Double flute - dvojačka
Dvojačka (pronounce [dvoyatschka]) is a traditional combination of a 6-hole shepherd's flute with an overtone flute. A player blows simultaneously to both pipes, one of them having a function of a melodic pipe, the other playing a constant drone (usually on the tonic (1), or quint (5)).
I make double flutes in all keys from a small D (flute length 28 cm) to a large D (56 cm). Most popular keys are G and A.
Sound sample: a double flute in E