Characteristics of Jazz

        The melody of jazz is normally instrumental rather than vocal.  Because of the presence of wide melodic leaps, jazz is many times not considered to be “singable.”  However, some melodies can be sung with the use of scats, where the voice is used to mirror the sound of an instrument using nonsense syllables, in the place of words. Call-and-response patterns are widely used in jazz music, and riffs (short, repeated phrases) are typical of a jazz melody.  Blue notes are created by lowering the 3^rd and 7^th steps of a major scale and often the 5^th as well.  The melody of typical jazz compositions consists of mostly improvisation.  Usually only one instrument improvises at a time.  Because of the strong emphasis on improvisation, the melody is seldom heard.  For instance, if a jazz song lasts about ten minutes, only two of those minutes would have the original melody playing, which is often called the “theme” or “head.”  
         Jazz musicians base their improvisation off of the song’s harmonic chord progression rather than the melody.  Harmony serves as the foundation of a performance and is commonly the only aspect, aside from the “theme” played at the beginning and end, prearranged prior to performance.  Jazz harmony “uses all the stops” as some might say because it takes advantage of chords with five or even six notes to create a full, rich harmony distinct from any other.  The harmony can either be tonal or modal depending on the particular piece.  The progression is traditionally twelve measures long and is broken into three phrases of four measures based on the standard progression of I, IV, and V chords although ii-V-I is also common.  In a ii-V-I chord progression, this analysis would almost never be the entire chord progression but rather a small section of it characterized by the roots of the chords moving up by fourths and down by fifths.  These chords do not always stick to the analysis of course because they are subject to the artist’s use of improvisation.  Vamps, short repeating sequences of chords, are also at the disposal of the performer. 
          In jazz rhythm since the Swing Era, the accents fall either on the off-beats or in between beats utilizing a technique known as syncopation; this is commonly referred to as “four-beat rhythm.”  In a 4/4 time signature, the natural accents would be on the first and third beat (ONE two THREE four), but syncopation places the accents in opposite locations (one TWO three FOUR).  “Two-beat rhythm” was practiced prior to “four-beat rhythm” and had a bassists or drummer play on the natural accents while a pianist or guitarist played chords on the off-beats. 
          Altering instruments was second nature to jazz performers.  Jazz musicians didn’t want to be locked down to one timbre which their instrument could produce, so they took matters into their own hands.  Trumpet or trombone players would use mutes to suppress its tone, and wind players would operate their instrument in a different manner in order to yield results like vibrato, shakes, bent pitches, falls, splats, and growls.  Pianists would grab the strings of the piano plucking them to gain the desired effect. 
          The medium of jazz music consists of two categories: melody instruments, which obviously control the melody and thus the improvisation, and chordal instruments, which accompany the melody and supply the chords.  The melodic instruments are typically the trombone, trumpet, saxophone, clarinet, flute, tuba, and violin and play the “theme” of the piece; likewise, the chordal instruments are the piano, organ, vibraphone or marimba, drums, guitar, and banjo.