Chromaticism is a method of composition that uses notes from outside the standard scale for the music’s central tonality. In simple terms, this means that the music contains notes that many listeners may perceive as “sour” rather than harmonious. These notes can be used as a part of a chord or as a melody in their own right. Depending on the type of music being played, chromaticism can be implemented in a variety of ways, and the sour notes can be used sparingly or frequently. These potentially sour notes may sound very pleasing in the hands of a gifted musician due to the context or the way they are used, or they may be used specifically to create an unsettling mood.
In simple terms, scales are recurring note patterns that sound good to the human ear and revolve around a central tonal key. The major scale, for example, has seven notes that are always a certain distance apart, and while the specific notes change as the scale is moved to different keys, the basic pattern in terms of musical distance between each note remains the same. The chromatic scale, on the other hand, is the sequence of all 12 basic notes. On a piano, for example, if someone played any 12 consecutive notes, including both the black and white keys, they would be playing the chromatic scale. For the purposes of this discussion, this means that the chromatic scale contains all of the notes found in other scales, as well as all of the notes in between those notes, which are the tones that sound sour to the average ear.
Chromaticity has been used musicians in various forms throughout history. When a note is bent on a stringed instrument, for example, there is a period where the listener “experiences” the chromatic notes in between the start and end points of the bend. The listener usually accepts this and thinks it’s fine because the musician begins and ends the bend in the correct tonal key, allowing the chromaticism to function as a building of tension that is eventually released in a harmonically comfortable manner. This same effect of sliding fluidly between tonally acceptable notes is a common technique used singers, and it can be found in music to some extent whenever there is vibrato.
When there is a full delineation of the notes rather than a sliding effect, chromaticism is much more pronounced, but musicians are often able to make the notes sound comfortable to the human ear. Most of the time, the musician will play “passing notes,” which are chromatic notes played in between tonally correct notes. Basically, the musician will frequently begin and end any musical phrases on a note that does not sound sour to the listener, giving the impression that the notes in between have been resolved, even if many of them are extremely sour. This is something that many jazz musicians excel at, and it’s also something that many major composers have incorporated, starting with the romantic era and progressing through history.
In some music, the chromaticism’s inherent sourness is embraced, with no attempt to make the sour notes fit or make the listener comfortable. Anyone who has heard the music on a movie score, particularly horror films, has likely heard music that employs this type of chromaticism to create a sense of unease or chaos. Many composers have used chromaticism to push the boundaries of music throughout history, sometimes leading to music with no tonal center at all, which is referred to as “atonal” music.