Author: Richard Graham
The implementation of real-time music technology within an improvisatory performance practice raises a series of issues concerning perceptual relationships between the performer, musical gesture, and resultant sound structure. The following paper will include a presentation of a live performance system constructed in Pure Data which exploits a polyphonic audio output of an electric guitar in order to create dense polyphonic music structures. The system provides pitch data for each string in order to construct relevant pitch class contour (figurative gesture) information in real-time. The contour information is then interpolated and assigned to a series of spatial and timbral synthesis parameters in order to create a series of new gestural relationships between the performer and resulting sonority. Overall, the presentation will highlight the salience of contour in the construction and perceptual auditory organisation of polyphonic music structures.
The aforementioned performance issues extend throughout a series of performance related domains concerning the perception of gestural interaction between the performer, their instrument, and the resultant acoustic event. The computer undoubtedly extends the compositional palette of the individual performing musician beyond pitch primacy conventions, allowing potential development of dense polyphonic textures over time. However, the retention and comprehension of such “polyphony of polyphonies” becomes increasingly difficult in proportion to the density of acoustic events , which may challenge audiovisual schema associated with linear completion and other forms of musical or instrumental expectancy. One may consider “envelopes as a means for thematic evolution,” to be treated as an “open gesture” in order to create a “memorable shape,” perceivable as a “meaningful scheme” at various hierarchical levels of musical structure by reflecting the same morphological contour amongst transformative processes, particularly in the case of more dense polyphonic music structures . Such an approach may potentially allow further comprehensibility of complex polyphonic structures as they unfold in real-time . One may further develop more meaningful, or at least more relevant envelopes by utilising the contour of incoming pitch class data in real-time practice. A further benefit to be found in the utilisation of a constant incoming stream of performance data is the potential mapping of relevant performance data to concurrent real-time morphological transformations, rather than a transformation occurring after a conditional algorithm is satisfied. The author proposes a theoretically grounded live performance system which exploits relevant schemata in order to evoke conscious, consistent evaluation and interaction between the performer and perceived acoustic patterns produced by a live performance system. It would seem logical, then, to develop a strong theoretical underpinning based on relevant research to function as the crux of a computer based performance practice in order to “address matters of interactivity, density, polyphony and comprehensibility across rehearsals and performances”. By extending understanding of the cognitive constraints surrounding perception of musical structure, one creates an opportunity to formulate useful compositional strategies which may be utilised within a live performance system. Methods of music (scene) analysis will be considered in order to improve comprehensibility of potentially dense polyphonic structures and how the listener may retain such music structure in memory. This paper will also consider theoretical research concerning compositional concepts relevant to the instrument, which may potentially provide further useful performance data to be utilised within a constructed live performance system in order to further exploit the polyphonic audio pickup system and relevant schemata. Performance strategies will then be constructed and presented within a live performance system constructed in Pure Data.
4th international Pure Data Convention 2011 Weimar ~ Berlin