the US. A typical concert band trombone section consists of two tenor trombones and one bass trombone, but using multiple players per part is common practice, especially in public-school settings. Use in jazz In the 1900s the trombone assisted the bass or tuba player's job of outlining chords for the other instruments by playing a bass line for the higher-pitched instruments to improvise over. It was not until the swing era of the mid-1920s that the trombone began to be used as a solo instrument. Examples of early trombone soloists are Jack Teagarden and J.J. Johnson. 20th-century construction Changes in construction have occurred during the 20th century, such as the use of different materials; increases in mouthpiece, bore, and bell dimensions; and in types of mutes and valves. Despite the universal switch to a larger horn, many European trombone makers prefer a slightly smaller bore than their American counterparts. One of the most significant changes is the popularity of the F-attachment trigger. Through the mid-20th century, orchestral trombonists used instruments that lacked a trigger because there was no need for one. But as 20th century composers such as Mahler became popular, tenor trombone parts began to extend down into lower ranges that required a trigger. Although some trombonists prefer "straight" trombone models without triggers, most have added them for convenience and versatility. Contemporary use The trombone can be found in symphony orchestras, concert bands, big bands, marching bands, military bands, brass bands, and brass choirs. In chamber music, it is used in brass quintets, quartets, or trios, or trombone trios, quartets, or choirs. The size of a trombone choir can vary from five or six to twenty or more members. Trombones are also common in swing, jazz, merengue, salsa, R&B, ska, and New Orleans brass bands. Construction The trombone is a predominantly cylindrical tube with two "U"-shaped bends and a flared bell at the end. The tubing is approximately cylindrical but actually contains a complex series of tapers which affect the intonation of the instrument. As with other brass instruments, sound is produced by blowing air through pursed lips producing a vibration that creates a standing wave in the instrument. The detachable cup-shaped mouthpiece is similar to that of the baritone horn and closely related to that of the trumpet. It has a venturi: a small constriction of the air column that adds resistance, greatly affecting the tone of the