Structure Versus Randomness in Computer Music and the Scientific Legacy of Jean-Claude Risset @ JIM

According to Jean-Claude Risset (1938–2016), “art and science bring about complementary kinds of knowledge”. In 1969, he presented his piece Mutations as “[attempting] to explore […] some of the possibilities offered by the computer to compose at the very level of sound—to compose sound itself, so to speak.” In this article, I propose to take the same motto as a starting point, yet while adopting a mathematical and technological outlook, more so than a musicological one.

Instabilities in Convnets for Raw Audio @ IEEE SPL

What makes waveform-based deep learning so hard? Despite numerous attempts at training convolutional neural networks (convnets) for filterbank design, they often fail to outperform hand-crafted baselines. These baselines are linear time-invariant systems: as such, they can be approximated by convnets with wide receptive fields. Yet, in practice, gradient-based optimization leads to suboptimal approximations. In our… Continue reading Instabilities in Convnets for Raw Audio @ IEEE SPL

Kymatio notebooks @ ISMIR 2023

On November 5th, 2023, we hosted a tutorial on Kymatio, entitled “Deep Learning meets Wavelet Theory for Music Signal Processing”, as part of the International Society for Music Information Retrieval (ISMIR) conference in Milan, Italy. The Jupyter notebooks below were authored by Chris Mitcheltree and Cyrus Vahidi from Queen Mary University of London. I. Wavelets… Continue reading Kymatio notebooks @ ISMIR 2023

16 novembre 2023 : journée GdR ISIS “Traitement du signal pour la musique”

Dans le cadre de l’action « Traitement du signal pour l’audio et l’écoute artificielle » du GdR ISIS, nous organisons, le Jeudi 16 Novembre 2023 à l’IRCAM, une troisième journée dédiée au traitement des signaux de musique, animée par les orateurs suivants : Nous invitons tout participant souhaitant présenter ses travaux relevant de l’audio de contacter… Continue reading 16 novembre 2023 : journée GdR ISIS “Traitement du signal pour la musique”

Spectral trancoder: using pretrained urban sound classifiers on undersampled spectral representations @ DCASE

Slow or fast third-octave bands representations (with a frame resp. every 1-s and 125-ms) have been a de facto standard for urban acoustics, used for example in long-term monitoring applications. It has the advantages of requiring few storage capabilities and of preserving privacy. As most audio classification algorithms take Mel spectral representations with very fast… Continue reading Spectral trancoder: using pretrained urban sound classifiers on undersampled spectral representations @ DCASE

Mesostructures: Beyond spectrogram loss in differentiable time-frequency analysis @ JAES

Computer musicians refer to mesostructures as the intermediate levels of articulation between the microstructure of waveshapes and the macrostructure of musical forms. Examples of mesostructures include melody, arpeggios, syncopation, polyphonic grouping, and textural contrast. Despite their central role in musical expression, they have received limited attention in recent applications of deep learning to the analysis and synthesis of musical audio. Currently, autoencoders and neural audio synthesizers are only trained and evaluated at the scale of microstructure: i.e., local amplitude variations up to 100 milliseconds or so. In this paper, we formulate and address the problem of mesostructural audio modeling via a composition of a differentiable arpeggiator and time-frequency scattering. We empirically demonstrate that time-frequency scattering serves as a differentiable model of similarity between synthesis parameters that govern mesostructure. By exposing the sensitivity of short-time spectral distances to time alignment, we motivate the need for a time-invariant and multiscale differentiable time-frequency model of similarity at the level of both local spectra and spectrotemporal modulations.

Fitting Auditory Filterbanks with MuReNN @ IEEE WASPAA

Waveform-based deep learning faces a dilemma between nonparametric and parametric approaches. On one hand, convolutional neural networks (convnets) may approximate any linear time-invariant system; yet, in practice, their frequency responses become more irregular as their receptive fields grow. On the other hand, a parametric model such as LEAF is guaranteed to yield Gabor filters, hence an optimal time-frequency localization; yet, this strong inductive bias comes at the detriment of representational capacity. In this paper, we aim to overcome this dilemma by introducing a neural audio model, named multiresolution neural network (MuReNN). The key idea behind MuReNN is to train separate convolutional operators over the octave subbands of a discrete wavelet transform (DWT). Since the scale of DWT atoms grows exponentially between octaves, the receptive fields of the subsequent learnable convolutions in MuReNN are dilated accordingly. For a given real-world dataset, we fit the magnitude response of MuReNN to that of a wellestablished auditory filterbank: Gammatone for speech, CQT for music, and third-octave for urban sounds, respectively. This is a form of knowledge distillation (KD), in which the filterbank “teacher” is engineered by domain knowledge while the neural network “student” is optimized from data. We compare MuReNN to the state of the art in terms of goodness of fit after KD on a hold-out set and in terms of Heisenberg time-frequency localization. Compared to convnets and Gabor convolutions, we find that MuReNN reaches state-of-the-art performance on all three optimization problems.

PhD offer: “Theory and implementation of multi-resolution neural networks”

The French national center for scientific research (CNRS) is hiring a PhD student as part of a three-year project on “Multi-Resolution Neural Networks” (MuReNN). MuReNN is supported by the French national funding agency (ANR), and hosted at the Laboratoire des Sciences du Numérique de Nantes (LS2N). A collaboration with the Austrian Academy of Sciences is… Continue reading PhD offer: “Theory and implementation of multi-resolution neural networks”