Articulation is effected by the tongue stopping and opening this windway. However, the lack of direct control of the reed of a windcapped instrument renders these higher notes extremely difficult of access. Thus the normal range is limited to the simple fundamental sounds produced by successive opening of the lateral holes giving an octave and one note. On some modern reconstructions additional keys are provided to extend the range upwards by one or two notes. And there is some evidence to suggest that crumhorns were played without the windcap, possibly to facilitate the production of higher notes.
Crumhorns have a characteristically sharp attack which is very effective in an ensemble.
Depending on how their reeds are voiced, they range in tone from a gentle, somewhat nasal humming to a rich, resonant buzzing. The curve is decorative only, perhaps being a reminder of earlier wind instruments made out of cow's horns, but perhaps to make the long pipe less clumsy for the player. The curved bell section of many surviving instruments is hollowed out to form a more or less conical foot, which has the effect of raising the volume. When the reed is blown through, it vibrates, causing a standing wave to develop in the bore of the crumhorn. Pitch is governed not only by the length of the pipe down to the open finger holes, but also by breath pressure, so that the crumhorns have to be played at a fixed dynamic level.