Pragmatic Considerations in Mixed Music: a Case Study of La Rage

With access to powerful real-time DSP languages now easier than ever, the new generation of mixed music composers are able to manage both sides of the coin: they have the programming skills and the compositional concerns that were traditionally the responsibility of two different persons. This brings more and more sophisticated integration of technical resources and compositional gestures. A good example of such integration is the author’s piece La Rage. In the light of general comments on the seamless integration of technology in this piece, the author, by discussing how compositional and technical concerns interact in his process of creation, tries to pinpoint key considerations that help him achieve this. He proposes two major categories, portability and adaptability, and explains how they were addressed in this specific work

Thinking Inside the Box: A New Integrated Approach to Mixed Music Composition and Performance

The Thinking Inside the Box project (TItB) seeks to address pragmatic concerns inherent to mixed music performance, and proposes ways to better consider the sound of the acoustic reality of the concert space at studio composition time. This is achieved through empirical investigation into subversive use of recent developments in hardware and software technologies. The primary concerns are (1) optimising the integration of live instruments and electroacoustic sound in the concert hall environment for both the performers and the public, by carefully choosing loudspeaker types and placement at commission time, and by avoiding sound reinforcement; (2) minimizing for studio composers the insitu trauma of the first live rendition of the piece, by bringing the concert hall acoustic environment into the studio composition process, using convolution reverb to reproduce in the studio the given loudspeaker setup through its impulse responses. This paper presents the conclusions of the project's early experiments in the form of three case study sets, and describes how this approach will be of use for any composer of mixed music

Surfing the Waves: Live Audio Mosaicing of an Electric Bass Performance as a Corpus Browsing Interface

In this paper, the authors describe how they use an electric bass as a subtle, expressive and intuitive interface to browse the rich sample bank available to most laptop owners. This is achieved by audio mosaicing of the live bass performance audio, through corpus-based concatenative synthesis (CBCS) techniques, allowing a mapping of the multi-dimensional expressivity of the performance onto foreign audio material, thus recycling the virtuosity acquired on the electric instrument with a trivial learning curve. This design hypothesis is contextualised and assessed within the Sandbox#n series of bass+laptop meta-instruments, and the authors describe technical means of the implementation through the use of the open-source CataRT CBCS system adapted for live mosaicing. They also discuss their encouraging early results and provide a list of further explorations to be made with that rich new interface

Tuning to Trust: System Calibration as Creative Enabler

This paper presents a mixed-music composition methodology emerging from the author’s latest practice-based research in the field over the last five years. The calibration of the interactive performance systems has enabled trust in reproducible sound quality for both the composer and the performers, enhancing the portability and adaptability of the works, and permitting increasingly daring creative experiments without compromising the rehearsal and concert experiences. A set of general, transferable responsibilities and solutions are presented and assessed against clear design criteria in the author’s latest pieces

Stochastic mesh approximations for dynamic hedging with costs

Cette thèse se concentre sur le calcul de la solution optimale d'un problème de couverture de produit dérivé en temps discret. Le problème consiste à minimiser une mesure de risque, définie comme l'espérance d'une fonction convexe du profit (ou perte) du portefeuille, en tenant compte des frais de transaction. Lorsqu'il y a des coûts, il peut être optimal de ne pas transiger. Ainsi, les solutions sont caractérisées par des frontières de transaction. En général, les politiques optimales et les fonctions de risque associées ne sont pas connues explicitement, mais une stratégie bien connue consiste à approximer les solutions de manière récursive en utilisant la programmation dynamique. Notre contribution principale est d'appliquer la méthode du maillage stochastique. Cela permet d'utiliser des processus stochastiques multi-dimensionels pour les dynamiques de prix. On obtient aussi des estimateurs biasés à la hausse et à la baisse, donnant une mesure de la proximité de l'optimum. Nous considérons différentes façons d'améliorer l'efficacité computationelle. Utiliser la technique des variables de contrôle réduit le bruit qui provient de l'utilisation de prix de dérivés estimés à même le maillage stochastique. Deux autres techniques apportent des réductions complémentaires du temps de calcul : utiliser une grille unique pour les états du maillage et utiliser une procédure de "roulette Russe". Dans la dernière partie de la thèse, nous présentons une application pour le cas de la fonction de risque exponentielle négative et un modèle à volatilité stochastique (le modèle de Ornstein-Uhlenbeck exponentiel). Nous étudions le comportement des solutions sous diverses configurations des paramètres du modèle et comparons la performance des politiques basées sur un maillage à celles d'heuristiques.This thesis focuses on computing the optimal solution to a derivative hedging problem in discrete time. The problem is to minimize a risk measure, defined as the expectation of a convex function of the terminal profit and loss of the portfolio, taking transaction costs into account. In the presence of costs, it is sometimes optimal not to trade, so the solutions are characterized in terms of trading boundaries. In general, the optimal policies and the associated risk functions are not known explicitly, but a well-known strategy is to approximate the solutions recursively using dynamic programming. Our central innovation is in applying the stochastic mesh method, which was originally applied to option pricing. It allows exibility for the price dynamics, which could be driven by a multi-dimensional stochastic process. It also yields both low and high biased estimators of the optimal risk, thus providing a measure of closeness to the actual optimum. We look at various ways to improve the computational efficiency. Using the control variate technique reduces the noise that comes from using derivative prices estimated on the stochastic mesh. Two additional techniques turn out to provide complementary computation time reductions : using a single grid for the mesh states and using a so-called Russian roulette procedure. In the last part of the thesis, we showcase an application to the particular case of the negative exponential risk function and a stochastic volatility model (the exponential Ornstein-Uhlenbeck model). We study the behavior of the solutions under various configurations of the model parameters and compare the performance of the mesh-based policies with that of well-known heuristics

Rich Contacts: Corpus-Based Convolution of Audio Contact Gestures for Enhanced Musical Expression

We propose ways of enriching the timbral potential of gestural sonic material captured via piezo or contact microphones, through latency-free convolution of the microphone signal with grains from a sound corpus. This creates a new way to combine the sonic richness of large sound corpora, easily accessible via navigation through a timbral descriptor space, with the intuitive gestural interaction with a surface, captured by any contact microphone. We use convolution to excite the grains from the corpus via the microphone input, capturing the contact interaction sounds, which allows articulation of the corpus by hitting, scratching, or strumming a surface with various parts of the hands or objects. We also show how changes of grains have to be carefully handled, how one can smoothly interpolate between neighbouring grains, and finally evaluate the system against previous attempts

Estimating the inverse trace using random forests on graphs

Some data analysis problems require the computation of (regularised) inverse traces, i.e. quantities of the form \Tr (q \bI + \bL)^{-1}. For large matrices, direct methods are unfeasible and one must resort to approximations, for example using a conjugate gradient solver combined with Girard's trace estimator (also known as Hutchinson's trace estimator). Here we describe an unbiased estimator of the regularized inverse trace, based on Wilson's algorithm, an algorithm that was initially designed to draw uniform spanning trees in graphs. Our method is fast, easy to implement, and scales to very large matrices. Its main drawback is that it is limited to diagonally dominant matrices \bL.Comment: Submitted to GRETSI conferenc