The Structure, Perception and Generation of Musical Patterns

1. Three Experiments • Primary Objectives: • Tie a generative decision - a musical pattern - to some measure of the composer’s perceptions • Influence of perceptions and constraints on generative process • Strategy • Preferences • Similarity The Structure, Perception and Generation of Musical Patterns Nyssim Lefford Sonic Studio, Interactive Institute How do musical creators perceive structure in the patterns they create as they generate them? (focusing predominantly on rhythm)

2. Composition Games: • Well-bounded: Constraints and Goals • Comparable Results • - Different responses to the same game • Responses to games with varying constraints • Previously used in Design Research (Habraken and Gross) • Simple, sparse and rhythmic music games • Get at the fundamentals of the generative process Subject Population in all experiments:Subjects all play and instrument or sing. They varied inage, gender, musical education and experience, instrument, and genre preference.

3. Results: • Patterns varied • Similar strategies for describing structure • External • Internal • Experiments 2 and 3: • Preference and Similarity • Do creators share similar ways of perceiving structure? Experiment 1: • Subjects make simple, rhythmic patterns • click and drag sound samples • numbered boxes without notation or waveform • limited duration of silence • Objectives: • Learn to design games and select meaningful constraints • Will similar constraints yield similar patterns? Similar strategies?

4. time Preference and Similarity The “Nine” Rhythms Baseline: perceptual tests to assess the population and contrast to the patterns generated

5. Consequence 3 Consequence 7 Consequence 5 Antecedent 1 Preference Baseline Test • Poor Predictors:age, gender, education and experience, instrument, genre preference • Trends in results: • Some pairs preferred by a significant percentage • Groups who preferred one pair and also disliked other pairs Preference is highly variable …

6. Similar? Rate 0 … 10 Patterns 4, 5 and 6 Patterns 1, 2 and 3 Patterns 7, 8 and 9 Pattern 1 Pattern 2 Similarity Baseline Test Results: Multidimensional Scaling Subject 1 • First two attacks • Regularity and density

7. Type I Type III Type II Similarity Baseline Results Style 2 Style 1 Found: Three different styles of perceiving of similarity Poor Predictors:age, gender, education and experience, instrument, genre preference Style 3

8. Pattern 1 Pattern 2 Pattern 3 Pattern 4 Pattern 5 Pattern 6 Pattern 7 Pattern 8 Pattern 9 Experiment 2: Make an Antecedent Game • Make an Antecedent then Rank consequences • Preference and Context Nine Consequences First make the antecedent Then rank the consequences • Make the least preferred consequence sound best

9. Subject 2 antecedent consequence antecedent consequence •• - • - - • - • - - • - • - • • - - •• - - • • - - ••• - - •• - - •• - - •• - - •• - - Most Preferred Consequences • - • - •• - - • - • - •• - - •• - - • - • - •• - - • - - • • - • - • - • - •• - - • - • - •• - - • - - • • - - ••• - - • - • - • - - • • - • - • - • - Least Preferred Consequences • - - •• - • - • - • - • - - • • - - •• - - • • - - •• - • - Preference Ranked Pairs • Representation of preferences in context • But results not yet tied to baseline results • Experiment 3…

10. Pattern 1 Pattern 8 Pattern 2 Pattern 9 Pattern 8 Pattern 7 Pattern 4 Pattern 2 Pattern 3 Pattern 4 Pattern 5 Pattern 6 Pattern 9 Pattern 2 Pattern 5 Pattern 1 Pattern 6 Experiment 3: Chaining Game (10 subjects) similar Task: Created a chain using 4 of the 9 rhythms Could use a rhythm more than once 4 pairs of chains Each chain in the pair started with a different rhythm but were perceived as similar Pairs: regular, irregular, dense and sparse Phrases or rhythmic groupings

11. Pattern 9 Pattern 5 Pattern 3 Pattern 8 Analysis of Experiment 3 • Chains plotted on MDS plots • Similar ways of crossing similarity space • Patterns coupled to similarity perceptions

12. Repetitive eg. 9898 Asymmetrical eg. 6278 Circular eg. 9179 Chains: • Out of 80 chains: • 41 Asymmetrical chains • 27 Repetitive chains • 12 Circular chains • New Phrase Groupings: • 39 Two phrases • 10 Three phrases • 15 Four phrases • 16 other • Similarity baseline/MDS plots (poor predictor) • High-level criterion for structuring chains

13. Conclusions Goals: Understanding how the creator perceives structure • What did we learn from the experiments? • Compared creator’s perception of similarity to the patterns they created • 3 Styles of perceiving similarity • Tracked individual creators’ preferences as they generated patterns • a representation of a generative decision mapped to similarity • Future work • Add musical dimensions • Beyond preference and similarity • More complex games

14. Acknowledgements This research was conducted at the Media Lab at the Massachusetts Institute of Technology The Structure, Perception and Generation of Musical Patterns Nyssim Lefford Sonic Studio, Interactive Institute nyssim.lefford@tii.se