The 19th Century was a time in which western art music truly began its course through history. Societies were on the uprise, as were technological advances that altered the lives of all citizens. With these rapidly changing times came a drastic advancement in sound. By the turn of the 20th Century, composers began to think outside the box and explore new melodic opportunities that would undermine functional tonality such as the exploration of modal scales and impressionism. These untraditional techniques evoked a new atmosphere for its listeners to experience.
To fully perceive the elegance and innovation of 20th century music, one must first understand its roots. Composers of the 19th century would approach their compositions “vertically”, putting emphasis on each chord and making sure the progression flows with proper voice leading. It was more than common to see a focus on predominant – dominant – tonic chord progressions. This technique allowed the listener to feel a specific, limited range of emotions as the music almost always resolved with grace and simplicity. In contrast to this technique, 20th Century composers such as Igor Stravinsky approached their compositions in a more “horizontal” manner. Stravinsky would include diatonic modes in his music, each proposing its individual sense of “brightness” or “darkness” to his compositions.
Just as artists of the 20th Century began to find freedom in their creative work with the start of modernism, composers left their old traditions behind and found a new freedom of expression. This development in sound was not just harmonic but rhythmic as well. The listener could feel a strong perception of each beat in 19th century music. However, composers of the 20th century would purposefully attempt to hide the beat, creating no clear perception of time, but rather a vast “wall” of sound. Stravinsky played an essential role in this advancement of rhythm by including two or more meters in his music at once or “polymeter”. Not to be confused with polymeter, “polyrhythm” was another popular technique brought to use after the 19th century. This phenomenon happens when two contrasting rhythms occur at once, and could be found in the music of Stravinsky and many more 20th century composers.
Many options arose for composers of the Romantic era when circle-of-fifths progressions such as iii-vi-ii-V-I came to use. This progression still remains exceedingly popular today as its motion through the circle towards the root strengthens the home key while adding momentum to the music. This was also a period in which predominant chords were used to substitute for ii and V, giving composers a new way to escape the tonic and emphasis the pull between V and I. This segued into new concepts of consonance and dissonance when 20th Century composers strayed away from strict harmonic progressions, making it difficult for one to analyze the music in roman numerals. Classic examples of this concept could be found in the music of Béla Bartók, who would often include two simultaneously occurring keys or “bitonality” in his compositions, undermining any trace of functional harmony in a piece.
Often considered the most important figure in 20th Century music, French composer Claude Debussy used extended techniques to disrupt his listener’s perception of tonal harmony. This included the usage of harmonic “planing”, the movement of two or more lines in parallel motion. These said lines would often move diatonically, through different modes, or even at random. Debussy also distorted his listener’s sense of functional harmony by incorporating the whole-tone and chromatic scales into his works. This was a favored technique of his, as its structure bestows a sound of dreaminess and dissolution in the music. Unlike music of the 19th century, Debussy’s compositions do not follow a particular form such as sonata form. Instead, he allows his compositions to develop unpredictably with emancipation of rhythm.
The 20th century was an imperative era in the history of western art music. Keeping in mind all rules of functional harmony from previous eras, composers of the 20th century challenged these rules, taking advantage of their newly discovered rhythmic and tonal freedom. This resulted in emotionally driven music full of satire and ambiguity, and influenced a future full of innovation and creativity.