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April 2015 - present
Publications
Publications (126)
Ship machinery generates significant noise levels, mainly including energetic and low-frequency tonal components , posing two issues. The first is linked to potential health and safety problems related to onboard noise, mainly for the crew working in the engine room. The second concern is that the underwater noise generated by machinery can harm ma...
With ships operating in areas including important marine biodiversity, it is crucial to understand the sources and characteristics of underwater noise and develop effective measures to mitigate underwater noise's impact on the environment. The underwater noise signature from a ship is usually dominated by machinery noise and propulsion engines at l...
This work is grounded on the force analysis technique, an identification method that directly uses a structure's equation of motion to formulate an inverse problem, explicitly identifying the force causing the system's motion. This technique has mainly been applied on heavy objects since contact vibration measurements using accelerometers on light...
We present the Sherbrooke-Lyon Research Training Program in Acoustics ("Projet Samuel de Champlain" 2022-2024, funded by the FRQNT: Fonds de recherche du Québec - Nature et technologies), which brings together teams from Université de Sherbrooke and from Master of Science in Acoustics of Lyon. This project aims to build a joint teaching program in...
Stiffened structures excited by a turbulent boundary layer (TBL) occur in many engineering applications, particularly in the aerospace and naval sectors. The structures encountered in these applications are generally large and complex, and carrying out experiments in order to characterize their vibration response can be costly, time-consuming and d...
Urban sprawl brings cities closer to natural areas, making them cohabit is a significant environmental challenge. Densification can also increase light and noise pollution, negatively affecting human and biodiversity well-being. Grounded on a collaboration between a college and a university, this work combines brightness and noise maps to establish...
Underwater radiated noise (URN) from commercial shipping is partly responsible for increased ocean ambient noise levels in the last decades. To preserve marine wildlife, there is a need to reduce it. Machinery noise is the dominant URN source at lower speeds. Mitigation technologies exist to reduce it, but a lack of quantitative data regarding thei...
Stiffened structures excited by a turbulent boundary layer (TBL) occur in many engineering applications, particularly in the aerospace and naval sectors. The structures encountered in these applications are generally large and complex, and carrying out experiments in order to characterize their vibration response can be costly, time-consuming and d...
This vibroacoustic research project involves two laboratories specializing in mechanical engineering in Canada (Université de Sherbrooke) and Chile (Universidad de Chile).
The project aims to design and characterize structures with improved acoustic or vibration insulation performance while using less material than conventional soundproofing mate...
Traditional methods for generating band gaps in beams usually involve adding periodic elements like tuned mass dampers or masses, or applying complex geometrical changes. This research suggests a subtraction-based method achieved by removing material in the thickness direction through straightforward machining operations, thus forming periodic cell...
In 1964, Robert Bruce Lindsay introduced “The Science of Acoustics,” a graphical representation that has become popular and is often called the Wheel of Acoustics. This communication first recalls the historical context and initial versions of this representation. Adaptations to its original design are then introduced. Some follow the idea of a whe...
The study focuses on the design of an acoustic liner to tackle noise from modern turbofan engines, particularly addressing broadband components. Introducing innovative locally-reacting liner designs based on coiled quarter wavelength tubes, the research compares three proposed models (B, C, D) with a conventional liner (A) available in literature....
A technique for estimating the sound absorption of materials under oblique incidence plane wave and diffuse field excitations is proposed. It requires a mobile loudspeaker and a pair of fixed microphones above a layer of absorbing material. Starting from sound pressure measurements made above the material surface for multiple source positions and b...
This work is grounded on the force analysis technique, an identification method that directly uses a structure's equation of motion to formulate an inverse problem, explicitly identifying the force causing the structure's motion. Prior research employing this technique has been predominantly conducted in the frequency domain and was limited to stat...
This communication proposes a basis for offering short introductions to the basic principles in acoustics, like adding decibels and the behavior of Helmholtz or quarter-wavelength resonators. The proposed approach combine mobile and experiential learning approaches using smartphone sensors and applications. The objective of these mobile laboratorie...
Reducing underwater noise pollution from ship machinery is a significant challenge. Ship machinery usually operates at fixed speeds and emits tonal noise with large amplitudes at low frequencies. Conventional soundproofing materials are inadequate for absorbing tonal noise and require large thicknesses at low frequencies. Quarter-wavelength resonat...
It's often difficult for the general public and young people to grasp the importance of acoustics in everyday life and its many branches and fields of application. However, it's equally complex for people working or studying acoustics to communicate to this audience while avoiding the same focus on detail as scientific publications. Science communi...
Ocean ambient levels have increased in the last decades, especially in the low-frequency domain (under 500 Hz). This increase is partly due to underwater radiated noise (URN) from commercial ships. Excessive URN harms marine life and is, therefore, considered a pollution that needs to be reduced. At low speeds, machinery is the primary noise source...
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 pr...
Anthropogenic noise from navigation is a major contributor to the disturbance of the acoustic soundscape in underwater environments. The noise generated by ship’s machinery exhibits energetic tonal harmonic peaks at multiples of the rotating and firing frequency, that occur in the 20-200 Hz frequency range and difficult to control with classical so...
Acoustic resonators like Helmholtz resonators, micro-perforated panels and quarter wavelength tubes are employed to suppress tonal noise for several industry application. The issue related to the design of these resonators is their bulkiness for low-frequency application and their narrow band behaviour. In this paper, microperforated panels and coi...
Micro-perforated panel sound absorbers are widely used in noise control applications in the fields of architectural acoustics and transport acoustics. Combining micro-perforated panels with other resonant or sound absorbing systems may broaden the frequency range in which they absorb sound while ensuring that large sound absorption values are reach...
A dummy head is a tool used to generate binaural recordings, i.e. recordings when listened to through headphones that allow for the listener to hear from the dummy’s perspective. A dummy head typically includes pinnae and ear canals in which microphones are placed. The global shape of a dummy head replicates an average-sized human head, and variati...
The main scope of this work is to study the effect of embedding a periodic pattern inside a porous material, in order to passively improving its acoustic performance in terms of sound transmission loss. A contemplated application is the improvement of classical aeronautical soundproofing packages. In order to reach this goal, numerical models of an...
To reduce their space requirement, quarter wavelength resonators are coiled up into a spiral to have the shape of a flat cylinder. The practical implementation of these resonators is tested using 3D printing, laser cutting and machining. Numerical simulations and impedance tube measurements are first compared for a normally incident plane wave exci...
A method for measuring the diffuse field sound absorption coefficient of a material using sound field synthesis is proposed. A planar loudspeaker array is first used to generate acoustic plane waves with variable incidence angle on the surface of a material under test. Using a two-microphone probe positioned closely to the sample’s surface, the ang...
To evaluate the respective effect of microphone and dummy head morphology on the head-related transfer functions (HRTFs), measurements were performed in an anechoic room for two different dummy heads and their associated pair of microphones. Four different configurations are considered : (i) head 1 with microphones 1, (ii) head 2 with microphones 1...
Digital image correlation, deflectometry and digital holography are some of the full-field optical measurement techniques that have matured in recent years. Their use in vibroacoustic applications is gaining attention and there is a need for cataloging their performance in order to provide, to a broad community of users and potential future users,...
Standardized methods for measuring sound absorption such as the impedance tube and reverberation chamber methods are limited to normal or diffuse incidence, respectively. Two research axes have been generally followed in the literature to develop alternative techniques, the first one focusing on the measurement part, that is from the two-microphone...
Acoustics is generally defined as the science that deals with the production, transmission, and reception of sound and the understanding and control of its effects. In fact, the fields of acoustics cover an especially broad range of subjects and domains, and comprehensive acoustics textbooks are usually quite thick as a consequence. While they are...
Comics and manga have long been seen as childish literature, even if sometimes referred to as an art. Webpages discussing matters like Mathematics or Science are usually considered popularized content and not as tools with which research can be built. Arcade video games are often not considered serious games that can be used for learning or team bu...
Les méthodes normalisées de mesure de l'absorption acoustique sont limitées à une incidence normale ou diffuse. Elles sont également connues pour leur manque de flexibilité, de précision aux basses fréquences et pour leur tendance à produire des résultats non physiques (valeur du coefficient d'absorption supérieure à 1). Alors qu'une partie des mét...
As an alternative to laboratory controlled listening tests, a crowd sourced approach was tested using an audio polling station installed in a sound-related exhibition. Among other subjects, visitors were asked to provide their opinion concerning sound quality of vehicles and sound quality of audio coding algorithms. Using the same data set, another...
Engineered wood constructions and timber buildings are rapidly developing, while the numerical techniques usable for their sound insulation properties are various and often still under development. This research constitutes a first step towards the reliability determination of building acoustics simulations on timber-based elements. A small scale r...
Deflectometry is a full-field optical technique for surface slope measurement based on recording the deformation of a grid image. A hybrid method is explored in which the grid images from a deflectometry measurement are processed using a particle image velocimetry analysis tool. The hybrid approach is compared to a common phase shifting algorithm f...
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ABSTRACT
In our modern and highly connected world, we are fed with large and growing amounts of information. As an example, the yearly number of published scientific articles exceeded the astounding number of 1 500 000 papers.in 2015. More and more time is spent on numerical media or supports, with texts that tend to be scanned rat...
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ABSTRACT
While having been the object of various criticisms and considered to be a childish litterature for a long time, comics are now a legitimate art form, the ninth art. Comics are also considered as a fully fledged tool for disseminating and explaining science. More and more researchers advocate for a larger use of comics in s...
Data visualisation and visual storytelling are increasingly common terms when institutions and scientists want to introduce people to their research and science through stories. Yet institutions mostly teach and train their scientists in the language of science and scientific journals, whereas research dissemination calls for other forms of communi...
This paper reports results of full field vibration measurements conducted on a laboratory test case, a cantilever beam, submitted to a transient excitation using an impact hammer. The deflectometry technique in the visible and in the infrared spectra are employed to measure the beam’s vibration field using high-speed cameras. The respective perform...
The experimental study of a structure’s response to a turbulent boundary layer (TBL) excitation using wind-tunnel or in-vehicle testing generally requires considerable efforts, including the measurement of both turbulent wall-pressure fluctuations and the structure’s vibration response. As an alternative method to highly demanding testing procedure...
A hybrid uncorrelated wall plane wave (UWPW) and finite element method (FEM) technique is introduced to the predict vibroacoustic response of a panel under turbulent boundary layer (TBL) excitation. The spectrum of the wall pressure fluctuations is evaluated from the TBL parameters and by using semi-empirical models from literature. TBL parameters...
A successful application of statistical energy analysis for analyzing energy exchanges between weakly coupled subsystems theoretically requires a diffuse vibrational field in all subsystems. So as to verify the conditions of establishment of diffuse field in practice, full-field vibration measurements were conducted with a high speed camera on a si...
Similitude laws in vibro-acoustics are potentially interesting to extrapolate measurements performed on small structures to the response of larger structures. This paper examines similitude laws for the vibroacoustic response of flat orthotropic flexural rectangular panels radiating sound in a semi-infinite light fluid medium. The scaling parameter...
Listening tests are used in various sound-related research areas. Such tests generally require complex and controlled protocols that involve consequent manpower, demanding preparation and a limited number of participants. Furthermore, big data analytics can hardly be applied using such data gathering schemes. Several options exist to overcome such...
In structural dynamics, similitude laws usually deal with simple configurations as thin flat plates with point forces. Only recently, few papers have analyzed stiffened shells or stochastic pressure loads.
This research activity extends the applicability of some similitude laws, developed for thin flat plates under a turbulent boundary layer load,...
The vibroacoustic responses of a simply supported panel excited by turbulent flow are analytically and numerically investigated. In the analytical model, the radiated sound power is described in terms of the cross spectrum density of the wall pressure field and sensitivity functions for the acoustic pressure and fluid particle velocity. For the num...
This paper reports results of laboratory and field tests of a tonal and a broadband backup alarms. One-, two- and three-dimensional sound pressure measurements were first conducted in a hemi-anechoic room and in a reverberant room. For the hemi-anechoic room condition, the additional effect of an absorptive or reflective ground condition was studie...
An acoustic imaging algorithm is proposed herein for transient noise source time reconstruction. Time domain formulations are not well suited for acoustic imaging because of the size of the resulting system to be inversed. Based on the phase coherence principle widely used in ultrasound imaging and image processing, the first step of the algorithm...
This communication investigates exact and distorted similitudes and the related scaling laws for the analysis of both dynamic response and radiated power of rectangular plates. The response of a given panel in similitude from another one is determined from a generalization of the modal approach, allowing the use of mode shapes, natural frequencies...
In this work, a hybrid numerical approach to predict the vibrational responses of planar structures excited by a turbulent boundary layer is presented. The approach combines an uncorrelated wall plane wave technique with the finite element method. The wall pressure field induced by a turbulent boundary layer is obtained as a set of uncorrelated wal...
The characterization of vibroacoustic sources using microphone arrays in the time domain is still challenging because of the bad conditioning and extensive computational resources required to solve the associated ill-posed problem. The Near-field Acoustical Holography (NAH) framework and the Time-Reversal techniques are among the approaches propose...
This paper investigates and compares three methods for the identification of the flexural wavenumbers in thin laminated wood panels. Laboratory measurements are performed on a plywood panel, an inhomogeneous and orthotropic plate, and the propagation characteristics of flexural waves are characterized along five radial directions. The methods consi...
The general context of this study is to perform cross-validation of analytical and numerical calculations of vibroacoustic response of panels under a turbulent boundary layer excitation. This article focuses on the specific case of a rectangular aluminum panel with controlled simply-supported boundary conditions, and tested in a lowspeed anechoic w...
This article reports numerical and experimental results concerning the estimation of the diffuse field sound absorption coefficient of several different materials under a synthetized diffuse acoustic field excitation in laboratory and in situ conditions. The proposed measurement method is based on a sound field reproduction approach and a synthetic...
The sound transmission loss of complex curved aircraft panels under diffuse acoustic field excitation is experimentally and numerically studied. Two different aircraft sidewall panels are considered: a thick composite sandwich panel and a thin aluminium panel with stiffening elements (stringers and frames). Both bare configuration and with attached...
Similitude laws for scaling the vibration response of flat panels to a turbulent boundary
layer excitation are proposed and analyzed in this paper. Their relevance is studied from
an analytical, experimental and numerical perspective. It is first shown that a perfect similitude, in terms of vibration response scaling, can theoretically be achieved...
Using the classical two-microphone approach and a source-image model, this paper investigates the possibility of measuring sound reflection in two specific cases using a directional transducer instead of a classical loudspeaker or a point source (monopole). A first experiment aims at measuring the sound absorption of three materials at normal incid...
The identification of dynamic loads acting on structures is a key aspect of several engineering domains involving structure-borne sound and vibration problems, stress analysis, or even the study of fatigue-induced structural damages. This work is concerned with the reconstruction of localized transient and distributed random excitations on plates a...
An important dip in the sound transmission loss of curved panels occurs at the ring frequency. The relevance of using small-scale resonators to solve this issue is experimentally demonstrated on an aircraft sidewall panel. The effect of varying the spatial distribution of single frequency resonators (including combination with a broadband soundproo...
This paper aims at identifying random excitations acting on thin, plane structures from their measured vibration response. For random pressure fields such as the diffuse acoustic field (DAF) and turbulent boundary layer (TBL), two quantities of interest are to be determined, namely the wall pressure auto-spectral and cross-spectral density function...
This study aims at developing an experimental method for characterizing the vibro-acoustic behavior of panels excited by random pressure fields. Although the method would be theoretically applicable to any stationary in time and spatially homogeneous random process, and for points belonging to the acoustic medium or to the panel, the turbulent boun...
Similitude laws for the vibration response of simply supported plates under random excitations are derived and tested numerically and experimentally for the case of a turbulent boundary layer. Analytical calculations show that under the assumption of proportional sides, perfect similitude in terms of vibration response scaling can be achieved betwe...
Le résumé et le rapport final de cette activité peuvent être obtenus sur le site de l'IRSST (Institut de recherche Robert-Sauvé en santé et en Sécurité du travail) à l'adresse suivante:
http://www.irsst.qc.ca/publications-et-outils/publication/i/101005/n/caracterisation-materiaux-acoustiques
This presentation will present the ongoing setup of a general audience exhibition dedicated to acoustics in Sherbrooke, Québec. This project is built up with the Sherbrooke Nature and Science museum, Sherbrooke University (faculty and research groups) and with the contribution of external structures (like the Canadian acoustical association and com...
Tonal reversing alarms are a recognized source of noise annoyance and recent broadband alarms target a reduction of the environmental impact of backup sound alarms. From the worker and safety point, the sound field generated behind vehicles by broadband alarms is considered more uniform and its source easier to localize in space, a main drawback of...
The ability of photographic techniques to quickly record high volumes of scientific data has been understood since the early 1900s. It is only following the advent of digital imaging and data processing systems that so-called full-field optical measurement techniques became sufficiently reliable for performing high spatial density structural vibrat...
Recent work has shown that the Poisson’s ratio of an isotropic material can be determined using the anticlastic curvature that exists in certain mode shapes of a free, rectangular panel of that material. The shapes must be measured experimentally in order to determine the curvature that exists. The curvature is then related to Poisson’s ratio based...
Compared to numerous theoretical studies, the problem of experimentally realizing supported conditions on plane panels has received very little attention. A technique to setup a simply supported rectangular plane panel for laboratory vibroacoustic tests is described. Several application cases are reported, including three panels built in Groupe d’A...
Compared with a uniform porous layer, arranging a poroelastic material following a lamella network structure provides additional sound absorption below the quarter wavelength resonance frequency, i.e. in the low frequency domain. The mechanisms involved in this additional sound absorption are highlighted by a numerical approach that incorporates ge...
The sound transmission loss of a homogeneous, isotropic, thin panel under a diffuse acoustic field excitation is derived from a measurement of its airborne induced vibration field. Using this single dataset, the virtual fields method allows identifying the wall pressure field exciting the panel and estimating the corresponding incident acoustic pow...
This study aims at validating an experimental method for characterizing the vibration behavior of panels excited by a turbulent boundary layer (TBL) excitation as a possible alternative to standard means like wind tunnels or in situ tests. The approach takes advantage of an explicit separation of the excitation contribution from the dynamic behavio...