The dulce melos (or doucemelle) is an early keyboard instrument and possible ancestor of the piano. The instrument is described as a type of zither, similar to a hammered dulcimer, but with the strings struck by hammers on keys. The instrument had twelve pairs of strings, each divided into three sections in a 4:2:1 ratio, resulting in a full chromatic octave of 36 notes, as each note is divided into two higher octaves by the bridges. Among the instrument's first attestations was a 1440 work by Henri-Arnault de Zwolle.