Over a large area of south-western Bulgaria, songs are mostly two-part. The first voice sings the melody; the second voice is smooth or slightly more florid, mostly on the tonic and adjacent degrees of the scale. This area can be divided into four regions, differentiated by the styles of singing in two-part songs: Pirina region, the region to the centre of western Bulgaria, and the Velingrad and Ihktiman Pazardjik regions. Each of these regions shows a different structure of two-part songs. The differences lie in harmonic and rhythmic structure, and in the range of the second voice.

The most widespread style is that of the Pirina region, characterized by the comparative restriction of the second voice.

Typical of the Velingrad region are the songs with a vigorously moving second part, ranging mainly between the first, third and fourth degrees of the scale and the leading note. Typical of the Ikhtiman region (the smallest of the four) are two-part songs with an elaborately ornamented second part woven round the melody and reaching the tonic a little before the first voice.