Organistrum
Medieval hurdy-gurdy.
What it means
The organistrum is a large medieval form of the hurdy-gurdy. In this type of instrument, a wheel prepared with rosin and turned by a crank continuously bows the strings; keys or rods shorten the melody string, while further strings ring on as a drone. The organistrum is so large that it was operated by two people: one turned the crank, the other operated the keys. It is depicted above all in the architectural sculpture of the High Middle Ages; no original instruments survive, which is why reconstructions rest on pictorial sources.
Musical use
The instrument belongs in the context of medieval music-making with drone sound: over a constant fundamental a melody moves, and the harmony arises from the friction between them. Because the wheel holds the note for any length of time, the sound resembles a bowed instrument more than a plucked one. From the organistrum, smaller hurdy-gurdies playable by one person developed, which remain alive to this day in the folk-music traditions of several countries. Information on tuning, number of keys, and use is uncertain and not uniform in scholarship.
Performance practice
The wheel must be turned evenly, for every irregularity is audible as a volume fluctuation; the crank hand works calmly and in an even circle. The wheel is treated regularly with rosin and must run clean and round, otherwise the tone rustles or wobbles. Moisture considerably changes the grip. With two-handed reconstructions, the coordination between crank and keyboard is the actual task: entries and articulation must be agreed upon. Tune the drone strings to the stock of notes of the respective piece, since a change during play is not possible.
Bear in mind that the sound depends entirely on the wheel: an unevenly running or unevenly coated wheel produces fluctuations that cannot be played away. Check it before every performance and apply rosin sparingly and evenly. The humidity of the room noticeably changes the grip; reckon with this and plan a warm-up time.