The modern hammered dulcimer is a trapezoidal-shaped instrument with 24 to 30 courses of treble and bass strings with a partially chromatic range from D[inf 3] to D[inf 6], which is played with light wooden hammers. The treble strings are divided by a middle bridge in a ratio of 2:3 so that each course provides two notes a musical fifth apart. Although acoustically similar to the piano, the distinctly different bridge/soundboard placement and hammer/string interactions give the hammered dulcimer a unique percussive sound. Historically in the United States, the hammered dulcimer has remained almost exclusively a folk instrument, most often used as a lead or rhythm instrument in traditional dance bands, but more recently as a concert instrument as well. Instrument builders, almost exclusively folk craft people, and players themselves, have responded with new designs that have changed the sound characteristics and musical and physical flexibility of the instrument.