Audio morphing

This paper describes the techniques to morph between the two portions of sound originated from a common source, broken because of by some reason. We make use of morphing technique to join the sound where the pitch of the sound slowly changes from one broken part to another broken part by slowly changing the pitch information also covering the unvoiced region of the music. Spectral shapes are encoded on the multidimensional space while pitch on orthogonal axes of it. After matching components of the sound, a morph smoothly interpolates the amplitudes to describe a new sound in the same perceptual space. Finally, by inverting the representation, sound is produced. According to the literature survey, this is the first paper which explains the step by step evolution of one sound resulting into other sound across all states of intermediate steps along with the step by step runtime analysis. This will help researchers in future to improve the morphing methodology by looking carefully into the intermediate steps which decides the overall results. Here, we key out representations for morphing, techniques for matching, and interpolation algorithms and morphing each sound component. Spectral images of complete morph spectrogram are shown in the end.

Il phase vocoder (PV) è uno degli strumenti classici utilizzati nell’ambito digitale per l’analisi e la re-sintesi (synthesis by analysis) di uno spettro sonoro. L’obiettivo principale dell’analisi attraverso PV è quella di separare in maniera indipendente le informazioni temporali da quelle relative allo spettro di un segnale.
Il suo nome deriva storicamente dai primi vocoder (contrazione per “voice encoder”), i quali sviluppavano i concetti di Dudley e utilizzavano una batteria di bandpass filters attraverso i quali passava il segnale da analizzare. Il termine voice indica un primo utilizzo prettamente orientato ai segnali vocali e del parlato.
Nel 1966, James Flanagan e Roger Golden misero a punto una prima versione ai Bell Laboratories ma, rispetto alle intenzioni iniziali, il risultato non fu abbastanza soddisfacente. In seguito, negli anni ’70 venne sviluppata una versione più efficiente del PV implementando al suo interno la Short Time Fourier Transform.

Based on Wishart's literature, this paper investigates the most frequent and significant recorded voice transformation processes, and its correlation with the compos-er's compositional goals, presented on four Trevor Wishart's acousmatic pieces: Vox-5, Tongues of Fire, Globalalia and Encounters in the Republic of Heaven. Although Wishart developed new sound transformations using the phase-vocoder, the selection of the materials takes a key role in determining which sound metamorphosis would fit his aesthetic goal: retain the source credibility from the listener perspective. This articles shows how his compositional goals in each piece demands both specific recorded materials and precise transformation processes in order to achieve his intention with respect to the listener. Hence, one of the main relevant aspects of Wishart's work for electroacoustic composers is to reveal-from the audience point of hearing-subtleties between natural and artificial transformations of voice samples.

Resumo: apresentamos neste artigo uma análise extrativa de C´est um Jardin Secret, Ma Soeur, Ma Fiancée, Une Source Scellée, Une Fontaine Close, obra para viola solo de Tristan Murail. Esta análise tem como objetivo principal expor procedimentos composicionais empregados por Murail, nos quais ele promove transformações graduais do material musical. Neste texto, descreveremos quatro procedimentos específicos: transformações no âmbito das durações e alturas, horizontalização e verticalização temporal de perfis, transformações de timbre e emulação de crossfading.

This work presents a study of the multiphonics of the saxophone from the points of view of timbral analysis and musical performance. A multiphonics categorization into four groups was previously proposed, starting from a musical analysis and further validated by psychophysical experiments and spectral analysis tools. This classification served to identify relevant timbral attributes of the studied multiphonics, such as modulation frequency, spectral center of gravity and roughness. The present work extends the analysis to the spectral morphing of multiphonics, generated by the continuous modification of the playing parameters. These morphings are studied in a comparative view as trajectories in a timbral space, based on the aforementioned attributes, and in terms of their feasibility in the instrument. From this comparative analysis a dynamic characterization of the proposed multiphonic groups is derived.

Resumo: Neste artigo aplicamos o conceito de morphing de áudio na linguagem instrumental em contexto composicional. A primeira seção deste trabalho apresenta a definição de morphing e uma breve contextualização das pesquisas envolvendo a técnica no campo da música eletroacústica. Após esta contextualização apresentamos exemplos de morphing na música instrumental. Na segunda seção do artigo, comentamos em breves relatos a aplicação composicional da técnica e algumas de suas possibilidades em contexto criativo.