Here we have a body of air in a more or less globular body, rather than a column of air in a tube, and its acoustical behaviour is rather different. The pitch depends upon two factors: the volume of the body and the area of open holes, both the hole one blows into and any fingerholes that are opened. The position of any of the fingerholes on the body that are opened is immaterial, all that matters is the total open area, so that the player has considerable flexibility about in which order the holes are opened.
Vessel flutes are either rim-blown across a hole or are duct-blown; I have never seen one notch-blown and transversely-blown are very rare – one example is the Oceanic bamboo nose flute, which is acoustically a vessel flute but is described in this series under ‘Nose Flutes’, because it is held straight out rather than transversely – it is however side-blown which could have brought it here. Of course many modern duct-blown ocarinas are held transversely, but being duct-blown takes priority in description.
Many such instruments around the world are natural objects, often gourds or other emptied seed shells. One early one used in the European late Middle Ages and early Renaissance was a wild-goat horn, called a gemshorn, nowadays more often reproduced with a cow horn; it seems always to have been duct-blown.
They are also made of wood, often with two fingerholes near the embouchure plus a fingerhole in the end, and are used, for example in Africa, by some peoples as signal whistles and others as musical instruments; this dual use of the same instrument is one of the difficulties in dividing whistles from instruments proper.
Others have been made in pottery, again over much of the world, for we have examples from Papua New Guinea with two fingerholes, from pre-Columbian and modern South America with six or more fingerholes, often in a bird or animal shape, from China where the xun, egg-shaped in pottery, had an important ritual role, and from Europe as well as elsewhere. Body shapes are almost infinitely variable. They are also often mass-produced as ‘fairings’ either as souvenirs of a major fair, or as children’s toys.
The best-known of the European ones are, from the nineteenth century onwards, duct-blown in what is called a torpedoe-shape with a duct projecting from one side. These were first invented by Giuseppe Donati of Budrio, developing a toy called the ocarina into a serious musical instrument capable of playing a full scale, using ten or twelve fingerholes. This was not, of course, the first European vessel flute, for at least one has been found in a Neolithic context, and one can , as usual, assume that vegetable forms preceded the pottery ones.
More recently, in the 1960s, John Taylor of London invented the small four-hole vessel flutes capable of playing a full diatonic scale, that have been reproduced for players around the world, often suspended round the neck on a thong.
Acoustically, vessel flutes are blown Helmholtz resonators, and this is the simplest form, with one hole to blow into and another to open or stop – any other further holes are simply the acoustical equivalent of a larger sound hole. They cannot normally be overblown into a higher register, but their fundamental (closed-hole) pitch can be varied by use of a slide to increase the air-volume. Their tuning can be controlled in this way, and extreme chromatics such as microtones are playable by part-covering fingerholes. Normal chromatics are produced most simply by providing fingerholes of differing diameter, although examples with holes all of the same diameter can produced chromatics by part-covering a hole, so reducing its area. The sound is somewhat hollow, due to the lack of overtones and approaches what acousticians call a sine-tone.
© Jeremy Montagu, 2018