The Major Eleventh Chord extends the Major Ninth Chord by adding a perfect eleventh. The theoretical notes are: root, major third, perfect fifth, major seventh, major ninth, and perfect eleventh. However, the perfect eleventh forms a semitone interval with the major third, creating a strong and unpleasant dissonance that is almost always avoided in a Maj11 chord. For this reason, the eleventh is almost always altered to an augmented eleventh (#11); in this case, the chord is often called 'Lydian Chord' or 'Maj7#11' (which also implies the ninth, Maj9#11). Alternatively, the third is omitted to accommodate the natural eleventh, although this solution is less common. A 'natural' Maj11 (with the third and natural eleventh) is extremely rare and, if used, requires extremely careful voice leading to avoid sounding 'muddy' or excessively dissonant. The sound of the Maj7#11 (with the augmented eleventh) is bright, ethereal, and 'Lydian', often associated with modern jazz, film scores, and fusion music for its dreamy and open quality.