comparative analysis of multiple musical performances
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Comparative analysis of multiple musical performances. Paper by Craig Stuart Sapp 2007 & 2008 Presented by Salehe Erfanian Ebadi QMUL ELE021/ELED021/ELEM021 5 March 2012. Outline. A technique for comparing numerous performances of an identical selection of music - PowerPoint PPT PresentationTRANSCRIPT
Comparative analysis of multiple musical performances
Paper by Craig Stuart Sapp2007 & 2008
Presented by Salehe Erfanian Ebadi
QMUL ELE021/ELED021/ELEM0215 March 2012
OutlineA technique for comparing numerous performances of an
identical selection of musicThe basic methodology is to split a one-dimensional
sequence into all possible sequential sub-sequences, perform some operation on these sequences, and then display a summary of the results as a two-dimensional plot
The current focus is on beat-level information for tempo and dynamics as well as commixtures of the two
MethodologyThe primary operation used on each sub-sequence is
correlation between a reference performance and analogous
The result is a useful navigational aid for coping with large numbers of performances of the same piece of music and for searching for possible influence between performances. segments of other performances
Collected over 2,500 recorded performances for 49 of Chopin’s mazurkas—on average over 50 performances for each mazurka
Some points about performancesKeeping track of differences and similarities between
performances is difficultA written score contains only the most basic of expressive
instructions (The unwritten rules of a composition are transmitted aurally between performers)
So to help exploring influences between performances tempo and dynamics are extracted from each, and then correlated against each other
Each performance in a plot is assigned a color
Raw DataBeat duration & Loudness (easier to extract) using Sonic
VisualizerMany other facets (note timings, voicing, articulation, …)
are ignored
Raw DataFor comparisons of musical dynamics between
performances, a smoothed version of the raw power calculated for the audio signal every 10 ms is sampled at each beat location
Loudness detection uses the smoothed data, with a delay of 70 ms because smoothing introduces a delay in data
Analysis ToolsNormalized (Pearson) Correlation
Values range from −1.0 to +1.0, with 1.0 being an exact match, and 0.0 indicating no predictable relation between the sequences being compared
Analysis ToolsScape PlotsCorrelation values are hard to interpret in isolationOriginally designed for timbral and harmony structural
analysis
Comparative performance scapesChoose one performance to be the reference for a
particular plotFor each cell in the scape plot, measure the correlation
between the reference performance and all other performances, then make note of the performance which yields the highest correlation value
Color the cell with a unique hue assigned to that highest-correlating performance
Timescapes
Timescapes
Dynascapes
Scape plots and parallel feature sequences
HYBRID NUMERIC/RANK SIMILARITY METRICS FOR MUSICAL PERFORMANCE
ANALYSIS
OutlineComparing numerical method for examining similarities
among tempo and loudness to Pearson CorrelationOther concepts such as “noise-floor” are used to
generate more refined measurements than the correlation alone
The measurements are evaluated and compared to plain correlation in their ability to identify performances of the same Chopin mazurka played by the same pianist out of a collection of recordings by various pianists
DataAlmost 3,000 recordings of Chopin mazurkas were
collected to analyze the stylistic evolution of piano playing over the past 100 years of recording history, which equates to about 60 performances of each mazurka
MethodologyLike before, beat timings extracted using Sonic VisualizerMarkup and manual corrections doneDynamics then extracted as smoothed loudness values
Other musical features ignored, yet important in characterizing a performance: pianists don't play right left hands together; legato and staccato hard to extract but important; tempo and dynamic, useful features (kept), allow listeners to focus their attention on specific areas
Derivations and DefinitionsType-0 score
Plain correlationType-1 score
Nearest neighbor performances in terms of correlation at all timescales
Type-2 scoreRemoving Hatto effect- removing best matches step by step
Type-3 scoreRemoving noise floor
Type-4 scoreOne additional refinement (taking the geometric mean)
Type-0 scoreThis type of correlation is related to dot-product
correlation used in Fourier analysisCorrelation values between extracted musical features
typically have a range between 0.20 and 0.97 for different performances of mazurkas
Though it's hard to only interpret similarity directly from correlation values
Type-0 scoreThe correlation values are consistent only in relation to a
particular composition, and these absolute values cannot be compared directly between different mazurkas
Different compositions will have different expected correlation distributions between performances
Type-1 score In order to compensate partially for this variability in correlation
distributions, scapeplots were developed which only display nearest-neighbor performances in terms of correlation at all timescales for a particular reference performance
Type-2 scoreScape displays are sensitive to Hatto effect:
If an identical performance to the reference, or query, performance is present in the target set of performances, then correlation values at all time resolutions will be close to the maximum value for the identical performance, and the comparative scape plot will show a solid color. All other performances would have an S1 score of approximately 0 regardless of how similar they might otherwise seem to the reference performance
To compensate for this problem, remove the best match from the scape plot in order to calculate the next best match
Type-2 scoreSchematic of nearest-neighbor matching method used in comparative timescapes
Type-3 scoreUsing the concept of noise-floor:
Definition of a performance noise-floor is somewhat arbitrary but splitting the performance database into two equal halves seems the most flexible rule to use
In any case, it is preferable that the noise floor does not appear to have any favored matches, and should consist of uniform small blotches at all timescales in the scape plot representing many different performers as is the example shown
Type-3 score
Type-4 scoreType-3 scores require one additional refinement in order
to be useful since performances are not necessarily evenly distributed in the feature space
Therefore, the geometric mean is used to mix the S3 score with the reverse-query score (S3r)
Type-4 score
EvaluationPresumably pianists will tend to play more like their previous
performances over time rather than like other pianists. If this is true, then better similarity metrics should match two performances by the same pianist more closely to each other than to other performances by different pianists
SourcesSapp, C. S. (2007). Comparative Analysis of Multiple
Musical Performances. In Proceedings of the 8th International Conference on Music Information Retrieval.
Sapp, C. S. (2008). Hybrid Numeric/Rank Similarity Metrics for Musical Performance Analysis. In Proceedings of the 9th International Conference on Music Information Retreival.
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