​SOUNDHOLES, or f-HOLES, two curvilinear openings in the belly of a stringed instrument, one on each side of the bridge. They are popularly supposed to let out the sound; but they are in fact indispensable to its production. But for the soundholes the belly of the fiddle would remain stiff and motionless under the bow. By cutting the soundholes on each side, the thick central section of the belly, extending from the top to the bottom block, and fortified by the bar, is liberated in the middle, and vibrates readily under the bow. It communicates its vibration to the rest of the instrument, and musical tone is the result. It is obvious that the vibration of the central section must be considerably affected by the place, size, and shape of the soundholes: and their true place and size, like that of the bridge, was first determined by the makers of Cremona about the end of the 17th century. Their shape is considerably older.

Fig. 2 shows the development of the soundhole from its primitive form. The primitive soundhole was round, like that of the guitar, Fig. 1 (from a painting in the Florence gallery). Experiment soon proved that it was better to leave the central section entire from top to bottom, and to cut out only the lateral edges of the circle on each side, crescentwise (Fig. 2). The circular soundhole was thus transformed into a pair of crescents, turned face to face; and this continued to be the normal form of soundholes in the 14th and 15th centuries. Fig. 3, a tenor viol from a picture by Montagna in the Accademia, Milan, is a late specimen. The expedient of placing them back to back (Fig. 4) is as old as the middle of the 14th century. This design eventually prevailed for the viol in the 16th century, and remained the distinctive mark of the viol tribe as long as viols continued to be made. (Fig. 4 is from a large Viola da Gamba, by Henry Key of Southwark 1611.) It was used for the Viola da Gamba in England as late as the middle of the last century, and in France somewhat later. It still survives in the hurdy-gurdy. [See Hurdy-Gurdy, vol. i. p. 758.]

The modern soundhole with a contrary flexure was developed from the crescent soundhole by reversing the lower half of the figure (see Fig. 2). In some early instruments these were placed back to back (Fig. 5, from tenor viols in the carved choir-screens of Cremona Cathedral, early in the 16th century). But experiment soon showed the expediency of placing them front to front (Fig. 6, from a very early Italian violin, about 1580), and the soundhole thus attained the familiar shape which is distinctive of the violin tribe. The makers of the 17th century slightly improved the outline. Fig. 7 shows the fiddle soundholes of Stradivari, and their position with reference to the corners. Stradivari first used the fiddle soundhole for his viols, rejecting the crescent shape, and in this he was followed by the other Italian makers.

​One other form of soundhole requires notice. It is called by fiddle-makers the 'flaming sword' (Fig. 8): and as the crescent remained the characteristic of the viola da gamba, the 'flaming sword' remained the characteristic of the viola d'amore, long after the f-soundhole had come into general use. Fig. 9, from an old English viola d'amore (about 1740), shows the flaming sword with the terminations of the ordinary f-hole. Sometimes the flaming-sword termination is used at the top and the ordinary termination at the bottom. This mixed form was generally used for the Barytone (see the engraving in that article), and for the Lyra-Viol, though the tenor Lyra-Viol engraved in the article Lyre has fiddle soundholes.

The rudimentary form of the 'flaming sword' soundhole may be seen in Raffaelle's St. Cecilia in the Bologna Gallery (Fig. 10). It may be described as a 'flame' rather than a 'flaming sword,' and is evidently borrowed from the 'tongue of fire' of the Italian painters. The flaming sword harmonises well with the outline of the viola d'amore, and its shape conduces to a diminished vibration, which the peculiar stringing of the instrument demands.

The f-shaped soundhole has long been used for instruments of all sizes, from the kit to the double-bass, its size being proportionally altered with the scale of the instrument. It is found to produce the maximum of musical vibration, and it is therefore improbable that it will ever be altered in its main features. Uniform as soundholes may appear, they are in fact susceptible of infinite variety in detail, and in their setting in the instrument: and one glance at them is often enough to discover the maker. Different classes of makers generally leaned to a particular form of soundhole. The Germans have made the ugliest. Up to the end of the 17th century there was considerable variety in cutting it: but most makers since Stradivari have copied his soundhole, which is purely geometrical. Those of the Amatis, of Joseph Guarnerius, and of Stainer, are equally familiar. The soundhole is a conspicuous feature in the physiognomy of the instrument. Many old fiddles have been spoiled by having their soundholes recut by unscrupulous vendors, so as to pass for other than they are. So gross a fraud is easily detected, and can therefore only impose on the inexperienced.—The soundholes are traced on the belly by means of one carefully-made pattern (Fig. 11), which is reversed for the second hole; they are then cut ​through with a fine knife, before the belly is glued on. The inner edges are sloped away, but the outer are left sharp. A couple of nicks, exactly half-way, serve to indicate the position of the bridge between the soundholes.^[1]