Bernstein provides two distinct meanings of the term ambiguity. The first is "doubtful or uncertain" and the second, "capable of being understood in two or more possible senses" (p. 195). In terms of musical ambiguity, Bernstein …
Bernstein provides two distinct meanings of the term ambiguity. The first is "doubtful or uncertain" and the second, "capable of being understood in two or more possible senses" (p. 195). In terms of musical ambiguity, Bernstein discusses ambiguity predominantly in terms of tonality and increasing chromaticism. He traces the use of tonality through Berlioz, Wagner, and Debussy, focusing on the new ways in which composers obscured tonality and how these modifications ultimately affected ambiguity.
In part one of this lecture, Bernstein names three different types of musical ambiguity: (1) phonological ambiguity, or uncertainty of the key, (2) syntactic ambiguity, or uncertainty of meter, and (3) semantic ambiguity, or uncertainty of the meaning. Beethoven's sixth symphony represents a semantic ambiguity, because it could mean either the musical notes performed or the extramusical associations of a pastoral (pp. 199–201).
Finally, Bernstein discusses Berlioz's Roméo et Juliette, paying particular attention to the programmatic element of Berlioz's music (pp. 217–225). He details Berlioz's depiction of the balcony scene, using musical ambiguity to identify extrinsic metaphors, such as the contrast between music depicting the dance and Romeo's "lovesick sighs" (p. 219). The key is another example of ambiguity, because it ambles between two different key areas as Romeo deliberates about a decision (p. 221).
In part 2 of this lecture, Bernstein examines Wagner's Tristan und Isolde in terms of its similarities to and increase of ambiguity from Berlioz's Roméo et Juliette. Wagner's work is a metaphor for Berlioz's for several reasons beyond the choice of similar plots; therefore Bernstein examines three significant transformations within Tristan to show how the work can be viewed as a rewriting of Berlioz's piece. A phonological transformation occurs through increased chromaticism, including ambiguous key areas, ambiguous chords, and chromatic melodies. Next, a syntactic transformation heightens metrical ambiguity through the loss of a pulse and clear rhythmic distinctions (p. 235). Lastly, Tristan's semantic transformation, or "its true semantic quality" is Wagner's strong reliance upon musical metaphor. The piece "is one long series of infinitely slow transformations, metaphor upon metaphor, from the mysterious first phrase through to the climactic heights of passion or of transfiguration, right to the end" (p. 237).
https://en.wikipedia.org/wiki/The_Unanswered_Question_(lecture_series)
