Acoustics, Dynamics, and Controls Commons^™

Reliability Of An Extended Version Of The 3m™ Eargage Tool To Assess Earcanal Size And Assist Earplug Selection, Bastien Poissenot-Arrigoni, Laurence Martin, Alessia Negrini, Djamal Berbiche, Olivier Doutres, Franck Sgard

Études primaires

Objective: Evaluate the ability of an extended version of the 3 MTM Eargage to estimate the earcanal size and assess the likelihood that a particular earplug can fit an individual’s earcanal, ultimately serving as a tool for selecting earplugs in the field. Design: Earcanal morphology, assessed through earcanal earmolds scans, is compared to earcanal size assessed with the extended eargage (EE) via box plots and Pearson linear correlations coefficients. Relations between attenuation measured on participants (for 6 different earplugs) and their earcanal size assessed with the EE are established via comparison tests. Study sample: 121 participants exposed to occupational noise …

On The Use Of The Local Reflection Coefficient To Assess The Diffuse Field Sound Absorption Coefficient Of A Porous Material, Franck Sgard, Noureddine Atalla, Olivier Robin

Études primaires

The diffuse field sound absorption coefficient (SAC) of a sound absorber can be obtained from an average over the incidence angles of the oblique incidence plane wave SAC. The plane wave SAC can be derived from the plane wave complex-valued reflection coefficient defined as the ratio of the reflected sound pressure at a given point on the material surface to the incident sound pressure at the same point. In practice, the material is excited by a monopole, and the reflection coefficient becomes a local quantity which is a function of the source height and the radial distance from the source. …

An Impedance Tube Technique For Estimating The Insertion Loss Of Earplugs, K. Carillo, O. Doutres, F. Sgard

Études primaires

This paper proposes a quick and straightforward technique for estimating the insertion loss (IL) of earplugs measured on an acoustical test fixture (ATF) using a commercial impedance tube. In this method, the earplug's acoustic properties (i.e., its transmission loss and the reflection coefficient of its medial surface) are determined from its transfer matrix measured using the three-microphones impedance tube method modified here for the current application. The IL is then estimated using a one-dimensional analytical model of open and occluded earcanals based on the wavefield decomposition theory. The method is evaluated numerically and experimentally from 50 Hz to 6.5 kHz. …

On The Area-Averaged Effective Sound Absorption Coefficient Of Porous Materials Excited By A Monopole, Franck Sgard, Noureddine Atalla, Olivier Robin, Alain Berry

Études primaires

The area-averaged effective sound absorption coefficient (SAC) of a rigid-backed homogeneous porous material subjected to a monopole excitation is calculated as the absorbed-to-incident sound power ratio. Using Allard's model to describe the sound propagation above the porous material, an analytical model for this power-based SAC is proposed and proves to give a good approximation of the sound absorption performance under monopole excitation of sufficiently large areas of material. The impact of factors on the power-based SAC, such as monopole height, material radial dimension used to calculate the sound powers, and material properties is discussed. The power-based SAC frequency-dependent behavior is …

Measurement Of The Local Static Mechanical Pressure Of Earplugs, Luiz G.C. Melo, Ahmed S. Dalaq, Franck Sgard, Olivier Doutres, Laurianne Legroux, Eric Wagnac

Études primaires

Earplugs are used in various critical industrial sectors, such as construction, aviation, military and defense, transportation, and healthcare. However, they present inherent drawbacks, notably discomfort that can lead to inconsistent and incorrect use, thereby leaving a significant proportion of workers vulnerable to irreversible hearing damage, ranging from tinnitus to deafness. This discomfort is closely linked to a physical parameter known as static mechanical pressure (SMP), representing the pressure exerted by earplugs on the earcanal walls. Determining the SMP is crucial for developing earplugs that prioritize comfort. However, experimental studies in this area are scarce and there is no experimental set-up …

Développement D’Un Système De Mesure Pour La Caractérisation Des Traitements Absorbants En Laboratoire, Alain Berry, Olivier Robin, Thomas Dupont, Franck Sgard

Rapports de recherche scientifique

Le bruit constitue une préoccupation de plus en plus importante et généralisée dans le monde. Selon l’Organisation mondiale de la Santé, environ une personne sur quatre dans le monde souffrira de déficience auditive à des degrés divers d’ici à 2050. Dans de nombreux pays et régions du globe, le bruit représente le second facteur environnemental provoquant le plus de dommages sanitaires, et ce derrière la pollution atmosphérique. Sur un volet cognitif ou perceptif, le bruit environnemental peut par exemple perturber le sommeil et gêner l’apprentissage en milieu scolaire. Dans un milieu de travail, il peut perturber la bonne compréhension/perception de …

Passive Earplug Including Helmholtz Resonators Arranged In Series To Achieve Broadband Near Zero Occlusion Effect At Low Frequencies, Kevin Carillo, Franck Sgard, Olivier Dazel, Olivier Doutres

Études primaires

The use of passive earplugs is often associated with the occlusion effect: a phenomenon described as the increased auditory perception of one's own physiological noise at low frequencies. As a notable acoustic discomfort, the occlusion effect penalizes the use and the efficiency of earplugs. This phenomenon is objectively characterized by the increase in sound pressure level in the occluded ear canal compared to the open ear canal. Taking inspiration from acoustic metamaterials, a new design of a three-dimensional printed “meta-earplug,” made of four Helmholtz resonators arranged in series, is proposed for achieving near zero objective occlusion effect measured on artificial …

Pressure Induced By Roll-Down Foam-Earplugs On Earcanal, Ahmed Dalaq, Luiz Melo, Franck Sgard, Olivier Doutres, Éric Wagnac

Études primaires

Physical discomfort of earplug is a common complaint, so much so it jeopardizes the health and safety of workers, resulting in frequent noncompliance to proper wearing of earplugs. A pressing need thus arises to understand the underlying mechanics for the interaction of earplugs with earcanal walls. An idealized cylindrical geometry of earcanal is first treated with computational and analytical modeling to predict the pressure induced by roll-down cylindrical PVC foam earplugs. In order to predict representative pressure values and distribution, we estimated the hyperelastic properties of foam-based earplugs and characterized their behavior using a stent testing machine (J-Crimp^TM machine) …

Développement D'Une Méthode De Mesure De L'Exposition Sonore Effective Intraauriculaire Pour Une Utilisation En Milieu De Travail, Hugues Nélisse, Fabien Bonnet, Marcos Nogarolli, Jérémie Voix

Rapports de recherche scientifique

De nombreux travailleurs sont exposés quotidiennement à des niveaux de bruit susceptibles d'endommager leur audition. De ce fait, la mesure de l'exposition sonore est essentielle afin d'identifier et d’évaluer des solutions correctives pour protéger adéquatement les travailleurs. Cependant, les méthodes et les technologies de mesure actuelles ne permettent généralement pas de déterminer avec précision l'exposition au bruit subie par un individu sur son lieu de travail. La dosimétrie intraauriculaire est une solution prometteuse pour pallier un certain nombre de problèmes liés aux méthodes de mesure conventionnelles, mais cette méthodologie est fragilisée de trois façons : 1) l'exposition sonore mesurée dans …

Étude De L’Applicabilité De Haut-Parleurs Paramétriques Au Développement De Nouveaux Concepts D’Alarmes De Recul, Olivier Robin, Alain Berry, Hugues Nélisse

Rapports de recherche scientifique

L’utilisation d’alarmes de recul est obligatoire sur une majorité de véhicules lourds et reste un moyen largement utilisé pour prévenir et alerter les personnes œuvrant à proximité de ces véhicules. Des études antérieures, réalisées par l’IRSST, ont montré les limites d’efficacité des alarmes utilisées en milieu de travail pour minimiser le risque à la sécurité des travailleurs. De plus, les alarmes de recul, par le son de niveau élevé et très typé qu’elles produisent, sont régulièrement une source de nuisance importante pour les travailleurs, et aussi pour les riverains. Ces problèmes de gêne et de perception sonore pour les travailleurs …

Mise Au Point D’Une Méthode De Mesure Objective De L’Effet D’Occlusion Basée Sur La Voix, Hugues Nélisse, Hugo Saint-Gaudens, Franck Sgard, Olivier Doutres

Rapports de recherche scientifique

Lors de l’utilisation de protecteurs auditifs ou de prothèses auditives, le fait d’obstruer le canal auditif peut engendrer un effet indésirable et désagréable, appelé « effet d’occlusion », qui se manifeste notamment par la sensation que notre propre voix sonne différemment, avec de basses fréquences amplifiées, qu’elle est distordue. L’effet d’occlusion est souvent considéré comme une source d’inconfort qui entraîne parfois les utilisateurs de protecteurs ou de prothèses à mal les utiliser ou encore à simplement les retirer. Dans le cas des travailleurs, par exemple, le retrait des protecteurs auditifs peut les exposer à des niveaux de bruits potentiellement dangereux, …

Assessing The Comfort Of Earplugs: Development And Validation Of The French Version Of The Coprod Questionnaire, Jonathan Terroir, Nellie Perrin, Pascal Wild, Olivier Doutres, Franck Sgard, Chantal Gauvin, Alessia Negrini

Études primaires

Earplugs are a common form of protection for workers exposed to hazardous noise levels. Their comfort directly impacts the effective protection by influencing their consistent and correct use. Nevertheless, comfort definition may vary according to the studies. Thus, a previous review of the literature has shown that to improve our understanding of perceived comfort and to reduce measurement variability, it is advisable to consider comfort through a multidimensional construct (physical, acoustical, functional and psychological). On this basis, the COPROD (COnfort des PROtections auDitives/COmfort of hearing PROtection Devices) questionnaire was developed. It is intended for people working in noisy environments. Nine …

Principle Of An Acoustical Method For Estimating The Centroid Position Of The Earcanal Wall Normal Velocity Induced By Bone-Conducted Stimulation: Numerical Evaluation, Kevin Carillo, Olivier Doutres, Franck Sgard

Études primaires

The occlusion effect is commonly experienced as the altered perception of one’s own physiological noise when the earcanal entrance is blocked. Objectively, this phenomenon corresponds to an acoustic pressure increase in the occluded earcanal. The occlusion effect originates from the earcanal wall normal vibration and depends on the spatial distribution of the latter. At low frequencies, this spatial distribution can be characterized by the position of its centroid along the earcanal middle axis. This paper describes the principle of an acoustical method for estimating this centroid position at low frequencies. The proposed method consists in measuring the eardrum acoustic pressure …

Numerical Investigation Of The Earplug Contribution To The Low-Frequency Objective Occlusion Effect Induced By Bone-Conducted Stimulation, Kevin Carillo, Olivier Doutres, Franck Sgard

Études primaires

The use of earplugs is commonly associated with an increased perception of the bone-conducted part of one's own physiological noise. This phenomenon is referred to as occlusion effect and is most prominent at low frequencies. Several factors influence the occlusion effect, such as the ear anatomy; the bone-conducted stimulation; and the type of occlusion device and its fit, insertion depth, and material properties. The latter factor is of great interest to potentially reduce the occlusion effect of passive earplugs. This paper investigates the mechanism(s) of contribution of earplugs to the objective occlusion effect. A two-dimensional axi-symmetric finite element model of …

On The Removal Of The Open Earcanal High-Pass Filter Effect Due To Its Occlusion: A Bone-Conduction Occlusion Effect Theory, Kevin Carillo, Olivier Doutres, Franck Sgard

Études primaires

The occlusion effect is commonly experienced by in-ear device wearers as an increased loudness sensation of bone-conducted low frequency sounds. A widespread theory proposed by Tonndorf and based on a simplified electro-acoustic model describes the phenomenon as the removal of the open earcanal high-pass filter effect due to a perfect or partial occlusion. However, this filter has not been clearly defined and several ambiguities remain. Revisiting the model, a second order high-pass filter effect for the volume velocity transferred between the earcanal wall and the eardrum is highlighted. This filter remains for partial occlusion but vanishes for perfect occlusion. In …

Simulation Of The Objective Occlusion Effect Induced By Bone-Conducted Stimulation Using A Three-Dimensional Finite-Element Model Of A Human Head, Huiyang Xu, Franck Sgard, Kévin Carillo, Éric Wagnac, Jacques De Guise

Études primaires

The occlusion effect (OE) refers to the phenomenon that more bone-conducted physiological sounds are transmitted into the earcanal when it is blocked and may cause discomfort on users of hearing protection devices. Models have been proposed to study the OE as they can help understand the physical mechanisms and can be used to evaluate the individual contribution on the OE of the factors that may affect it (i.e., occlusion device, ear anatomy, and stimulation). The existing finite element models developed to study the OE are limited by their truncated ear geometries. In order to progress in the understanding of the …

Effect Of Hearing And Head Protection On The Localization Of Tonal And Broadband Reverse Alarms, Chantal Laroche, Christian Giguère, Véronique Vaillancourt, Claudia Marleau, Marie-France Cadieux, Karina Laprise-Girard, Emily Gula, Véronique Carroll, Manuelle Bibeau, Hugues Nélisse

Études primaires

Objective

This study explored the effects of hearing protection devices (HPDs) and head protection on the ability of normal-hearing individuals to localize reverse alarms in background noise.

Background

Among factors potentially contributing to accidents involving heavy vehicles, reverse alarms can be difficult to localize in space, leading to errors in identifying the source of danger. Previous studies have shown that traditional tonal alarms are more difficult to localize than broadband alarms. In addition, HPDs and safety helmets may further impair localization.

Method

Standing in the middle of an array of eight loudspeakers, participants with and without HPDs (passive and level-dependent) …

Theoretical Investigation Of The Low Frequency Fundamental Mechanism Of The Objective Occlusion Effect Induced By Bone-Conducted Stimulation, Kevin Carillo, Olivier Doutres, Franck Sgard

Études primaires

The objective occlusion effect induced by bone-conducted stimulation refers to the low frequency acoustic pressure increase that results from occluding the ear canal opening. This phenomenon is commonly interpreted as follows: the bone-conducted sound “leaks” through the earcanal opening and is “trapped” by the occlusion device. This instinctive interpretation misrepresents the fundamental mechanism of the occlusion effect related to the earcanal impedance increase and already highlighted by existing electro-acoustic models. However, these models simplify the earcanal wall vibration (i.e., the origin of the phenomenon) to a volume velocity source which, in the authors' opinion, (i) hinders an exhaustive comprehension of …

Conception D’Oreilles Artificielles Réalistes Dédiées À L’Étude Du Confort Acoustique Et Physique Des Protecteurs Auditifs Intra-Auriculaires, Simon Benacchio, Olivier Doutres, Éric Wagnac, Franck Sgard

Rapports de recherche scientifique

Au Québec, environ 360 000 travailleurs sont exposés quotidiennement à des niveaux de bruit susceptibles d’engendrer des problèmes d’audition. Les protecteurs auditifs individuels sont souvent utilisés pour pallier ce problème. Cependant, l’inconfort lié à l'utilisation de ces protecteurs limite la durée du port et donc l'efficacité de la protection. Le développement d'outils de conception acoustique minimisant les sources d’inconforts auditifs et physiques de ces protecteurs tout en assurant une atténuation adéquate constitue le contexte de cette recherche.

La présente étude se concentre sur deux indicateurs du confort associés au port des bouchons d’oreille : l’atténuation et l’effet d’occlusion. L’atténuation quantifie …

Procedure To Measure The Penetration Of One Mechanical Filter For Nanoparticles: Validation By Comparison, Pooya Abdolghader, Clothilde Brochot, Fariborz Haghighat, Ali Bahloul

Études primaires

Nanoparticles (NPs) are particles of less than or equal to 100 nm in diameter. Due to their size, they have a significant effect on health and safety of people. Capture of these NPs in general ventilation systems by filters remains one of the most widely used means of protection due to its relative simplicity of implementation and its effectiveness for capturing various size of particles. In North America, filters used in general ventilation systems are tested by the ANSI/ASHRAE Standard 52.2 and are graded according to their efficiency, which is a function of particle diameter. However, the current standard limits …

A Transfer Matrix Model Of The Iec 60318-4 Ear Simulator: Application To The Simulation Of Earplug Insertion Loss, Yu Luan, Franck Sgard, Simon Benacchio, Hugues Nélisse, Olivier Doutres

Études primaires

The IEC 60318-4 ear simulator is used to measure the insertion loss (IL) of earplugs in the ear canal of an acoustical test fixture (ATF) and is designed to represent an average acoustic impedance (in a reference plane) of the human ear. The ear simulator is usually modeled using a lumped parameter model (LPM) which has frequency limitations and inadequately accounts for the thermo-viscous effects in the simulator. The simulator numerical models that can better deal with the thermo-viscous phenomena often lack essential geometric details. Most related studies also suffer from the lack of experimental validation of the models. Therefore, …

An Axisymmetric Finite Element Model To Study The Earplug Contribution To The Bone Conduction Occlusion Effect, Martin K. Brummund, Franck Sgard, Yvan Petit, Frédéric Laville, Hugues Nélisse

Études primaires

An axisymmetric linear elasto-acoustic finite element (FE) model of an occluded human external ear is proposed to simulate the bone conduction occlusion effect (OE). The model consists of a cylindrical ear canal cavity surrounded by layers of biological tissues (skin, cartilage and bone) in which an earplug is inserted. Geometrical and material properties are taken from the literature. OEs are predicted for foam and silicone earplug FE-models using COMSOL Multiphysics (COMSOL®, Sweden). The FE-model is shown to predict the experimental OE measured in two healthy human reference groups wearing foam or silicone earplugs, satisfactorily. Deviations between model and experiment are …