Rhythmic Reinforcement Modes (Prestø) and Rhythmic Manipulations are important concepts in the study and practice of music and dance. These concepts refer to the ways in which rhythms can be altered, manipulated, or reinforced in order to create different effects or to emphasize certain elements of the composition.
Rhythmic Entropy refers to the level of randomness or uncertainty within a rhythm. A rhythm with high entropy is one that is more unstructured and prone to change, while a rhythm with low entropy is more structured and stable. This concept can be used to describe the rhythmic complexity of a composition and can also be used to analyze the way in which rhythms are used to create different effects in music and dance.
Concerted Rhythmic Reinforcement (Prestø) is when the ensemble builds up under the rhythm of either the main drummer or the main dancer. This ensures that the composition remains in an open and dynamic structure and that the rhythms are reinforced and affirmed. This concept is often used in African-American music and dance, where rhythms are created through a call-and-response pattern.
Accentuated Rhythmic Reinforcement (Prestø) is when the main drummer or dancer “comments” on the ensemble’s rhythm by accentuating it and adding virtuosic phrases that cut across, contrast, or complement the existing rhythms. This can add a layer of complexity and virtuosity to the composition, and can be used to create a sense of drama or tension.
Tonal Rhythmic Alteration refers to the use of simple modifications such as the replacement or alteration of single notes to change the “style” of the rhythm. This can be done by muffling or sharpening sounds, which can change the perception of speed or stress. High-pitched notes can give a sense of speed and sharpness, while low-pitched notes can give a sense of weight, control, and “slowness”.
Spacial Rhythmic Alteration is when the spacing between sounds is altered. This can create a “swing” quality or give a feeling of expansion or contraction of the rhythm and movement. This can be done by omitting beats or by rearranging the beats while maintaining the same meter.
Rhythmic Velocity Alteration is the change of speed of the composition. This can be done by altering the tempo, or by using asymmetric speed changes. In pre-recorded music, the meter is usually maintained as a main reference, but in live music the speed and meter may fluctuate depending on the dancers.
Polyrhythmic Thread Alteration (Prestø) is when one or more rhythmic threads in a polyrhythmic composition change. This can be done by the main drummer playing solo phrases that become more elaborate, fall off, or come back.
Polymetric Thread Alteration (Prestø) is when one or more metric threads in a polymetric composition is altered. This can change the feel and structure of the composition, adding complexity and interest.