Before beginning to describe jazz in the twenties, I'd like to tell you about a unique phenomenon in the development of this music. At the beginning of the twentieth century the advent of the Edison Cylinder and later the flat 78 rpm phonograph record made the jazz phenomenon possible. In 1917, jazz became the first musical art form to document it's birth through the process of recording, and the group responsible for this occasion was the ORIGINAL DIXIELAND "JASS" BAND (ODJB).

Reguardless of the circumstances surrounding the first recordings of jazz music, by the early 1920s jazz was ready to take center stage as an internationally recognized music, and as had been in the case in earlier decades, it was the vocalist who dominated the spotlight.

Probably the most unusual reason for the popularity and success of jazz and blues singers was the record label's devotion to the production of race records during the 1920's. Race records were subsidiary labels for the major recording companies, and were introduced after the release of Crazy Blues by Mamie Smith, a black blues singer of the '20's. She sold thousands of copies in the black ghettos of Northern industrial cities like New York, Detroit and Chicago. Almost immediately a talent search began. The goal was to find new blues talent as well as to locate some of the older rural blues artists. These singers, and the New Orleans style jazz bands (also discovered during the search) were brought to Chicago and New York to record material for these new labels.

The style known as "rural blues" flourished in the South during the first two decades of the twentieth century but became much more popular after race recordings appeared in the '20's. Dominated by men, this style is probably the oldest form of blues singing we know about.

Out of the efforts to secure talent for the newly formed race record labels of the '20's, there came the recordings known as the "classic blues." Usually performed by women, this style of blues seemed much more sophisticated than it's forerunner the rural blues sung by Mississippi Delta and North Texas Panhandle males.
For one thing, classic blues singers usually recorded and performed with jazz rhythm sections backing them. Call and response - which in rural performances usually took place between the male singer and his guitar - took place between female vocalists and their top instrumental jazz player. This meant that the quality of the exchanges were quite high, as can be evidenced by listening to trumpeters such as Louis Armstrong or Jow Smith, clarinetist Sidney Bechet or trombonist Jack Teagarden as they performed back up roles on recordings. The subject matter of the classic blues was often concerned with the black urban point of view and the lifestyle of the '20's. The rural style of previous decades was considered old. At this point, the unique background and influence of Louis Armstrong, as both jazz trumpeter and vocalist made an astonishing contribution to jazz as an art. Armstrong brought his clear, mature understanding and familiarity with the instrumental style of melodic statement into his singing with an ease that no one else could begin to match. The results of his early efforts changed jazz vocals forever.
As Louis Armstrong demonstrated scat singing during the 1920s, jazz shifted from being a music most directly influenced by the human voice to one in which instrumental performances were viewed as a tool to be used with skill. It was no longer acceptable to simply blast away at every tune. Likewise, tone and pitch modifiers became the stock and trade of every good player as musicians sought to give themselves a competitive edge. For these reasons, the '20's produced a decade incredibly rich in tone colors. Trumpet and trombone players played with mutes stuck in the ends of their horns, with plungers, with hats or hands placed over the bells of their instruments.
Clarinet players sought to increase their value on the market by "doubling" on other instruments - and the instrument of choice was the saxophone. At the beginning of the decade, jazz bands generally featured only clarinet, while by the middle of the decade bands in Chicago often had two reed players (A reed is a primitive wind instrument made of a hollow reed stalk) with one musician performing on clarinet and the other on alto or tenor sax. By the end of the decade the saxophone actually replaced the clarinet as the preferred instrument for playing jazz.
In the rhythm section, banjo players played 4-string tenor banjo, ukelele and mandolin. Drummers used everything from washboards, thimbles to wood blocks. It was a decade in which the tuba, stand up acoustic bass and washtub bass all served as the bottom of the rhythm section at one time or another, depending on whether the musicians performed purely instrumental jazz or as a back-up band to rural blues singers. Country folk instruments like the harmonica, violin, jews harp and comb-and-tissue paper also had brief periods in the limelight.
Pianists played using stride left-hand techniques often learned by imitating the written music of ragtime. This was particularly useful for playing the non-blues based popular music of the era. Blues piano, soon to be called boogie-woogie, was being recorded by the mid-1920s. Guitarists also tended to learn by imitating and frequently performed in either a chordal style with single-string fills when playing the blues, or in the more difficult rag-guitar style which created an "ohm-pah" sound similar to the stride left-hand of the pianist.