11 - Improvisation

Question 1

Improvisation

Answer 1

• composition occurs simultaneously with performance

- can be contrasted with 1) composition and 2) performance

Question 2

Improvised forms in the arts

Answer 2

• improvised music forms
• contact improvisation (dance)
• devised theatre
• improv acting

Question 3

Structure of improvisation

Answer 3

• guided improvisation
• constrained by features of the style
• limited by physical constraints
• based on patterns, formals, or motor routines

Question 4

Approaches to empirically study improvisation

Answer 4

• experimental manipulation
• correlational analysis with non-improv skills
• corpus analysis
• interview analyses
• ethnographic analyses

Question 5

Theories of improvisation

Answer 5

• Pressing (patterns) = pre-learned patterns, motor routines, formulas
• Johnson-Laird (procedures) = musical rules and their application

Question 6

Ways to progress in an improvisation

Answer 6

• associative transitions = musical improvisers may concatenate melodic figures based on a repository of pre-learned patterns; moves along the same thread (typical)
• interruptive transitions = new thread of musical figures (sudden change)

Question 7

Entropy

Answer 7

• measure of the absence of structure, order, or predictability in a system
• the higher the entropy, the less structured, organized, or predictable a system is
• represents musical diversity

Question 8

Conditional entropy

Answer 8

• measuring the diversity of transitions between pitch classes
• a higher conditional entropy means a higher variety of pitch-class transitions (i.e. less predictable transitions)

Question 9

Types of constraints in improvisation

Answer 9

• cognitive

- music-theoretic

Question 10

Goldman - Study

Answer 10

• jazz musicians
• improvise over a backing track
• improvisations were pooled by factor

Question 11

Goldman - IVs

Answer 11

• within-subject (2 x 2 x 2)
• key = B-flat (familiari), B (unfamiliar)
• hand = right, left
• function = melody, bass

Question 12

Goldman - DVs

Answer 12

• entropy of the pitch classes
• conditional entropy of the pitch classes
• diatonic proportion (Major key diatonic pitches/total pitches)

Question 13

Goldman - Main Results

Answer 13

• entropy = main effect of key; higher entropy in familiar key
• conditional entropy = main effect of hand and function; right had higher than left, melody had higher than bass
• diatonic proportion = main effect of key; unfamiliar key had higher diatonic
• interactions = 2-way interaction between key and function for diatonic proportion; key had a greater effect on the melody line than bass

Question 14

Norgaard - Study

Answer 14

• analyzed 48 of Charlie Parker’s solos
• corpus from a transcribed collection (low error rate)
• control corpora = random, computer-generated

Question 15

Norgaard - Procedure

Answer 15

• pairs of pitches converted into directional intervals (size and contour)
• pattern = sequence had to occur twice or more in the corpus
• can not include = long rests, note values longer than 4 beats
• each note considered a possible start point

Question 16

Norgaard - Notation

Answer 16

• perforated brackets = pattern repeated in the corpus, but only once in the solo
• solid brackets = repeated in corpus and solo; number in the bracket = times in the solo

Question 17

Norgaard - Main Results

Answer 17

• 99.3% of all of the notes in the corpus were parts of patterns consisting of 3 or more intervals that occurred two or more times
• 82.6% of the eligible notes in the corpus began a 4-interval pattern that occurred two times
• the value was 57.6% if rhythm was included in the definition of a pattern
• 5-interval patterns had the highest number of unique patterns
• the mean length of interval patterns was 7.3 intervals after eliminating overlapping patterns
• the longest interval pattern was a 49-interval pattern that occurred twice, both times in the same solo
• the longest patterns occurred uniquely in single solos, but most mid-length patterns (15-29 intervals) occurred in multiple solos