Many of the stringed instruments used in Celtic music—including the guitar, mandolin, and bouzouki—are descended from various early incarnations of the lute, and so share a common ancestry. A significant portion of the instruments below became common to playing traditional Celtic music only after the dawn of the sweeping folk revival of the 1960s and 1970s.
As is common with folk instrumentation, new arrangements are written to accompany new instruments entering the instrumental toolkit for a folk genre: In the case of Celtic music, for example, many traditional arrangements originally written centuries ago for the fiddle have been transcribed in recent decades for guitar, mandolin or others of these instruments.
Fiddles and Guitars
Just about anyone who's ever watched a music concert or put a coin in a jukebox probably knows how a guitar and fiddle both look and sound. As an example, the fiddle used in Celtic bands is really no different than the violin in a symphony orchestra. The sole difference is the music being played.
The conventional six-string acoustic guitar popular with folk and pop musicians is the same as the guitar employed in Celtic music. Celtic music may also feature some of the modern guitar’s more antique but highly related variants, the English guitar and the guittar (yes, that’s the correct spelling!).
Particularly in Ireland, harpers have historically enjoyed lofty regard for their talents. Since the days of Henry VIII, the harp has served as the symbol of the Irish, appearing on everything from bottles of Guinness to the coin of the realm.
Today’s Gaelic harps are not the immense floorstanding models played in classical orchestras; instead, they are compact, lever-operated and strung with nylon, gut, or wire. As is the case with many Celtic instruments, harps go by a variety of names. Other names in common use include Irish harp, cruit, folk harp, triple harp (a Welsh variety with three rows of strings), cláirseach or clàrsach.
Bouzoukis and Citterns
The modern cittern is a hybrid of several ancestors, including the Portuguese guitarra, the octave mandolin and mandocello. The cittern hit its height of public recognition in the Renaissance, but goes through up-and-down cycles of popularity. Today’s cittern has a teardrop shape, and a flat or gently curved back. Citterns generally have five pairs (or courses) of strings, while a four-course variant is usually referred to as an Irish bouzouki.
The dulcimer originated in the Middle East, but made its way to England in the fourteenth century. The hammered dulcimer resembles a zither or autoharp in appearance, and a harp in sound. The hammered dulcimer has a metal-strung trapezoid-shaped board; players strike the strings with light hammers.
The mandolin is a perennially popular instrument in any kind of folk style, including Celtic, and has two relatives, the mandola and the mandocello (the latter also known as an octave mandolin). The mandolin has a rounded back and four pairs of strings, tuned like a fiddle. By contrast, the larger mandola and mandocello are tuned a fifth below and an octave below, respectively. The mandocello closely resembles the Irish bouzouki in most respects.