In jazz and blues, a blue note (also "worried" note) is a note sung or played at a slightly lower pitch than that of the major scale for expressive purposes. Typically the alteration is a semitone or less, but this varies among performers and genres. Country blues, in particular, features wide variations from the diatonic pitches with emotive blue-notes. Blue notes are often seen as akin to relative pitches found in traditional African work songs.

The blue notes are usually said to be the flattened third, flattened fifth, and flattened seventh scale degrees. Though the blues scale has "an inherent minor tonality, it is commonly 'forced' over major-key chord changes, resulting in a distinctively dissonant conflict of tonalities". A similar conflict occurs between the notes of the minor scale and the minor blues scale, as heard in songs such as "Why Don't You Do Right?."

In the case of the flattened third over the root (or the flattened seventh over the dominant), the resulting chord is a neutral mixed third chord.

John Scofield (born December 26, 1951, Dayton, Ohio), often referred to as "Sco," is an American jazz guitarist and composer, who has played and collaborated with Miles Davis, Dave Liebman, Joe Henderson, Charles Mingus, Joey Defrancesco, Herbie Hancock, Pat Metheny, Bill Frisell, Pat Martino, Mavis Staples, Phil Lesh, Billy Cobham, Medeski Martin & Wood, George Duke, Jaco Pastorius, John Mayer, and many other well-known artists. At ease in the bebop idiom, Scofield is also well versed in jazz fusion, funk, blues, soul, and other forms of modern American music.

Early in his life, Scofield's family left Ohio and relocated to the small, then mostly rural location of Wilton, Connecticut; it was here that he discovered his interest in music.

Educated at the Berklee College of Music, Scofield eventually left school to record with Chet Baker and Gerry Mulligan. He joined the Billy Cobham/George Duke Band soon after and spent two years playing, recording and touring with them. Scofield recorded with Charles Mingus in 1976, and replaced Pat Metheny in Gary Burton's quartet. In autumn 1976 he signed a contract with Enja Records, and he released his first album, John Scofield, in 1977. Around this time, he toured and recorded with Pianist Hal Galper, first on his own solo album Rough House in 1978, and Galper's album Ivory Forest (1980), where he is heard playing a solo rendition of Thelonious Monk's "Monk's Mood". In 1979 he formed a trio with his mentor Steve Swallow and Adam Nussbaum which, with drummer Bill Stewart replacing Nussbaum, has become the signature group of Scofield's career. In 1982, he joined Miles Davis, with whom he remained for three and a half years. He contributed tunes and guitar work to three Davis recordings, Star People, You're under Arrest and Decoy.

Eric Johnson (born August 17, 1954) is an American musician, songwriter, and vocalist from Austin, Texas. Best known for his electric guitar skills, Johnson is also a highly proficient acoustic, lap steel, resonator, and bass guitarist as well as an accomplished pianist and vocalist.

Johnson has mastered a wide array of musical genres evidenced by the many different styles incorporated in both his studio and live performances including rock, blues, jazz, fusion, soul, folk, New Age, classical, and country and western.

Guitar Player magazine has called Johnson "one of the most respected guitarists on the planet". Johnson's stylistic diversity and technical proficiency with the guitar have been praised by Bill Hicks. His 1990 platinum-selling, full-length album, Ah Via Musicom, produced the single, "Cliffs Of Dover", for which Johnson won the 1991 Grammy Award for Best Rock Instrumental Performance.

Born into a musically-inclined family, Johnson and his three sisters studied piano and his father was a whistling enthusiast. Johnson started learning the guitar at age 11 and rapidly began progressing through the music that would heavily influence his future style, including Eric Clapton, Mike Bloomfield, Chet Atkins, Cream, Jimi Hendrix, Wes Montgomery, Jerry Reed, Bob Dylan and Django Reinhardt, among others. At the age of 15, he joined his first professional band—Mariani, a psychedelic rock group. In 1968, Johnson and the group recorded a demo, which saw extremely limited release; years later the recording became a prized collector's item.

Mike Stern (born Mike Sedgwick on January 10, 1953) is an American jazz guitarist. After playing for a few years with Blood, Sweat & Tears, he landed a gig with drummer Billy Cobham and then broke through with trumpeter Miles Davis' comeback band from 1981 to 1983, and again in 1985. Following that he launched a solo career, releasing more than a dozen albums. He was hailed as the Best Jazz Guitarist of 1993 by Guitar Player magazine, and in 2009 was listed on Down Beat's list of 75 best jazz guitar players.

Stern was born Mike Sedgwick in Boston, Massachusetts, the son of Helen Burroughs and Henry Dwight Sedgwick V. He is the half-brother of actress Kyra Sedgwick; his full sister, Holly, is the mother of actor Philip Nozuka and singers George Nozuka, Justin Nozuka, and Henry Nozuka. Stern is married to guitarist and vocalist Leni Stern.

At the Berklee College of Music in Boston his focus shifted to jazz. Stern landed a gig with Blood, Sweat & Tears in 1976 and remained with the band for two years, appearing on the BS&T albums More Than Ever and Brand New Day.

Herbert Jeffrey "Herbie" Hancock (born April 12, 1940) is an American pianist, keyboardist, bandleader and composer. As part of Miles Davis's Second Great Quintet, Hancock helped to redefine the role of a jazz rhythm section and was one of the primary architects of the "post-bop" sound. He was one of the first jazz musicians to embrace music synthesizers and funk music (characterized by syncopated drum beats). Hancock's music is often melodic and accessible; he has had many songs "cross over" and achieved success among pop audiences. His music embraces elements of funk and soul while adopting freer stylistic elements from jazz. In his jazz improvisation, he possesses a unique creative blend of jazz, blues, and modern classical music, with harmonic stylings much like the styles of Claude Debussy and Maurice Ravel.

Hancock's best-known solo works include "Cantaloupe Island", "Watermelon Man" (later performed by dozens of musicians, including bandleader Mongo Santamaría), "Maiden Voyage", "Chameleon", and the singles "I Thought It Was You" and "Rockit". His 2007 tribute album River: The Joni Letters won the 2008 Grammy Award for Album of the Year, only the second jazz album ever to win the award after Getz/Gilberto in 1965.