Modelling of voiced sounds production using a modified two-mass model

The two-mass model is very often presented as a simple but efficient model quite well adapted for the purpose of voiced sounds numerical simulation. It appear however that the description of the flow through the glottis is usually oversimplified. To some extent this point could explain the limits of the model. This paper proposes a more precise description of the flow through the glottis. In particular a quasi-steady moving flow separation point is introduced. A validation of the theory under unsteady-flow conditions is presented here. The importance of the revised flow model for phonation modelling is evaluated and discussed using a simple model for the vocal cords based on the well-known two-mass model

ANALYSE DES SIGNAUX DE RONFLEMENT

Le ronflement est un phénomène dont les conséquences portent à la fois sur le confort de l'entourage et sur la santé du patient. L'analyse du signal acoustique du ronflement peut révéler certains troubles cliniques. Une étude de ce signal et quelques résultats préliminaires sont présentés.Snoring is a phenomenon which may disturb both the social life and health of a patient. Acoustical analysis of snoring can be use to identify some clinical problems and we present a study of this and some preliminary results

Exact analog of the Hatano-Nelson model in one-dimensional continuous nonreciprocal systems

Non-Hermitian topology offers a promising avenue toward an enhanced control of waves, and many of the underlying interesting phenomena are studied through the paradigmatic Hatano-Nelson (HN) model, which remains unexplored in continuous wave systems. Herein, we propose a framework to map one-dimensional continuous nonreciprocal systems onto the HN model. Our approach, based on the properties of transfer matrices, is applicable across various physical domains. We experimentally apply our method in audible acoustics using active elements, where we not only observe the predicted skin effect but also access the spectrum topology using stable configurations and observe its subsequent boundary sensitivity. By establishing a connection between continuous wave systems and the discrete HN model, our results significantly broaden the potential application of nonreciprocal topological phenomena

An acoustic criterion for the whistling of orifices in pipes

Whistling due to vortex shedding has been extensively studied in the case of cylinders in cross-flows, of flow separation above cavities and of shear layers with flow impingement feedback. Less attention has been given to pressure drop devices in piping systems, which are known to generate high noise levels due to single tones in gas systems, and even in water systems. Based on recent work of Auregan et Starobinski (1999), an experimental criterion is proposed to evaluate the whistling ability of a pressure drop device in the presence of plane waves acoustic feedback. The idea of the criterion can be summarized as follows: if for a given combination of incident pressure waves, the amount of acoustic power scattered is higher than the incident one, the pressure drop device behaves as an acoustic amplifier, so that whistling can occur if the adequate acoustic boundary conditions are met. The main advantage of this criterion is that it depends only on the acoustic scattering matrix of the device, rather than on the acoustics of the surrounding pipe. Results obtained in an air test rig with an inner diameter of 3 cm, a Mach number varying from 10−3 to 10−1 and a Reynolds number varying from 103 to 105 are reported for single hole orifices. Basing the Strouhal number on the thickness of the orifice and on the average velocity through the hole, thin single hole orifices with sharp angles appear to whistle at Strouhal numbers close to 0.2. Furthermore, it is shown that a thin orifice with a downstream bevel is prone to whistling, whereas the same orifice with the bevel upstream cannot whistle

Physical Modeling of Airflow-Walls Interactions to Understand the Sleep Apnea Syndrome

Sleep Apnea Syndrome (SAS) is defined as a partial or total closure of the patient upper airways during sleep. The term “collapsus” (or collapse) is used to describe this closure. From a fluid mechanical point of view, this collapse can be understood as a spectacular example of fluid-walls interaction. Indeed, the upper airways are delimited in their largest part by soft tissues having different geometrical and mechanical properties: velum, tongue and pharyngeal walls. Airway closure during SAS comes from the interaction between these soft tissues and the inspiratory flow. The aim of this work is to understand the physical phenomena at the origin of the collapsus and the metamorphosis in inspiratory flow pattern that has been reported during SAS. Indeed, a full comprehension of the physical conditions allowing this phenomenon is a prerequisite to be able to help in the planning of the surgical gesture that can be prescribed for the patients. The work presented here focuses on a simple model of fluid-walls interactions. The equations governing the airflow inside a constriction are coupled with a Finite Element (FE) biomechanical model of the velum. The geometries of this model is extracted from a single midsagittal radiography of a patient. The velar deformations induced by airflow interactions are computed, presented, discussed and compared to measurements collected onto an experimental setup

Extended Injection Intervals after Switching from Ranibizumab to Aflibercept in Macular Edema due to Central Retinal Vein Occlusion

Purpose. To assess treatment interval extension after switching from ranibizumab to aflibercept intravitreal injections in macular edema (ME) due to central retinal vein occlusion (CRVO) with an insufficient response or frequent recurrences to initial treatment. Methods. CRVO eyes treated with ranibizumab injections on a treat-and-extend (TAE) basis with an insufficient response or frequent recurrences were switched to aflibercept. Primary endpoint was the change in injection intervals before and after the switch. Results. Eleven eyes were included in this retrospective bicentric study. Before switching, patients received a mean number of 15.3 ranibizumab injections (range, 6–34) during a mean follow-up of 23.4 months (range, 6–57). After switching to aflibercept, patients received a mean number of 12.4 injections (range, 6–20) during a mean follow-up of 25.5 months (range, 16–38). Treatment interval could be extended from 6.1 (range, 4–8) to 11 weeks (range, 8–16) (p=0.001) corresponding to a mean extension of injection interval of +4.9 weeks. Conclusion. In case of insufficient response or frequent recurrences of ME due to CRVO in patients treated with ranibizumab on a TAE basis, switching to aflibercept could allow extending treatment intervals, which could reduce the injection burden for these patients

Comportement des materiaux absorbants dans les champs acoustiques intenses

Available from INIST (FR), Document Supply Service, under shelf-number : RP 185 (4291) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEMinistere de l'Amenagement du Territoire et de l'Environnement, 75 - Paris (France). Service de la Recherche et des Affaires Economiques (SRAE)FRFranc