Adjusting the Spectral Envelope Evolution of Transposed Sounds with Gabor Mask Prototypes

International audienceAudio samplers often require to modify the pitch of recorded sounds in order to generate scales or chords. This article tackles the use of Gabor masks and their capacity to improve the perceptual realism of transposed notes obtained through the classical phase-vocoder algorithm. Gabor masks can be seen as operators that allows the modification of time-dependent spectral content of sounds by modifying their time-frequency representation. The goal here is to restore a distribution of energy that is more in line with the physics of the structure that generated the original sound. The Gabor mask is elaborated using an estimation of the spectral envelope evolution in the time-frequency plane, and then applied to the modified Gabor transform. This operation turns the modified Gabor transform into another one which respects the estimated spectral envelope evolution, and therefore leads to a note that is more perceptually convincing

ESPRIT in Gabor Frames

International audienceThis articles tackles the estimation of mode parameters in recorded sounds of resonant objects. High resolution methods such as the ESPRIT method have already proved to be of great use for this sort of purpose. However, these methods being model-sensitive, their application to real-life audio signals can lead to results that are not satisfactory enough for a consistent re-synthesis. This is especially the case when the computational cost makes it impossible to analyse the signal in totality, or when the signal presents a high number of components. Significant improvements have already been achieved by decomposing the signal into several sub-band filtered versions, and by applying the ESPRIT algorithm on each of the resulting signals. It is shown in this article that the ESPRIT algorithm can be efficiently applied on time-frequency representations of the signal obtained using Gabor frames. Numerical tests that highlight the advantages of such an approach are also detailed. In addition to the advantages offered by the sub-band approach, the solid Gabor frame formalism combined with the ESPRIT method allows a flexible and sharp analysis on selected regions of the time-frequency plane, and leads to re-synthesis which are perceptually very close to the original sounds

Analyse modale de sons d'impact par méthodes haute résolution pour la catégorisation perceptive des matériaux.

Faire le lien entre la morphologie d'un signal sonore et certains de ses attributs perceptifs est une étape capitale dans l'élaboration d'un synthétiseur proposant un contrôle intuitif. Certains aspects de cette morphologie peuvent être caractérisés au moyen de "descripteurs acoustiques". Lorsqu'ils sont choisis judicieusement, ces descripteurs permettent de classer des signaux dans des catégories ayant un sens perceptif ; ceci permet d'établir un lien entre morphologie et perception. Dans le travail présenté ici, on s'intéresse en particulier à la catégorisation perceptive de sons d'impact.La plupart des descripteurs considérés ici se construisent à partir d'une modélisation paramétrique du signal. Dans notre cas, la modélisation la plus appropriée semble être la décomposition en somme de sinusoïdes amorties. Une estimation stable et rigoureuse des paramètres du modèle étant essentielle au calcul des descripteurs, on se penche sur la comparaison de plusieurs méthodes de décomposition. Il ressort que la méthode à haute résolution ESPRIT semble la plus indiquée, mais qu'elle ne peut pas être utilisée sous sa forme classique. On propose donc différentes adaptations. En particulier, on s'intéresse à l'application d'ESPRIT dans des repères de Gabor. En outre, on propose des méthodes pour maximiser le caractère parcimonieux de la décomposition.On étudie finalement un cas d'application concret : à partir d'une banque de sons enregistrés en chambre anéchoïque résultant d'impacts sur divers objets du quotidien, on évalue la pertinence d'un ensemble de descripteurs pour la catégorisation en fonction du matériau perçu.Linking an audio signal morphology with some of its perceptual attributes is a key step when elaborating a intuitively controlled synthesizer. Some of these morphology aspects can be characterized using "acoustical descriptors". When chosen wisely, descriptors can allow a classification of audio signals in categories which are perceptually relevant ; in such cases, this approach establishes a link between morphology and perception. The present work focuses on the perceptual categorization of impact sounds.Most of the descriptors proposed here are computed using a parametrized description of the signal. Here, the most appropriate parametrization seems to be a decomposition in exponentially damped sinusoids. A robust and stable estimation of the model parameters being essential to the computation of relevant descriptors, different parametrization methods are described and compared. From these comparisons, it appears that the high-resolution method ESPRIT is the most appropriate, but that it cannot be applied in its classical form. Several adaptations are therefore investigated. In particular, the application of ESPRIT in Gabor frames is considered. Besides, a method is proposed in order to minimize the number of components necessary for a satisfactory decomposition.Finally, a concrete application is addressed : from an impact sounds bank recorded in an anechoic chamber, elaborated with a wide range of everyday-life objects, the relevance of several acoustical descriptors for the perceptual categorization of the perceived material is investigated

Modal Analysis of Impact Sounds with ESPRIT in Gabor Transforms

International audienceIdentifying the acoustical modes of a resonant object can be achieved by expanding a recorded impact sound in a sum of damped sinusoids. High-resolution methods, e.g. the ESPRIT algorithm, can be used, but the time-length of the signal often requires a sub-band decomposition. This ensures, thanks to sub-sampling, that the signal is analysed over a significant duration so that the damping coefficient of each mode is estimated properly, and that no frequency band is neglected. In this article, we show that the ESPRIT algorithm can be efficiently applied in a Gabor transform (similar to a sub-sampled short-time Fourier transform). The combined use of a time-frequency transform and a high-resolution analysis allows selective and sharp analysis over selected areas of the time-frequency plane. Finally, we show that this method produces high-quality re-synthesized impact sounds which are perceptually very close to the original sounds

Actes de la conférence CAID 2021 (Conference on Artificial Intelligence for Defense)

6th European Cyber Week (6ème semaine européenne de la cybersécurité et de la cyberdéfense

Actes de la conférence CAID 2021 (Conference on Artificial Intelligence for Defense)

6th European Cyber Week (6ème semaine européenne de la cybersécurité et de la cyberdéfense

Actes de la conférence CAID 2021 (Conference on Artificial Intelligence for Defense)

6th European Cyber Week (6ème semaine européenne de la cybersécurité et de la cyberdéfense)International audienc

Actes de la conférence CAID 2021 (Conference on Artificial Intelligence for Defense)

6th European Cyber Week (6ème semaine européenne de la cybersécurité et de la cyberdéfense)International audienc

Actes de la conférence CAID 2021 (Conference on Artificial Intelligence for Defense)

6th European Cyber Week (6ème semaine européenne de la cybersécurité et de la cyberdéfense)International audienc

Actes de la conférence CAID 2021 (Conference on Artificial Intelligence for Defense)

6th European Cyber Week (6ème semaine européenne de la cybersécurité et de la cyberdéfense)International audienc