Da emergência da sonoridade às sonoridades emergentes: mediação tecnológica, emergentismo e a criação sonora com suporte computacional

Apresentamos uma visão panorâmica e crí­tica de como o uso computador enquanto artefato de criação musical pode retroagir sobre os próprios modelos composicionais mediados por este. De maneira similar às mudanças de paradigma que o uso de dispositivos de gravação trouxe à criação musical, emergindo disto a sonoridade como um aspecto central do discurso sonoro, o uso de computadores tem potencializado novos campos de ação criativa não orientados à determinação das estruturas da obra em si, mas à criação de condições ambientais favoráveis ao surgimento de estruturas como um aspecto emergente da própria interação entre as partes do sistema. A partir da discussão de distintos modelos composicionais, trataremos como a criação com suporte computacional tem sido explorada como aporte à emergência de novas estruturas

Ηχητικά Είδη: Ηλεκτροακουστική σύνθεση με Στοιχειώδη Κυτταρικά Αυτόματα και Game of Life

Τα κυτταρικά αυτόματα ως υπολογιστικό μοντέλο εντοπίζονται, μέσω των συνεχώς αυξανόμενων εφαρμογών τους, σε ένα εύρος επιστημονικών κλάδων και τεχνών. Το χαρακτηριστικότερο γνώρισμα των κυτταρικών αυτομάτων είναι η δυνατότητα απρόβλεπτης συμπεριφοράς η οποία όμως προκύπτει ή αναδύεται από πολύ απλούς κανόνες. Τα είδη αυτομάτων στα οποία μπορεί κανείς να παρατηρήσει με σαφήνεια τη συμπεριφορά που περιγράφουμε είναι αυτά που ακολουθούν και τους απλούστερους κανόνες. Για το λόγο αυτό επιλέξαμε να χρησιμοποιήσουμε για τη μουσική δημιουργία τα στοιχειώδη κυτταρικά αυτόματα (elementary cellular automata) και το Game of Life, δυο συστήματα με πολύ απλές αρχές λειτουργίας. Η μελέτη των συστημάτων αυτών έγινε παράλληλα με τη διερεύνηση του διεπιστημονικού υποβάθρου αλλά και συναφών φιλοσοφικών εννοιών όπως αυτή της ανάδυσης και του δυισμού μορφής - ύλης που έχουν αφετηρία τις θεωρίες του Αριστοτέλη. Ως το μεγαλύτερο μέρος της εργασίας αυτής, δημιουργήθηκε ένα μουσικό έργο σε δύο μέρη τα οποία αποτελούν δύο ξεχωριστές εκτελέσεις σε ένα σύστημα που δημιουργήσαμε στο Max/MSP όπου αξιοποιούνται δύο αλγόριθμοι στοιχειωδών κυτταρικών αυτομάτων και το Game of Life παράλληλα. Βαρύτητα ιδιαίτερη δόθηκε στη δυνατότητα των μερών του συστήματος να επικοινωνούν μεταξύ τους με τρόπο που να αποφεύγεται η προβλεψιμότητα αλλά και η αίσθηση της τυχαιότητας στο μουσικό αποτέλεσμα.Cellular automata as a computational model can be found, through their constantly increasing applications, in a wide field of studies and arts. Typical trait of cellular automata is the capability of producing unpredictable behaviour which, however, comes or emerges from simple rules. The kinds of cellular automata in which one can observe with clarity their behaviour, is the ones that follow the simplest rules. That is why we chose the Elementary Cellular Automata and the Game of Life in order to create music. The study of these systems was done in parallel with researching of the interdisciplinary background as well as relevant philosophical notions, such as that of Emergence and the dualism of Form – Matter which derive from Aristotle’s theories. As the major part of this thesis, a musical work in two parts was made with a Max/MSP system that uses algorithms for Elementary Cellular Automata and the Game of Life, in parallel. From a musical perspective, the focal point was placed in the capability of communication between different parts of the system in a way that either predictability or complete randomness is avoided

SOUND SYNTHESIS WITH CELLULAR AUTOMATA

This thesis reports on new music technology research which investigates the use of cellular automata (CA) for the digital synthesis of dynamic sounds. The research addresses the problem of the sound design limitations of synthesis techniques based on CA. These limitations fundamentally stem from the unpredictable and autonomous nature of these computational models. Therefore, the aim of this thesis is to develop a sound synthesis technique based on CA capable of allowing a sound design process. A critical analysis of previous research in this area will be presented in order to justify that this problem has not been previously solved. Also, it will be discussed why this problem is worthwhile to solve. In order to achieve such aim, a novel approach is proposed which considers the output of CA as digital signals and uses DSP procedures to analyse them. This approach opens a large variety of possibilities for better understanding the self-organization process of CA with a view to identifying not only mapping possibilities for making the synthesis of sounds possible, but also control possibilities which enable a sound design process. As a result of this approach, this thesis presents a technique called Histogram Mapping Synthesis (HMS), which is based on the statistical analysis of CA evolutions by histogram measurements. HMS will be studied with four different automatons, and a considerable number of control mechanisms will be presented. These will show that HMS enables a reasonable sound design process. With these control mechanisms it is possible to design and produce in a predictable and controllable manner a variety of timbres. Some of these timbres are imitations of sounds produced by acoustic means and others are novel. All the sounds obtained present dynamic features and many of them, including some of those that are novel, retain important characteristics of sounds produced by acoustic means

Automated manipulation of musical grammars to support episodic interactive experiences

Music is used to enhance the experience of participants and visitors in a range of settings including theatre, film, video games, installations and theme parks. These experiences may be interactive, contrastingly episodic and with variable duration. Hence, the musical accompaniment needs to be dynamic and to transition between contrasting music passages. In these contexts, computer generation of music may be necessary for practical reasons including distribution and cost. Automated and dynamic composition algorithms exist but are not well-suited to a highly interactive episodic context owing to transition-related problems including discontinuity, abruptness, extended repetitiveness and lack of musical granularity and musical form. Addressing these problems requires algorithms capable of reacting to participant behaviour and episodic change in order to generate formic music that is continuous and coherent during transitions. This thesis presents the Form-Aware Transitioning and Recovering Algorithm (FATRA) for realtime, adaptive, form-aware music generation to provide continuous musical accompaniment in episodic context. FATRA combines stochastic grammar adaptation and grammar merging in real time. The Form-Aware Transition Engine (FATE) implementation of FATRA estimates the time-occurrence of upcoming narrative transitions and generates a harmonic sequence as narrative accompaniment with a focus on coherent, form-aware music transitioning between music passages of contrasting character. Using FATE, FATRA has been evaluated in three perceptual user studies: An audioaugmented real museum experience, a computer-simulated museum experience and a music-focused online study detached from narrative. Music transitions of FATRA were benchmarked against common approaches of the video game industry, i.e. crossfading and direct transitions. The participants were overall content with the music of FATE during their experience. Transitions of FATE were significantly favoured against the crossfading benchmark and competitive against the direct transitions benchmark, without statistical significance for the latter comparison. In addition, technical evaluation demonstrated capabilities of FATRA including form generation, repetitiveness avoidance and style/form recovery in case of falsely predicted narrative transitions. Technical results along with perceptual preference and competitiveness against the benchmark approaches are deemed as positive and the structural advantages of FATRA, including form-aware transitioning, carry considerable potential for future research

Computational and Psycho-Physiological Investigations of Musical Emotions

The ability of music to stir human emotions is a well known fact (Gabrielsson & Lindstrom. 2001). However, the manner in which music contributes to those experiences remains obscured. One of the main reasons is the large number of syndromes that characterise emotional experiences. Another is their subjective nature: musical emotions can be affected by memories, individual preferences and attitudes, among other factors (Scherer & Zentner, 2001). But can the same music induce similar affective experiences in all listeners, somehow independently of acculturation or personal bias? A considerable corpus of literature has consistently reported that listeners agree rather strongly about what type of emotion is expressed in a particular piece or even in particular moments or sections (Juslin & Sloboda, 2001). Those studies suggest that music features encode important characteristics of affective experiences, by suggesting the influence of various structural factors of music on emotional expression. Unfortunately, the nature of these relationships is complex, and it is common to find rather vague and contradictory descriptions. This thesis presents a novel methodology to analyse the dynamics of emotional responses to music. It consists of a computational investigation, based on spatiotemporal neural networks sensitive to structural aspects of music, which "mimic" human affective responses to music and permit to predict new ones. The dynamics of emotional responses to music are investigated as computational representations of perceptual processes (psychoacoustic features) and self-perception of physiological activation (peripheral feedback). Modelling and experimental results provide evidence suggesting that spatiotemporal patterns of sound resonate with affective features underlying judgements of subjective feelings. A significant part of the listener's affective response is predicted from the a set of six psychoacoustic features of sound - tempo, loudness, multiplicity (texture), power spectrum centroid (mean pitch), sharpness (timbre) and mean STFT flux (pitch variation) - and one physiological variable - heart rate. This work contributes to new evidence and insights to the study of musical emotions, with particular relevance to the music perception and emotion research communities