Classification
Lyre from various times and places are regarded by some organologists (specialists in the history of musical instruments) as a branch of the zither family, a general category that includes not only zithers, but many different stringed instruments, such as lutes, guitars, kantele, and psalteries.
Others view the lyre and zither as being two separate classes. Those specialists maintain that the zither is distinguished by strings spread across all or most of its soundboard, or the top surface of its sound chest, also called soundbox or resonator, as opposed to the lyre, whose strings emanate from a more or less common point off the soundboard, such as a tailpiece. Examples of that difference include a piano (a keyed zither) and a violin (referred to by some as a species of fingerboard lyre). Some specialists even argue that instruments such as the violin and guitar belong to a class apart from the lyre because they have no yokes or uprights surmounting their resonators as "true" lyres have. This group they usually refer to as the lute class, after the instrument of that name, and include within it the guitar, the violin, the banjo, and similar stringed instruments with fingerboards. Those who differ with that opinion counter by calling the lute, violin, guitar, banjo, and other such instruments "independent fingerboard lyres," as opposed to simply "fingerboard lyres" such as the Welsh crwth, which have both fingerboards and frameworks above their resonators.
One point on which organologists universally agree is that lyres are closely related to harps (and, in some views, lutes). The other point of agreement is that harps are different from lyres in having strings emanating directly up from the soundboard and residing in a plane that is near perpendicular to the soundboard, as opposed to lyres, lutes, zithers and similar instruments, whose strings are attached to one or more points somewhere off the soundboard (e.g.., wrest pins on a zither, tailpiece on a lyre or lute) and lie in a plane essentially parallel to it. They also agree that neither the overall size of the instrument nor the particular number of strings on it are essential to the classification of these instruments. For example, small Scottish and Irish harps can be held on the lap, while some ancient Sumerian lyres appear to have been as tall as a seated man (see Kinsky; also Sachs, History ..., under "References"). Regarding the number of strings, the standard 88-key piano has many more strings than even the largest harp, and harps have many more strings than lyres.
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