow surface position. In this case (and in most other cases) these blue pitch numbers and yellow surface position numbers have a one-to-one relationship.
Playing the Continuum
The Continuum Fingerboard requires precise finger positioning techniques.  Continuous pitch provides amazing new expressive possibilities for a musician, but requires a great deal of practice to play in tune, especially polyphonically. You must precisely place fingers for an in-tune performance. Not only must each finger be placed in the exact position at the beginning of each note; each finger must be in exact position after you perform glissandi and other finger movements.  Finger positions must be accurate to a fraction of a millimeter (3 to 5 cents) to sound in tune. To aid the player with this positioning, there are Note Markings on the playing surface, and the ability to use a Rounding Grid.
Note Markings
To aid the player in playing to an equal tempered reference, the Continuum can have patterned playing surface. This can be either either silk screened or laser etched. Both types of surfaces have markings which represent a 12 division octave.
Note Markings
Note markings along with equivalent musical note names and surface position numbers on the Silk Screened Continuum surface.
Note markings along with equivalent musical note names and surface position numbers on the Laser Etched Continuum surface.
The Rounding Grid
The Continuum Fingerboard includes a sophisticated mechanism to correct finger positions.  It allows you to place fingers with positional errors, and still hear a note (or a chord, if you are playing polyphonically) that corresponds to perfectly placed fingers.  You may then slide your fingers (glissando) to new positions; the notes will glide in pitch to the new finger positions, and then they will be corrected. When finger positions are corrected, we refer to this as “rounding the finger position”.  Finger position may be corrected when the finger first touches the surface (Round Initial), and after the finger slides on the surface (Round Rate).The Round Rate mechanism works in such a way as to not diminish the expressive possibilities of subtle pitch changes like vibrato (periodic variation in pitch), grace notes (small glissandi) or large pitch sweeps.  For instance, if a note is played with vibrato, small adjustments will be made so that the averaged finger position (and the perceived pitch) is precisely correct.
Round Rate
The Round Rate can be specified in two ways:
(1)  The Round Rate pedal (controller 5 on channel 16) can be used to change the Round Rate during a performance.  A Round Rate of 0 means no rounding; small Round Rates cause a slow drift to grid positions; larger rates round more quickly. The maximum Round Rate of 127 causes immediate rounding; with this rate you will get a piano-style glissando when you slide a finger over adjacent grid positions.
(2)  In the absence of controller 5, the Default Round Rate is used. You can configure the Default Round Rate with Midi In (see the section on Midi configuration), or from the playing surface (see the section on Overlay Strips.)
The Rounding Grid
Precisely correct pitches correspond to certain finger positions.  These fixed positions form a grid; the grid may be spaced evenly (as in equal-tempered tuning) or unevenly (for example as used by Just Intonation tunings). Esoteric and downright bizarre tunings and grids can be user specified. The Round Rate mechanism also allows you to control the rate at which finger position correction drifts toward the rounding grid, anywhere from instantaneous to glacial.
Pitch Position and Rounding Grid Choices
Equal Tempered Grid
In this standard tuning there is an even relationship between surface location and pitch position, and all rounding points are equally spaced.
Equal Tempered Tuning
The fingers in contact with the Continuum surface are mapped to a standard pitch reference (in yellow). If Rounding is activated then the finger pitches will be rounded to an equal tempered grid (shown in blue). The first note changes from 66.582 to 67 (G), the second to 68 (G#), and the third to 71 (B).
Just Tuned Rounding Grid
A preset Just tuning scale is available on the Continuum, in twelve tonic centers. In this standard tuning there is an even relationship between location and pitch, but all rounding positions are not equally spaced, reflecting the numerical variances from a standard equal tempered 12 division octave.
In this Just tuning, any of the major triads (I, IV, V) will have perfect 4:5:6 frequency ratios in the rounded finger position, and the ii and vi minor triads will have perfect 10:12:15 frequency ratios. You can change the tonic key for the tuning at any time, even while fingers are pressing on the Continuum Fingerboard’s playing surface; the Round Rate mechanism will correct the positions of those fingers to the new tuning.
Just Tuned C Scale
The fingers in contact with the Continuum surface are being rounded to a Just C Scale grid. The blue pitch points are the same values as the yellow surface positions, thereby preserving the linear progression of pitch values.
Division of the Octave into "N" Parts Grid
In this alternate tuning there is an even relationship between location and pitch, and all rounding positions are equally spaced, reflecting the division of each octave into "N" equal parts.
The normal octave can be divided into anywhere from 1 to 50 equal parts. For instance quarter tone music would use a division of 24.
Ten Note Octave
The fingers in contact with the Continuum surface are being rounded to a 10 note octave grid. The blue pitch points are the same values as the yellow surface positions, thereby preserving the linear progression of pitch values.
Custom Tuning Grids
The Continuum Fingerboard has 8 user-definable downloadable tuning grids. The grid points in a tuning are used for Round Initial Pitches, for Round Rate, and for nonuniform pitch-warping of the playing surface without any rounding. Each grid point is defined by two numbers: a position on the surface (specified by equal tempered note number with fractional value, shown in yellow), and the pitch for that position (specified by note number with fractional value, shown in blue). For most tunings, the pitch matches the position at each grid point; if not, the number of cents per inch will vary across the surface. These tuning grids can be created by sending NRPN values to the Continuum as described in the Configuration page, or by using on online Tuning Downloader web application.
Custom Tuning Grid Examples
Below are three examples of possible tuning grids. In each example only about one octave of surface position values are shown. For these examples it is assumed that the pattern of the surface to pitch mapping will continue above and below the surface ranges shown. In reality, this does not have to the case. All three examples could be combined into one custom tuning grid, each example in a different Continuum surface position area.
Example 1 - Stretched Note Spacing
An example of using the pitch processing of the Continuum for something other than rounding purposes. The fingers in contact with the Continuum surface are playing on a stretched tuned surface, so that four octaves of playing surface in yellow is equivalent to one octave of pitch change in blue. This type of tuning would be useful in exploring microtonal pitch clusters, where adjacent notes need to be something less than a semitone apart. Note that with rounding engaged pitches would resolve at the rounding rate to an equal tempered tuning grid. In this example the lower two notes will resolve with rounding to the same tuning grid value, 62.
Example 2 - Reversed Whole Tone
The fingers in contact with the Continuum surface will be playing reversed blue pitches, centered around middle C (60). As well, the grid spacing is in whole tones (2 semitones), so that if rounding is engaged notes will round to the nearest whole step grid point.
Example 3 - F# Major Just Triads
The fingers in contact with the Continuum surface are being rounded to a Just Tuned scale with an F# tonic center, however only major triad points (F#, A#, C#) are being used. All notes will round to one of these values in each octave.