I recently discovered the Serpent. This is a musical instrument vaguely similar to a tuba, but developed in the late 16th century for the purposes of church music. The idea was apparently to create an instrument which sounds similar to a low male voice, so as to enhance the lower ranges of plainsong. Opinions on the instrument are mixed, to put it tactfully:
It is blown with a cup shaped mouthpiece which is very similar to that of a trombone or Euphonium/Baritone. Played softly, it has a firm yet mellow tone color, or timbre. At medium volume, it produces a robust sound which seems to be a cross between the tuba, the bassoon, and the French horn. When played loudly it can produce unpleasant noises reminiscent of large animals in distress. [source]
The Serpent really requires a totally unique approach and playing technique….Because it is not possible for the basic Serpent to be vented properly, the instrument does not conveniently resonate at the desired pitches the way modern wind instruments do….
Since the Serpent does not center accurately on most notes, the player must be able to ‘sight sing’ the music much like a singer must look at a given note and produce the correct pitch without mechanical assistance. Once the player has the specified pitch in mind, he must then produce the required vibration with his lips, forcing the instrument to go along even if it cannot actually resonate at that frequency.
There must, somewhere, be groups of people dedicated to playing the oddest of instruments. Ideally together.