Laurent Millot

Ecole Nationale Supérieure Louis-Lumière · Sound Engineering

Dans [1] on a proposé une correction des définitions classiques des paquets d'ondes afin de tenir compte du caractère effectivement spatio-temporel des phénomènes physiques et illustré les consé-quences de cette correction pour le cas des mesures de grandeurs scalaires à partir de l'exemple de la pression acoustique. Dans cet article, on commence p...

Dans cet article, on commence par expliquer pourquoi les définitions classiques des paquets d’ondes posent problème. On propose ensuite une correction des définitions des paquets d’ondes tenant compte de la nature spatio-temporelle des phénomènes et de la dimension 2 à 4 des transformées de Fourier nécessaires pour synthétiser correctement ces phén...

Dans ce texte, on propose d’expliquer pourquoi il semble intéressant de substituer la notion d’écoulements acoustiques à celles d’ondes acoustiques pour le cas de la propagation en champ libre, loin de toute source. S’agissant de la pression, de la masse volumique, ou de la température dans le cadre de l’hypothèse des gaz parfaits, on montre que si...

To understand chromatical playing on a diatonic harmonica one must consider both the instrument and the musician. For each of the harmonica holes, two reeds share a single reed chamber and, theoretically, there is one reed for each direction of airflow (blown or drawn note) while both reeds practically contribute to escaping airflow. The airflow mo...

To understand (free) reed(s) oscillations, a minimal acoustical load must be introduced between the excitation and the reed(s). Classically, the model for this load is either an acoustic admittance/impedance or a reflexion function. But with an existing acoustical flow as found within some experiments, the whole model should better use nonlinear ac...

Classical methods for measurements and analysis in Musical Acoustics (and also Acoustics) rely on Fourier transforms, linear excitation superposition assumption, and monochromatic excitation or noise equivalents. It is shown that classical methods using measurements at a single point (input impedance measurement, for instance) may not be physically...

Free reedmodel used is based on a precise description of flow passing throw, the section defined between the shallot and the bended reed, and on the modelling of reed as a clamped‐free cantilever beam. Classical description of loading pipe is based on wave reflection function, not designed to be excited by a flow but backward‐ and forward‐traveling...

The study of evolutions of vacuum definitions and physical theories underline the fact that they are strongly correlated. In this article, we first explain why waves do not have any physical sense and the related consequences for speed of waves. Second, we show a determinist derivation of the Schrödinger equation, that the definitions of waves pack...

Using the example of a short pipe loaded by a free reed located upwards, we will underline the fact that a reflection function based modeling will not give the same results (and synthesized sounds) as an unsteady incompressible and lossless Bernoulli description while this model is commonly assumed to be a low-frequency limit case of the first one,...

Measurements of the inner and outer over-pressure for a diatonic harmonica were performed during blown, drawn, and bend notes notably. Using an energy analysis based on a nonregular spectral decomposition of the energy with only 10 frequency subbands, the IDS analysis, we have compared the relative weights of each subbands for both inner and outer...

We present an alternative temporal approach for convolution, providing a new algorithm, called the taches- algorithm. Based on interferences between the successive delayed and amplified output signals associated respectively with the impulses constituting the input signal, the taches-algorithm can give access immediately to the new output sample an...

En période trouble, les usages pédagogiques changent radicalement. Le découpage est l’une des pratiques qui se répandent de plus en plus dans le cadre des processus d’assimilation des savoirs et savoir-faire, toujours enseignés par cette “ caste” quelque peu surannée que nos élites s’attellent à dépecer – en enseignants, enseignants-chercheurs ou c...

IDS is a perception based subband analysis, reducing information to a limited number of relative weights describing the global spectral balance, which can unmask perceptive relevant phenomena. IDS permit listening of either a chosen partial or total re-synthesis of audio signals or scenes without introduction of perceptible analysis distortion. Wit...

Experiments studying mainly proximity effect are presented. Pink noise and music were used as stimuli and a combo guitar amplifier as source to test several microphones: omnidirectional and directional. We plot in-axis levels and spectral balances as functions of x, the distance to the source. Proximity effect was found for omnidirectional micropho...

In this paper we propose a minimal model for free reeds taking into account the significant phenomena. This free reed model may be used to build models of free reed instruments which permit numerical simulations. Several definitions for the section by which the airflow passes through the reed are reviewed and a new one is proposed which takes into...

We will present a first step in design of a broadband physical model for microphones. Within the proposed model, classical directivity patterns (omnidirectional, bidirectional and cardioids familly) are refound as limit cases: monochromatic excitation, low frequency and far-field approximation. Monophonic pieces of music are used as sources for the...

Audio scene cartography for real or simulated stereo recordings is presented. This audio scene analysis is performed doing successively: a perceptive 10-subbands analysis, calculation of temporal laws for relative delays and gains between both channels of each subband using a short-time constant scene assumption and channels inter-correlation which...

Analysis tools used in research laboratories, for sound synthesis, by musicians or sound engineers can be rather different. Discussion of the assumptions and of the limitations of these tools permits to propose a first tool as relevant and versatile as possible for all the sound actors with a major aim: one must be able to listen to each element of...

La définition de l'Acoustique repose sur te principe de propagation d'ondes. En utilisant ce principe, de nombreux résultats intéressants peuvent être trouvés mais il subsiste des résultats expérimentaux qui ne sont toujours pas expliqués par la propagation d'ondes. En reconsidérant les origines de l'Acoustique, nous proposons un principe plus géné...

Experiments have shown that free reed motion is sinusoidal and can then be described by the reed tip displacement. Taking into account the local rotation of transverse sections, an efficient ex- pression for the section by which air escapes from the instrument will be derived; an escape area which does not predict any closure discontinuity. Using a...

Chromatical playing on diatonic harmonica can be explained and reproduced using a temporal model. This model features a nonlinear vocal track, two free reeds and interaction of these three elements. The agreement between numerical simulations and experiment will be illustrated. From these results, and considering the sinusoidal reed motion during n...

One can play chromatically on a diatonic harmonica by using different playing modes: normal playing, bends and overnotes (overblows and overdraws). For each playing mode, the reed motions were measured with strain gauges and the inner pressures were recorded at the same time with a differential pressure transducer. The reed motions were shown to be...