Implied Polyphony in the Solo String Works of J. S. Bach: A Case for the Perceptual Relevance of Structural Expression

Bach created a sense of counterpoint in his unaccompanied string works by outlining multiple voices within a single instrumental line. In order to better understand the construction and function of this implied polyphony, an analytical system was developed that provides guidelines for determining where transitions between implied voices occur. Two experiments then investigated how implied polyphony affects the perceived aesthetic quality of these pieces. The hypothesis was that Bach used implied polyphony to create “structural expression,” something that would enhance the melody’s appeal without the aid of performer expressivity. Statistical analysis of the results confirmed that passages containing implied polyphony are indeed considered more engaging than those that were recomposed to diminish the sense of counterpoint. Results also suggest, however, that all instances of implied polyphony do not have the same perceptual effect. Listener’s judgments of engagingness were significantly affected when the implied polyphony created simultaneous, linear streams, but not when it created a sense of successive grouping structure.