This work is related to the imitative synthesis of complex instrumental gestures in guitar music using a score-based control scheme. Our specific goal is to simulate the rasgueado technique that is popular especially in flamenco music and is also used in the classical guitar repertoire. Rasgueado is especially challenging, since ordinary music notation is inadequate to represent the dense stream of notes required for a convincing simulation. We take three approaches to achieve our task. First, we use the practical knowledge of how the actual performance is accomplished by the human player. Second, photographs and high-speed videos of the player's gesture are inspected to obtain information about the timing and order of finger-string contacts. Third, as a complementary approach we analyze audio excerpts from real guitar playing and using onset detection techniques extract candidate values for the onset times and the amplitudes for each event. Finally, we combine the results from the three analysis steps using a constraint-based approach to find possible pitch and fingering sequences. We translate our findings to a macro-note scheme that allows algorithmically filling a musical score, which controls a waveguide guitar synthesizer.

Sent for review to IEEE Journal of Selected Topics in Signal Processing.

Recorded Sound
• Recorded rasqueado roll for all open strings.
• Highpass filtered and slower rasqueado roll. The corner frequency of the highpass filter was 11 kHz and the playback speed is 80% slower than the original speed.

Synthesized examples
• Single plucks - Normal style. Synthesis of open strings with an excitation signal derived from normal plucks.
• Rasqueado roll synthesis - Normal pluck excitation. Synthesis of a rasqueado roll using excitation signals derived from normal plucks.
• Single rasqueado/hard plucks - Rasqueado style. Synthesis of open strings with excitation signals derived from single rasqueado/hard plucks.
• Rasqueado roll synthesis - Rasqueado/hard pluck excitation. Synthesis of a rasqueado roll using excitation signals derived from single rasqueado/hard plucks.
• Fast rasqueado roll synthesis - Rasqueado/hard pluck excitation. Synthesis of a fast rasqueado roll using excitation signals derived from single rasqueado/hard plucks.
• Continuous rasqueado roll synthesis - Rasqueado/hard pluck excitation. Synthesis of a continuous rasqueado roll using excitation signals derived from single rasqueado/hard plucks.
• Musical excerpt from Concierto de Aranjuez by J. Rodrigo. This example contains macro-note rasgueado effects, ordinary chords, single notes, and scales.

Normal speed
• Normal speed video of rasqueado gesture (all open strings).

Slow motion (240 frames per sec.)
• High speed video of a rasqueado gesture in slow motion 10% of original speed (no sound). The top plate of the guitar is covered with white paper and the unwound (thinnest) strings have been colored dark for improved visibility.

Link to the detialed macro rules presented in LISP can be found [HERE].

Rasgueado (also called Rajeo, Rasgueo or Rasgeo in Andalusian dialect and Flamenco jargon) is a guitar finger strumming technique commonly associated with flamenco guitar music. It is also used in classical and other fingerstyle guitar picking techniques. The rasgueado is executed using the fingers of the strumming hand in rhythmically precise, and often rapid, strumming patterns. (see http://en.wikipedia.org/wiki/Rasgueado for more details)

PWGL is a free cross-platform visual language specialized in computer aided composition and sound synthesis. All the score and synthesis examples of this article have been implemented using PWGL.