Vronn (-)
(with) definite article: arNeighbourhood of Carnac; Due to the common mutation of initial consonants in Breton this term can usually be found in dictionaries under Bronn(où) [breast(s)]; "(an) divronn" is a dual, meaning (the) 2 breasts, but it would not be used for blowpipes because they don’t form a pair.
Musique bretonne: histoire des sonneurs de tradition. Douarnenez, 1996, p.332.