MUSIC stringed instrument Encyclopædia Britannica Article The production of sound The ear, because of its own structure, adds to and subtracts from the outside sound. It is, for instance, relatively insensitive to low-frequency sound pressure but is extremely sensitive to fine degrees of pitch change. At the same time it can accept a great number of pitch and tuning systems. On a worldwide basis, there is a large and varied number of tonal systems. The oldest known of these in the West is the so-called Pythagorean system; others include mean-tone tuning, just intonation, and the even-tempered system, methods of tuning calculation that vary slightly in the exact size they assign to the intervals within an octave. All of these systems represent theoretical mathematical concepts to some degree, and their origins must be sought in arcane numerological systems rather than in practical musicianship. Thus, “tuning” and “playing in tune” do not necessarily refer to the same thing; players and tuners make constant adjustments to any basic mathematically determined framework according to their judgment and experience. In other words, even though a given “scientific” tuning system outlines scales and modes, the instrumentalist who plays an instrument with great pitch flexibility (the violin, for instance) spends much time in the spaces between the notes assigned in the given scale. The Japanese zither (koto), for example, can be tuned according to a number of fixed systems; nevertheless, its player produces many microtonal variations on these fixed pitches by manipulation of the strings. Even in such a technological society as that of the modern West, the well-tempered scale is honoured more in the breach than in the observance: a piano tuner would not think of tuning altogether according to its dictates and uses a so-called stretched tuning, in which he imperceptibly sharpens (raises) pitches as he ascends, thus making the highest notes relatively sharper than the lowest ones. Investigation has disclosed that string players tend to play in the Pythagorean rather than the well-tempered system. Inconsistencies, then, are inherent in all tuning systems; makers of fretted lutes (the guitar or the Greek lute, laghouta, for example) operate according to a combination of ear and rule of thumb when they insert frets (note-position markers—e.g., of gut or wire) in the fingerboard. Such instruments are fretted according to the “rule of the eighteenth,” in which the first fret is placed at one-eighteenth of the distance from the top to the bottom of the string, the second, one-eighteenth of the distance from the first fret to the bottom, and so on. Even if this method produced an acoustically perfect scale (which it does not), the player would not be able to reproduce this exactly, for as he presses the string to the fingerboard, the string is stretched and is thus slightly lengthened. That is why the act of stopping a string at its exact centre gives a note slightly sharper than the expected octave above the open string. Despite all of this, the search for an acoustically perfect tuning system goes on. Though constructional methods differ widely from one area and instrument to another, there are a limited number of basic problems to be overcome by the maker of stringed instruments. The very principle that makes it possible for chordophones to sound is string tension; at the same time, tension is destructive to the instrument since it tends literally to pull it apart. So the body of an instrument must be made of strong material; it must be reinforced, and at the same time it must not be so rigid that it cannot easily resonate—i.e., produce a supplementary vibration intensifying that of the string. The challenge of reconciling these opposite needs is the central one for the chordophone maker. Climate, too, has a marked effect on musical instruments: humidity expands a wooden instrument, and dryness contracts it. Of these factors, dryness is the most harmful, since the contraction of the wood actually pulls the instrument apart. Much energy has been expended over the centuries in investigations of various varnishes, shellacs, glues, and sealers. Many makers prefer to make their instruments in dry conditions, for the expansion caused by humidity is unlikely to prove as harmful as the contraction caused by dryness.