ESTEBAN MAESTRE
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Below I describe a few representative examples of recent work, along with some illustrative images, demonstrative sounds/videos, etc. Feel free to contact me for further material.





SIMULATION OF HEAD RELATED TRANSFER FUNCTIONS




Through a modified state-space filter structure allowing a time-varying number of inputs, it is possible to efficiently simulate the minimum-phase part of head related transfer functions (HRTF) at low computational cost, no convolution, while allowing for perceptually motivated warped frequency resolutions and reception of multiple wavefronts of time-varying direction. In the left plots, modeled HRTF spectra designed over linear frequency resolutions. In the right plots, modeled HRTF spectra designed over warped frequency resolutions. Top to bottom plots, increasing modeling order: 8,16,32.

https://hal.archives-ouvertes.fr/hal-02275169





SIMULATION OF SOUND SOURCE DIRECTIVITY




Through a modified state-space filter structure allowing a time-varying number of outputs, it is possible to simulate sound source directivity at low computational cost, no convolution, within geometric acoustic frameworks. With applicability in sound synthesis and/or auralization within virtual environments where sound sources change position and orientation dynamically, directivity profiles can be modeled on perceptually motivated warped frequency axes, with alternatives for representing directivity on a per-vibration-mode basis or by reduced-order efficient representations. In the right plots, spectra of the radiation transfer function of a rotating violin and clarinet (top: measured; bottom: simulated).

https://hal.archives-ouvertes.fr/hal-02275169





AUTOMATIC PERFORMANCE ON PHYSICAL MODELS




Through synthetic bowing control signals rendered from an annotated traditional score via a generative model trained from motion capture data, it is possible to drive a fairly simple bowed string physical model to obtain natural-sounding expressive violin performances:







REAL-TIME INTERACTIVE CONTROL OF PHYSICAL MODELS




By coupling digital waveguides and modal synthesis it is possible to construct highly efficient, yet realistic physical models ready for interactive control. At the link below it is possible to watch and illustrative example of violin synthesis model controlled via a laptop trackpad. The model, which uses less than 5% of the CPU power of a 2013 Macbook Air, incorporates a thermal friction model implemented via a one-dimensional finite-difference scheme coupled to the bow-string nonlinear interaction mechanism:







EFFICIENCY OF HYBRID PHYSICAL MODELS



To illustrate the effciency and fidelity offered by coupling modal synthesis and digital waveguides, a example of synthetic guitar string plucks is provided here. The model, constructed from automated processing of a fairly reduced set of simple vibroacoustic measurements on an acoustic guitar, emulates the 2D motion of 6 strings, string-string coupling, string-body coupling, and body radiativity. In one core of a 2013 laptop, it is possible simultaneously run about 40 of such models:







MODAL REVERBERATION




Modal reverberation offers great advantages: efficiency, flexibility, zero-delay, parallel implementation, etc. Moreover, it supports a dynamic representation of a space, at a fixed cost, so that one may simulate walking through the space or listening to a moving source by simply changing the coeffcients of the fixed modes being summed. Below I point to a few examples of static reverberation models obtained via a pole optimization technique presented at DAFX 2017:

http://ccrma.stanford.edu/~esteban/modrev/dafx2017





MULTIMODAL ANALYSIS - RESEARCH REPRODUCIBILITY






In the context of string quartet performance analysis, I envisioned, promoted, and led the development of Repovizz. The Repovizz system comprises a remote hosting platform and a data archival protocol through which data of different modalities can be stored, visualized, annotated, and selectively retrieved via a web interface and a dedicated API. A video demonstration and the project website can be respectively accessed at:

http://repovizz.upf.edu
Esteban Maestre, 2020