with good alternative resonances can produce very low sounds in the hands of skilled players; instruments with four valves can play even lower. The lowest note in the widely known repertoire is a 16 Hz double-pedal C0 in the William Kraft piece Encounters II, which is often played using a timed flutter tongue rather than by buzzing the lips. The fundamental of this pitch borders on infrasound and its overtones define the pitch in the listener's ear. The most convincing explanation for false tones is that the horn is acting as a "third of a pipe" rather than as a half-pipe. The bell remains an anti-node, but there would then be a node one-third of the way back to the mouthpiece. If so, it seems that the fundamental would be missing entirely, and would only be inferred from the overtones. However, the node and the antinode collide in the same spot and cancel out the fundamental. Materials and finish The tuba is generally constructed of brass, which is either unfinished, lacquered or electro-plated with nickel, gold or silver. Unfinished brass will eventually tarnish and thus must be periodically polished to maintain its appearance. Manufacturers There are many types of tubas that are manufactured in Europe, the United States, and Asia. In Europe, the predominant models that are professionally used are Meinl-Weston (Germany) and Miraphone (Germany). Asian brands include the Yamaha Corporation (Japan) and Jupiter Instruments (Taiwan). Holton Instrument Company and King Musical Instruments are some of the most well known brands from the United States. Variations Some tubas are capable of being converted into a marching style, known as "marching tubas". A leadpipe can be manually screwed on next to the valves. The tuba is then usually rested on the left shoulder (although some tubas allow use of the right shoulder), with the bell facing directly in front of the player. Some marching tubas are made only for marching, and cannot be converted into a concert model. Most marching bands opt for the sousaphone, an instrument that is easier to carry since it was invented specifically for this and almost always cheaper than a true marching tuba. The earlier helicon is still used by bands in Europe and other parts of the world. Drum and bugle corps players, however, generally use marching tubas or Contrabass bugles. Standard tubas can also be played whilst standing. With the comfort of the player