The Tristan Chord

Theorists have struggled many decades to explain the first simultaneity of the Prelude to Wagner’s Tristan und Isolde. An interpretation that seems to be widely credited today equates the TC with the enharmonically related half-diminished seventh chord. The difficulty with this notion is that the outer-voice interval of the TC is specifically an augmented ninth, not a minor tenth, and these two intervals differ radically in tonal music, not only in function but in sheer sonority. The TC is explained here as resulting from an enlarged slide formation together with a daring application of elision.