Bulgarian singing is an ancient tradition that still continues. The music is traditionally sung by women. Vocal sounds that are characteristic of Bulgarian singing are ululations, nasalized tone quality (originally developed so that women could project their voices across fields), and flips – rapid ascents and descents from a notated pitch (usually the interval of a minor third). The music is based on the drone principle: singers are divided so that one sings the melody, and two or more sing a second part that functions as a drone.

Dve Nevesti is a characteristic example of a Bulgarian song. It is antiphonal (two groups of singers answer one another in alternation) and in a diaphonic (two-voice) mode. Voices are in a close frequency range of each other. A spectrogram of the drone part of the fist phrase of the song (second voice) indicates how each phoneme of the text gives the phrase a definitive shape. The noise bands created by [s] can be seen in the high end of the frequency spectrum. The phrase begins in mid-range with the vowel [ei] moving to [i] and down again to [o]. (Fig.2) In this spectrogram the phonemes are recognizable as sound segments consisting of vowels and consonants. The phoneme boundaries are distinct, and are blurred only in the transition from [sti] to [or], where the high formant area of [i] descends to [o].
Fig. 2 Dve Nevesti, first phrase (drone part)