Augmented seventh Augmented seventh In classical music from Western culture, an augmented seventh is an interval produced by widening a major seventh by a chromatic semitone. For instance, the interval from C to B is a major seventh, eleven semitones wide, and both the intervals from C to B, and from C to B are augmented sevenths, spanning twelve semitones. Being augmented, it is classified as a dissonant interval. However, it is enharmonically equivalent to the perfect octave. Since an octave can be described as a major seventh augmented by a diatonic semitone, the augmented seventh is the sum of an octave,
Octave glissando upward with the right hand. The "Alborada del gracioso" from Maurice Ravel's "Miroirs" contains glissandi in thirds and fourths in one hand. Octave glissando An octave glissando is a glissando played on the piano by maintaining a constant distance of an octave between the thumb and finger used to execute it, and shifting the whole hand in the direction of the glissando. Due to the positions of the thumbs on the player's hands, octave glissandos are almost always executed upwards with the left hand and downwards with the right. However, exceptions include Balakirev's "Islamey", where players are instructed to execute