An augmented fourth, augmented sixth, and augmented ninth above the root make up the Tristan chord. Although other composers used this chord, it is most famously associated with Richard Wagner, who used it in the first bars of his opera “Tristan und Isolde” with the pitches F, B, D#, and G#. The chord is a part of Tristan’s theme or leitmotif and is one of the most well-known chords in the world of music. The pitches could be respelled to make a standard half diminished seventh chord, but the chord’s relationship to the rest of the piece in “Tristan und Isolde” is unique.
Because theorists disagree on how to analyze the Tristan chord, it is one of the most hotly debated chords in music theory. Both functional and nonfunctional theory approaches have been used to examine it. Different interpretations of the chord exist within each of these approaches, none of which can be proven to be correct or incorrect.
The fact that some of the notes can be interpreted as appoggiaturas is crucial to understanding the Tristan chord — and the crux of the analysis debate. An embellishing note, or one that comes before a pitch that is more important to the melody, is known as an appoggiatura. In other words, some chord notes may be left out of the analysis, resulting in a significant change in how the chord functions.
Despite the fact that there are numerous interpretations of the Tristan chord, Wagner chose one by Czech professor K. Mayrberger, who analyzed the chord on the second degree (II) and treated the G# as an appoggiatura. This chord was split in Mayrberger’s opinion. The F seemed to correspond to the key of A minor, while the D# seemed to correspond to the key of E minor.
Many theorists saw the chord’s duality, as seen by Mayrberger, as foreshadowing the abandonment of traditional harmony in favor of approaches such as polytonality. Polytonality refers to a composer’s use of multiple keys at the same time. Musicians hailed the Tristan chord as the pinnacle of contemporary harmony, but it is actually found in a lot of tonal music, including Ludwig Von Beethoven’s, Johann Sebastian Bach’s, and Wolfgang Amadeus Mozart’s. As a result, modern theorists frequently see the chord as Wagner’s contemporary adaptation of harmony.
The Tristan chord is so well-known that it has been parodied or borrowed by many composers, despite the fact that it appears in a few different spellings. Some of these parodies and borrowings are deliberate homages to Wagner, while others aren’t. This is significant because, in most cases, it is melody that is borrowed. The specific sound created by harmonic intervals is what composers latch on to and purposefully replicate within various genres with the Tristan chord.