Ordinarily we suppose that an accompaniment to a melody—in folk music as in art music—is provided by a groundwork which is harmonic or rhythmic, or both. This basis holds together the whole of the melody, either by underlining the harmonic (or rhythmic) idea which lies more or less hidden in the melody itself, or by creating the harmonic (or rhythmic) idea, if the melody itself moves in a very free manner.

In some more highly developed styles of folk music, as well as in those of art music, we find this groundwork strengthened and intensified by the heterogeneous sound of a special instrument which stays more or less in the background. The most outstanding example of what I mean is the well known Gipsy band of southeastern Europe with the sounding background of the cimbalom (dulcimer). A similar principle can be seen in the harpsichord of the Baroque orchestra.