Implied polyphony in the unaccompanied string works of J. S. Bach: Analysis, perception, and performance

Performers, pedagogues, and theorists agree that Bach created a sense of counterpoint in his unaccompanied string works by outlining multiple voices within a single instrumental line. Little attempt is made, however, to discuss the specific musical features that create this impression of counterpoint or to provide guidelines for determining what these different voices actually are. In response to this lack of adequate research, a concrete system for parsing these monophonic lines into multiple voices was developed and a taxonomy of implied polyphony types was created.;Experimental methods were then used to determine how implied polyphony affects various perceived characteristics of these pieces. The basic hypothesis was that Bach used the technique of implied polyphony to create an expressive surface, something that would interrupt the regularities inherent in monophonic, isochronous melodies. Statistical analysis of the results confirmed that passages with implied polyphony are indeed considered more engaging. The results also suggest that all types of implied polyphony do not behave in the same manner, with the perceived aesthetic quality only being affected when the implied polyphony significantly changes basic melodic patterns or motives.;These findings were then applied to a detailed analysis of the relationship between implied polyphony and other structural aspects of this music---in particular, grouping structure and metric structure. Although implied polyphony can serve to shift or obscure grouping boundaries, this research suggests that its main function is to preserve one of the basic attributes of Baroque meter. Bach's use of implied polyphony essentially applied irregular accent patterns to the surface of this music, thus creating purposeful and engaging activity at the fastest levels of the metric hierarchy.;Finally, this research begins to inform the study of the expressive performance of these pieces. Commercial recordings were examined to determine how performers use tempo rubato to communicate this contrapuntal structure. Although performers are often given the vague suggestion to "bring out the counterpoint", this initial data suggests that the opposite approach could also be taken. Performers who realize that passages with implied polyphony contain a certain amount of "structural expression" have the freedom to let this feature emerge on its own or to provide added emphasis through the use of rubato and other expressive techniques.