Adjective
bisonoric (not comparable)
(music) In an accordion: producing a different note when the bellows are compressed or expanded.
His instrument also could sound two different chords with the same key; one for each bellows direction (a bisonoric action). Source: Internet
They are generally bisonoric, use a different style of "long plate" reeds, and tend to be square rather than hexagonal. citation Unlike the English and Anglo, they sometimes have more than one reed per note, creating a vibrato effect. Source: Internet
While the right hand is bisonoric, the left hand follows the Stradella system. Source: Internet