The adjustment, generally made before a musical performance, of the intervals or the overall pitch level of an instrument. Inflections of pitch that form an inherent part of the performance itself are usually thought of as a matter of intonation (see Intonation (ii)) rather than tuning. The term is also commonly used to refer to the note or (more often) the set of notes or intervals to which a particular instrument is tuned. The tunings, in this sense, of individual instruments are discussed in the articles on the instruments concerned (see also Re-entrant tuning). A third use of the term is in the sense of the ‘tuning system’ employed, referring to a model of the scale corresponding to some mathematical division of the octave. For the history of such models in performing practice, see Temperaments, Well-tempered clavier, Mean-tone, Just intonation and Pythagorean intonation.
Wind instruments in an ensemble are tuned to make their general pitch level uniform by adjusting the length of tubing in each instrument. Tuning-slides are shifted in brass instruments, the top joint in a flute, the staple of the reed in an oboe, etc. The extent to which bass reed instruments can be tuned is slight, as each millimetre of difference amounts to a smaller portion of the total tube length than on a treble instrument. On the other hand, the palpable lengthening or shortening of any woodwind instrument will complicate the player’s task during performance by tending to put the instrument slightly out of tune with itself: to sound a precise octave above the new basic pitch, for instance, the player must compensate for the fact that the effective tube length provided by the normal fingering is no longer precisely half the overall length. The techniques used for this compensation are likely to affect timbre, volume or articulation. Hence the intonation and voicing of a good woodwind instrument are displayed best when it is at the pitch level intended by the maker; this is especially true of the oboe, the instrument which provides the a' to which the orchestra tunes (this pitch being used because the violas and cellos as well as the violins have a string tuned to A, and this is the cello’s highest and hence clearest string). That pitch level itself, however, varies somewhat with temperature, gradually rising as the instrument is warmed by the player’s breath.
On string instruments the tuner adjusts the tension and sometimes the sounding length of the string. Gross alterations of tension are avoided because of the danger of breakage and because a pronounced change in the stress borne by the instrument will more or less subtly alter its shape and hence in turn the sounding length, tension and pitch of any previously tuned strings. (At least two tunings are thus required to raise or lower the pitch level of a piano, the first being unlikely to leave the instrument very well in tune.)
Most keyboard instruments have so many strings or pipes that some of them are far more suitable to begin a tuning with than others. The octave around middle C on the keyboard, perhaps f–f', is traditional nowadays on the organ (using pipes of the 4' Principal rank) and on the piano (using the middle of the three strings for each note, the other two being dampened by a strip of felt which the tuner inserts). One note, for example a or c', is set to a pitch standard from a tuning-fork or the like, and then the rest of the octave is tuned through a network of consonant intervals extending from this starting-point. Often a chain of 5ths and 4ths is used (for instance A–D–G–C etc), but many tuners use 3rds and major 6ths at least as much (see Equal temperament). Once the initial octave has been set, the tuning is extended to the other octaves and, finally, to the other sets of strings or pipes.
In judging intervals a tuner listens, consciously or subliminally, for beats among the overtones of the two notes involved. Hence differences in timbre crucially affect the procedure. It would be difficult to set precisely tempered intervals by a stopped-flute rank on the organ, for example, because its timbre is weak in the odd-numbered members of the harmonic overtone series. In piano timbre a mild degree of inharmonicity obliges the tuner to make all the octaves slightly larger than the theoretical norm of 1200 cents (which would be an octave with a frequency ratio of exactly 2:1). While the proper amount varies with the particular instrument, a general indication is given in Table 1 (based on suggestions made by the Tuners Supply Co. of Boston, Massachusetts). Some of the ‘stretch’ in the extreme bass and treble, however, is for the sake of a certain melodic bite gained by making the octaves larger than harmonic justness would dictate. In this respect different tuners and musicians have different tastes, but markedly stretched octaves are at best a mixed blessing in chamber music, where a more sober intonation will allow the non-keyboard instruments to blend more resonantly.
On instruments with extremely inharmonic timbre, the criteria for good tuning are quite different. Each Indonesian gamelan, for example, is likely to have its own shading of the pelog or slendro scale, and these shadings differ far more than the various temperaments of the Western tradition. Yet within each gamelan the unisons and octaves are tuned precisely to achieve certain qualities of beating and, according to Hood (Selected Reports, 1966), definite patterns of stretching or compressing the octaves for certain notes of the pelog or slendro scale. See also Bell (i).
For bibliography see Temperaments and Intonation (ii).
MARK LINDLEY