Studies in psycho-linguistics have provided compelling evidence that theoretical syntactic structures have cognitive correlates that inform and influence language perception. Generative grammar models also present a principled way to represent a plethora of hierarchical structures outside the domain of language. Hierarchical aspects of musical structure, in particular, are often described through grammar models. Whether such models carry perceptual relevance in music, however, in unclear.

We utilised the formalism developed in Rohrmeier (2020) and its implementation developed in Harasim, Finkensiep, Ericson, O’Donnell  & Rohrmeier (2020) to design a new paradigm testing the perceptual reality behind hierarchical harmonic structure in music.  Specifically, participants listened to short musical phrases which were stopped earlier, and were then asked to predict how many more chords they expected to come until the phrase could be complete. An example of this is shown in Figure 1.

Figure 1: Example stimulus. Participants did not hear the completion, but instead had to guess how many more chords were to come.

This is analogous to hearing an interrupted sentence, e.g., ‘I like pizza and…’, and being asked how many more words are needed before the sentence can be over. 

Data from 150 participants showed that a hierarchical syntax model added incremental predictive power over a sequential model when it came to predicting participants completion responses. This finding suggests that hierarchical structures are not only an elegant description of musical structure, but also carry relevance to the human cognition and perception of music.

Paper Abstract

Studies in psycho-linguistics have provided compelling evidence that theoretical syntactic structures have cognitive cor-relates that inform and influence language perception. Generative grammar models also present a principled way to represent a plethora of hierarchical structures outside the domain of language. Hierarchical aspects of musical structure, in particular, are often described through grammar models. Whether such models carry perceptual relevance in music, however, requires further study. To address the descriptive adequacy of a gram-mar model in music, unfamiliar musical phrases consisting of chord progressions within the Jazz idiom were used, and zero to three chords were cut from the end of each phrase. A total of 150 participants were then presented with these stimuli and asked to provide aClosure Response, that is to predict how many more chords (0, 1, 2, or 3) were expected before the chord progression was complete. Simultaneously, a grammar model of hierarchical structure as well as a bigram model were trained over a corpus of 150 expert-annotated Jazz tunes. The models were then used to estimate probability distributions ofClosure Responses in the stimuli presented to the participants.Bayesian mixed-effects models reveal that the models carry predictive value for the participants’ response distributions and that the hierarchical model contains incremental predictive in-formation over the bigram model. The present results suggest that – akin to language – hierarchical relationships between musical events have a cognitive correlate, which influences the perception and interpretation of music.

Keywords: Syntactic models; music perception; cognition; tree models; hierarchical structures

Herff, S. A., Harasim, D., Cecchetti, G., Finkensiep, C., & Rohrmeier, M. A. (2021). Hierarchical syntactic structure predicts listeners’ sequence completion in music. In Proceedings of the Annual Meeting of the Cognitive Science Society (Vol. 43).