The crumhorn is a capped reed instrument. Its construction is similar to that of the chanter of a bagpipes. A double reed is mounted inside a chamber at one end of a long pipe. Blowing into the chamber produces a musical note. The pitch of the note can be varied by opening or closing finger holes along the length of the pipe. One unusual feature of the crumhorn is its shape; the end is bent upwards in a curve, so that the instrument resembles a banana, or more prosaically, the letter J.
Crumhorns sound something like a trumpet, something like an oboe and somthing like a duck. They have a limited range, usually an octave and one note, because it is not possible to get the reed to overblow at higher harmonics, since the reed is not held in the mouth. As a result, music for crumhorns is usually played by a group of instruments of different sizes and hence at different pitches. Such a group is known as a consort of crumhorns.