De- and recomposition of expression in music performance - demo page

On this page a demonstration by means of soundfiles is given, as an addition to section 3.3 of the final thesis of Michiel Borkent which can be found in the link at the bottom of this page.

In short, the system can decompose expressive timing in a performance, guided by a structural description of the music, into timing profiles that correspond with the structural units in the music, such as phrases, bars and ritards.

Using the results from the decomposition, the timing can be recomposed, using a set of weights that control the contributions of the timing profiles. For example, if one wants to filter out all the ritards but wants to keep the other timing intact, the weight for the ritards is set to 0, and the other weights to 1 .

To demonstrate some concrete results from this project, three performances were generated, using one original performance.

Original
MP3    
This is the piece as it is originally played by a professional pianist. The piece used is the theme from Beethoven's six variations in G-major WoO 70 (1795) on the duet "Nel cor piu non mi sento" from the opera "La Molinara" by Giovanni Paisiello.

Ragtime
MP3    
Ragtime features highly exaggerated eighth note figure (almost sounds like sixteenth-eighth-sixteenth) in accompaniment, and exaggerated attention to the fermatas.

Romantic
MP3    
Romantic features long, full phrases in the melody, evenly spaced eighth notes in the accompaniment, and understated fermatas.

Renaissance
MP3    
Renaissance alters the Classical pattern in the accompaniment, so instead of short-long-short, it becomes long-short-short, somewhat more characteristic of Renaissance dance music. In order to maintain danceability, ritards are minimized.

All of the above performances are characterized by their expressive timing patterns, as it is called in scientific terms. Expressive timing is the deviation a performer uses to in relation to the structure of the music, like long phrases in the romantic performance. Expressive timing can be seen as deviation from the global tempo. A demonstration of a performance without deviation from the global tempo can be heard hereunder.
Mechanical
MP3    
Renaissance alters the Classical pattern in the accompaniment, so instead of short-long-short, it becomes long-short-short, somewhat more characteristic of Renaissance dance music. In order to maintain danceability, ritards are minimized.


Of the deviation of global tempo a diagram can be made. Because in the previous example the performer does not deviate from global tempo anywhere, the diagram is just a horizontal line. See Figure 1.

Figure 1: mechanical timing


In our system this corresponds with a recomposition with the timing profiles all amplified with a weight 0. In other words, all expressive timing is muted and only global tempo remains.

Table 1: Recomposition - mechanical timing
Structural unit weight
48-phrase 0
36-phrase 0
12-phrase 0
3-phrase 0
bar 0
leap 0
ritard 0
chord-ritard 0


Conversely, a remix with all weights put to 1 corresponds with the expressive timing just as in the original performance. See Table 2 and Figure 2.

Figure 2: reconstructed performance timing
Table 2: Recomposition - original performance timing
Structural unit weight
48-phrase 1
36-phrase 1
12-phrase 1
3-phrase 1
bar 1
leap 1
ritard 1
chord-ritard 1


The weights and expressive timing diagram of ragtime are as follows. See Table 3 and Figure 3.

Figure 3: expressive timing diagram of ragtime
Table 3: Recomposition - ragtime
Structural unit weight
48-phrase 0.2
36-phrase 0.2
12-phrase 0
3-phrase 2.5
bar 0.2
leap 0
ritard 1
chord-ritard 1


The expressive timing signal of romantic is given in Figure 4 and the corresponding weights in Table 4.

.
Figure 4: romantic expressive timing
Table 4: Recomposition - Romantic
Structural unit weight
48-phrase 0
36-phrase 0
12-phrase 3
3-phrase 0
bar 0
leap 0
ritard 0
chord-ritard 0


The weights of Renaissance are given in Table 5 and the resulting expressive timing profile in Figure 5.

Figure 5: renaissance expressive timing
Table 5: Recomposition - renaissance
Structural unit weight
48-phrase 0
36-phrase 0
12-phrase 0
3-phrase -3.3
bar 0
leap 0
ritard 0
chord-ritard 0


Thanks go out to Ben Turner (a music psychology graduate from Ohio State University) who tweaked and found out what configuration weigths simulate the several styles.

More information about the work of the author of this page can be found at http://www.pictureofthemoon.net/~borkent/work