A neutral second is a musical interval half-way between a minor second and a major second. It is thus a quarter tone sharp from the minor and a quarter tone flat from the major and is found in the quarter tone scale and Arab music and tuning. In music theory, an interval is the difference (a ratio or logarithmic measure) in pitch between two notes and often refers to those two notes themselves (otherwise known as a dyad). ... The musical interval of a half step, semitone, or minor second is the relationship between the leading tone and the first note (the root or tonic) in a major scale. ... The musical interval of a major second — also called a whole-tone — is the relationship between the first note (the root or tonic) and the second note in a major scale (and also a minor scale). ... A quarter tone is an interval half as wide (aurally, or logarithmically) as a semitone, which is half a whole tone. ... Arab music is the music of Arabic-speaking people or countries, especially those centered around the Arabian Peninsula, though Peter van der Merwe (1989, p. ... The modern Arab tone system, or system of musical tuning, is based upon the theoretical division of the octave into twenty-four equal divisions or 24-tone equal temperament, the distance between each successive note being a quarter tone (50 cents). ...