From Academic Kids
The ocarina, sometimes called the sweet potato, is a wind instrument. It is made up of an (usually) oval-shaped, enclosed space and four to thirteen finger holes. A mouth tube projects from it, often from the side. One sound hole exists, most often on the underside of the instrument's body. They are made of earthenware, although a few exceptions composed of inexpensive plastics exist.
The ocarina is a very old instrument, believed to date back some 12,000 years. It is of particular importance in Chinese and Mesoamerican cultures (where they are often shaped as animals, many times birds). Its common use in the Western countries dates to the 19th century, when the modern form of the ocarina was invented by Italian Giuseppe Donati. The name is derived from Italian (ocarina 'little goose', for the instrument's resemblance to the head of a bird). The ocarina was believed to be first created when it was discovered that blowing across the mouth of a water vessel or pouring jug that had broken could produce different tonalities when the holes or cracks were (un)covered with the hand or fingers. The Meissen factory in Germany did not make the Ocarina, but allowed local German ocarina-makers to use the Meissen blue and white "onion pattern" as the exterior design.
The ocarina is a vessel flute, not a closed-pipe instrument contrary to common belief, since the sound is created by resonance of the entire cavity (which is not pipe-shaped). This has different acoustical physics from a pipe. Technically, the cavity acts as a Helmholtz resonator (see below).
The ocarina has an unusual quality of not relying on the pipe length to produce a particular tone. Instead the tone is dependent on ratio of the total surface area of opened holes to the total volume enclosed by the instrument. This means that, unlike a flute or recorder, the placement of the holes on an ocarina is largely irrelevant -- their size is the most important factor.
The resonator in the ocarina creates a sine-shaped sound wave and is thus incapable of creating harmonic overtones. This means that the technique of overblowing to get a range of higher pitched notes is not possible with the ocarina, so the range of pitches available is limited.
Different notes are produced by fingering the holes, opening and closing more or less of the total hole area. The tone is then produced through the sound hole. The tone can also be varied by changing the strength with which one blows through the instrument.
Appearance in works
Ocarinas experienced a slight surge in popularity in the last years of the 20th century due to the release of two popular video games for the Nintendo 64, Legend of Zelda: Ocarina of Time in 1998, and Legend of Zelda: Majora's Mask in 2000, in which the hero Link used the instrument to travel through time and magically manipulate his environment.
Another magical ocarina also appears in the fantasy movie Ancanar.
The old fashioned jugband jug has similar properties. A recent instrument, a derivative of the ocarina called a huaca, was invented by Sharon Rowell. The huaca has three separate chambers and can therefore create a polyphonic sound.