Musicians have long admired the clean harmonies produced by the system of tuning known as Just Intonation. Based ultimately on the physics of resonating strings and air columns, Just Intonation achieves the smooth, `beatless' tone blends toward which fine string and vocal ensembles naturally gravitate. On a justly intoned keyboard, the intervals and chords basic to the key to which it has been tuned sound beautifully consonant.
Why then isn't Just Intonation more widely used in keyboard instruments? Because, unfortunately, it has a nasty tendency to make chords not closely related to the tuning key sound sour. According to one authority, in complete Just Intonation only 50% of the major and minor triads are good. The remainder contain many `wolf intervals', so named because somebody once remarked that they sound like the howling of wolves. Many historically important systems of tuning, including the so-called `well-tempered' intonations, were designed as compromises with Just Intonation. They were essentially adjustments allowing for more modulation before the wolf chords are encountered.
The need to accommodate more and more modulation has culminated in our era in the almost universal use of Equal Temperament for keyboard and fretted instruments. Equal Temperament carries the historic well-tempered tuning compromises to their logical extreme. In Equal Temperament all intervals except octaves are slightly out of tune, but the out-of-tuneness is distributed in such a way that music played in one key makes exactly the same tuning compromises as when played in any other key. It is a neat, convenient, and versatile temperament, but it is not necessarily the most musical.
Many older reference works claim that Johann Sebastian Bach invented, or at least favored, Equal Temperament, and composed his renowned `Well Tempered Clavier' to illustrate its use. This claim is now known to be a myth. Equal Temperament had already been discovered in Bach's time, but he and other composers of his era generally preferred not to use it. `Well-tempered' did _not_ mean equal-tempered to Bach. One cannot help wondering how many later keyboard composers might, like Bach, have preferred tuning systems other than Equal Temperament, if only freer modulation could somehow have been accommodated.
The current near-universal adoption of Equal Temperament has been based on the assumption that it is essential for free modulation, there being no practical way to retune a keyboard instrument as the internal harmonies of a piece change. But today's computer-controlled sound modules make this premise obsolete. Tunings can now be changed instantly at the touch of a finger, the tap of a foot, or even automatically when a certain chord is played. That development has already caused a resurgence of interest in tunings. As for the future, some predict tuning revolutions.
The RealTime Tuner is an experimental program created to see what can be accomplished musically when MIDI instruments can be retuned quickly and conveniently as they are played. Instant retuning is the key to making temperaments other than Equal Temperament usable in a contemporary setting. The other temperaments will become practicable to the extent that musicians can easily retune as they modulate.
A tuning program should offer a variety of temperaments. Given free choice, the tuning system selected by a musician could well differ from composition to composition or even vary within a composition. The selection could depend on how far the piece modulates, historic and aesthetic considerations, and so on. The RealTime Tuner offers a menu of just and other intonations, to which further temperaments can be added by the user as desired.
A useful idea that seems to have occurred independently to a number of people is to set aside a portion of the keyboard as a silent `tuning octave'. When the player presses a key in this octave, a signal is sent out to the computer to retune the system to that tonic. In this way the player can make tuning changes that are appropriate to the harmonic changes in the music as they occur.
The notion of a tuning octave can be usefully extended. An octave is commonly thought of as a block of thirteen contiguous keys on the keyboard. For twelve-tone systems, only twelve of the keys in the tuning octave are needed for retuning in response to key changes. It seems natural to make the thirteenth key a means of escaping temporarily from the demands of a system other than Equal Temperament. In the RealTime Tuner program the bottom key of the tuning octave serves as the Equal Temperament escape key.
There are good reasons for having such a key. A player might anticipate that there are complicated passages coming up for which the key is not clearly defined. Better to take refuge in Equal Temperament than to risk sour notes. Or the player might recognize that an upcoming passage is so demanding that during it there will be no opportunity for retuning. Or a conventional equally tempered instrument may be about to join the music, at which point it will become useless to fight the Equal Temperament. Finally, for certain passages a musician might simply like Equal Temperament better. Indeed some musicians prefer Just Intonation for sustained chords but Equal Temperament for naked melody lines. There is no reason why they shouldn't have both.
Some purists might object to such wanton temperament-mixing. Those who feel strongly on the point are of course welcome not to use the escape key. But there is a middle course to consider, namely, to use an escape mode which is not so great a departure from Just Intonation as Equal Temperament would be. Meantone or one of the historic well-temperings might provide sufficient refuge from the wolves. Flexibility in that regard is provided in The RealTime Tuner program by allowing the musician to select any desired temperament as the escape mode.
Moreover, for certain harmonically straightforward kinds of music, the computer itself may be able to recognize the harmonies well enough to help out with the retuning. There need then be no change of temperament at all for the escape mode, only a shift into autotuning. The program includes an automatic chord following facility for exploring this possibility.
Setting aside a keyboard octave for tuning entails the loss of an octave for playing. It may be possible to mitigate the loss by transposing the rest of the keyboard up or down by an octave. But if losing the octave is still unacceptable, a second controller--for example, a small auxiliary keyboard or pedalboard--might be considered for sending the tuning signals. There is also the possibility of a second musician supplying the tunings, either from an auxiliary keyboard or from the computer. Still another possibility is for the performer to use a pedal or foot switch to step through a series of preset tunings, leaving the hands free. The program makes provision for all of these approaches.
A good tuning program should be capable of recording a performance as a MIDI file, tunings and all. In addition, the program should provide convenient ways of adding tunings into a MIDI file created independently with a conventional sequencer. The ability to spot-edit the tunings in an already-tuned MIDI file would also be an asset. The RealTime Tuner offers these recording and editing facilities.
Each of the various tuning conveniences mentioned above could presumably be helpful to some degree. If well-coordinated in a single program, the whole could be worth more than the sum of the parts. How valuable might an integrated ensemble of such aids be? One could speculate endlessly, but instead of theorizing it seems simpler and more to the point just to try the idea out. Hence this experimental program.