2024-03-29T02:27:29Z
https://jcaa.caa-aca.ca/index.php/jcaa/oai
oai:jcaa.caa-aca.ca:article/2586
2014-09-18T23:33:23Z
jcaa:ART-NC
"140513 2014 eng "
2291-1391
0711-6659
dc
Geometry Effects on the Noise Reduction of Helmholtz Resonators
Mekid, Samir
King Fahd University of Petroleum and Minerals
Farooqui, M
Liu, Z
The effect of geometry shape of the Helmholtz resonator on its resonant frequency and noise attenuation capability is discussed in this paper. The theory of resonant frequency depending on the shape of the vessel of the resonator is verified analytical and numerically using COMSOL for one and two degrees of freedom resonators. The simulation was validated experimentally and has shown very good agreements. Various shapes of the resonators were compared in arrays. A better understanding of the shape effect is shown through simulations.
Canadian Acoustical Association / Association canadienne d'acoustique
2014-05-28 20:59:49
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/2586
Canadian Acoustics; Vol. 42 No. 2 (2014)
eng
Copyright (c)
oai:jcaa.caa-aca.ca:article/2600
2013-04-19T04:53:52Z
jcaa:ART-NC
2291-1391
0711-6659
dc
Noise Mapping of an Educational Environment
Zannin, Paulo Henrique Trombetta
Laboratory of Environmental and Industrial Acoustics and Acoustic Comfort,
Federal University of Paraná, Brazil
The purpose of this study was to perform computer-assisted noise mapping of an educational environment. The computer simulations were performed using SoundPLAN software. An analysis of the acoustic maps generated by the simulations indicates that contributions to the noise levels found on the campus originate mostly from three streets on campus, as well as from the roads surrounding the outer perimeter – the Green Line and the BR-277 highway. The computer-generated acoustic maps show that the noise levels within the campus exceed the limit of Leq = 50 dB(A) established for educational areas, according to the Brazilian standard for noise assessment in communities. Therefore, the noise maps indicate a critical situation of noise pollution on campus. However, despite this negative and concerning situation of noise pollution, the acoustic maps also reveal several “islands of acoustic tranquility” on campus. These “islands” can be observed adjacent to buildings where sound levels range from 45 to 48 dB(A) and from 48 to 51 dB(A), which are indicated in green tones on the acoustic maps.
Canadian Acoustical Association / Association canadienne d'acoustique
2013-03-01 00:00:00
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/2600
Canadian Acoustics; Vol. 41 No. 1 (2013)
eng
Copyright (c)
oai:jcaa.caa-aca.ca:article/2625
2014-01-31T02:22:20Z
jcaa:ART-NC
"140130 2014 eng "
2291-1391
0711-6659
dc
THEORETICAL ANALYSIS OF LINED -DUCT SOUND ATTENUATION
Bibby, Chris
Acoustics and Noise Research Group, University of British Columbia
Hodgson, Murray
This paper investigates theoretically how duct geometry and liner thickness affect the attenuation of fundamental-mode
sound propagation in a lined duct. The study was done to satisfy the need for a greater understanding of interior natural-
ventilation openings and of silencers implemented to improve the acoustical performance (‘ventilators’), and to provide
engineers and architects with optimal-design guidelines. It assumed ventilators of the simplest form – straight, acoustically-
lined ducts of rectangular cross-section. An analytical solution is presented for the attenuation of the fundamental mode in
such a duct. Duct-liner thickness does not affect high-frequency performance; however, it limits low-frequency performance.
A 25-mm liner is likely not thick enough to be effective, but a 100-mm liner may be excessive. Increasing the duct height
reduces the attenuation at all frequencies; in order to provide effective attenuation through the 4000-Hz band, the height
should not exceed 100 mm. If the cross-sectional aspect ratio of a duct is greater than 10, or the duct is only lined on two
opposing surfaces, the attenuation of its fundamental mode is in effect identical to that of a 2D lined duct. Provided that the
duct liner and height are such that the silencer is effective at absorbing sound at a given frequency, reducing the aspect ratio
towards unity will result in large attenuation gains.
Canadian Acoustical Association / Association canadienne d'acoustique
2014-01-30 00:00:00
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/2625
Canadian Acoustics; Vol. 41 No. 3 (2013)
eng
Copyright (c)
oai:jcaa.caa-aca.ca:article/2628
2014-03-09T01:54:27Z
jcaa:ART-NC
"140301 2014 eng "
2291-1391
0711-6659
dc
Noise Output of Road Racing Motorcycles From Measured Leq Data
Mitchell, Andrew K.
School of Engineering, Acadia University, Wolfville, Nova Scotia
This paper reports the results of an experimental study of the noise output from road racing motorcycles competing in the Canadian Superbike race series. Leq data from single-point measurements are presented for five events, which are then analyzed to determine an energy-average noise output per competitor at each event. The analysis, which considers track geometry and total time spent on track by all competitors, seems to indicate a moderately rising trend in the noise output per participant over time that is attributed to the changing composition of the field. The single-number noise descriptor obtained is suggested as a useful tool for predicting noise levels at future events at this or other venues.
Canadian Acoustical Association / Association canadienne d'acoustique
2014-03-01 00:00:00
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/2628
Canadian Acoustics; Vol. 42 No. 1 (2014)
eng
Copyright (c)
oai:jcaa.caa-aca.ca:article/2651
2015-04-01T23:01:10Z
jcaa:ART-NC
"150401 2015 eng "
2291-1391
0711-6659
dc
Urban Noise Assessment Based on Noise Mapping and Measurements
Filho, Jucelino José de Souza
Federal University of Mato Grosso do Sul – UFMS, Brazil
Steffen, Jorge Luiz
Federal University of Mato Grosso do Sul – UFMS, Brazil
Andreasi, Wagner Augusto
Laboratory of Analysis and Development of Buildings, Federal University of Mato Grosso do Sul – UFMS, Brazil
Zannin, Paulo Henrique Trombetta
Laboratory of Environmental and Industrial Acoustics and Acoustic Comfort, Federal University of Paraná – UFPR, Brazil
Noise pollution was evaluated in a large city in Latin America based on in situ measurements taken at 174 points and on noise maps. The noise maps were calculated using Predictor 7810 version 8.11 software. Three distinct areas in the city of Campo Grande (Brazil) were evaluated: 1) Commercial sector, 2) Mixed sector (commercial and residential), and 3) Residential sector. The noise maps indicate the presence of noise pollution in the Commercial and Mixed sectors, as well as the fact that parts of the Residential sector are noise polluted but that it still has large areas where the noise limit of 55 dB(A) is respected.
Canadian Acoustical Association / Association canadienne d'acoustique
2015-03-01 00:00:00
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/2651
Canadian Acoustics; Vol. 43 No. 1 (2015)
eng
Copyright (c) 2015
oai:jcaa.caa-aca.ca:article/2658
2015-12-21T19:26:33Z
jcaa:ART-NC
"151215 2015 eng "
2291-1391
0711-6659
dc
Study of Cavity Modal Damping: A Numerical Methodology for Acoustic Evaluation Using the Finite Element Method in Vehicle Bodies Based on Experimental Tests
Ferreira, Tiago Simão
Pontifical University Catholic (PUC MINAS), Department of Mechanical Engineering, Av. Dom José Gaspar, 500, Belo Horizonte, Brazil. http://www.cng.ifmg.edu.br/
Magalhães, Pedro Américo
Pontifical University Catholic (PUC MINAS), Department of Mechanical Engineering, Av. Dom José Gaspar, 500, Belo Horizonte, Brazil. http://pucminas.br/destaques/destaques.php
Moura, Frederico Luiz
Federal University of Minas Gerais (UFMG), Department of Mechanical Engineering, Av. Antônio Carlos, 6627 – Pampulha, Belo Horizonte, Brazil https://www.ufmg.br/
Ferreira, Timoteo Simão
Federal University of Minas Gerais (UFMG), Department of Mechanical Engineering, Av. Antônio Carlos, 6627 – Pampulha, Belo Horizonte, Brazi https://www.ufmg.br/
This work focuses on finding a numerical solution for vehicle acoustic studies and improving the usefulness of the “Numerical experimental” parameters for the development stage of a new automotive project. Specifically, this research addresses the importance of cavity modal damping for vehicle exerts during numerical studies. This research then seeks to suggest standardized parameter values of modal cavity damping in vehicular acoustic studies.
This standardized value of modal damping cavity is of great importance for the study of vehicular acoustics in the automotive industry because it would allow the industry to begin studies of the acoustic performance of a new vehicle early in the conception phase with a reliable estimation that would be close to the final value measured in the design phase. It is common for the automotive industry to achieve good levels of numerical-experimental correlation in acoustic studies after the prototyping phase because this phase can be studied with feedback from the simulation and experimental modal parameters.
Thus, this research suggests values for cavity modal damping, which are divided into two parts due to their behavior:
?(x) =-0.0126(x-100)+6.15 as a variable function to analyze up to 100 Hz and 6.15% of cavity modal damping constant for studies between 30 Hz and 100 Hz.
The sequence of this study shows how we arrived at these values.
Canadian Acoustical Association / Association canadienne d'acoustique
2015-12-15 00:00:00
application/pdf
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/2658
Canadian Acoustics; Vol. 43 No. 4 (2015)
eng
Copyright (c) 2015 Tiago Simão Ferreira, Pedro Américo Magalhães, Frederico Luiz Moura, Timoteo Simão Ferreira
oai:jcaa.caa-aca.ca:article/2866
2016-12-06T01:51:38Z
jcaa:ART-NC
"161203 2016 eng "
2291-1391
0711-6659
dc
A Comparative Study Between Different Helmholtz Resonator Systems
Mahmud, Md. Amin
"Islamic University of Technology (IUT)"
Islam, Md. Shahriar
"Islamic University of Technology (IUT)''
Hossain, Md. Zahid
"Islamic University of Technology (IUT)''
Morshed, Mir Md. Maruf
Jubail University College
This paper proposes a best fit cylindrical Helmholtz resonator system attached to a duct for attenuating low frequency noise within 300 Hz using finite element method. Initially, an optimized system of two identical 2-DOF resonators in terms of relative position and orientation by adapting a published single 2-DOF resonator system. The optimum relative position of the two resonators is studied by placing them at less than antinode, antinode and node of the wavelength of sound source and the optimum relative orientation between the resonators is also found out at that optimum relative spacing. Finally, the optimized system of two identical 2-DOF resonators is compared with three published studies of single 2-DOF, single 1-DOF and two identical 1-DOF resonator systems and the results indicates that two identical 2-DOF resonator system provide a comparatively wider bandwidth of noise attenuation within 300 Hz. The obtained analytical and numerical results of transmission loss for the adapted single 2-DOF have been validated with that of the published experimental result and a good agreement is found.
Canadian Acoustical Association / Association canadienne d'acoustique
2016-12-03 00:00:00
application/pdf
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/2866
Canadian Acoustics; Vol. 44 No. 4 (2016)
eng
Copyright (c) 2016 Md. Amin Mahmud, Md. Shahriar Islam, Md. Zahid Hossain, Mir Md. Maruf Morshed
oai:jcaa.caa-aca.ca:article/3034
2017-06-30T15:48:06Z
jcaa:ART-NC
"170630 2017 eng "
2291-1391
0711-6659
dc
Shape Optimization of Reactive Mufflers Using Threshold Acceptance and FEM Methods
Khamchane, Abdelkader
Laboratoire de Mécanique, Matériaux et Energétique (L2ME)
Université de Bejaia, Faculté de Technologie
Targa ouzemour
Bejaia, DZ 06000, Algeria
Khelfaoui, Youcef
Laboratoire de Mécanique, Matériaux et Energétique (L2ME)
Université de Bejaia, Faculté de Technologie
Targa ouzemour
Bejaia, DZ 06000, Algeria
Hamtache, Brahim
Laboratoire de Mécanique, Matériaux et Energétique (L2ME)
Université de Bejaia, Faculté de Technologie
Targa ouzemour
Bejaia, DZ 06000, Algeria
The Shape optimization of reactive muffler under space constraint has become of great importance in the design of quieter environments. In this paper the acoustic performance of three different expansion-chamber mufflers with extended tube under space constraint is presented. A shape optimization analysis is performed using a scheme called Threshold Acceptance (TA), the best design obtained by the shape optimization method are analyzed by Finite Element Method (FEM). This numerical approach is based on the maximization of the sound transmission loss (STL) using the Transfer Matrix Method (TMM), a modelling method based on the plane wave propagation model. The FEM solution is based on the Acoustic Power method, a standard computational code COMSOL Multiphysics is used to analyze in 3D the sound attenuation of the mufflers by the FE method. The acoustical ability of the mufflers obtained is than assessed by comparing the FEM solution with the analytical method. Results show that the maximal STL is precisely located at the desired targeted tone. In addition, the acoustical performance of muffler with outlet extended tube is found to be superiors to the other one. Consequently, this approach provides a quick scheme for the shape optimization of reactive mufflers.
Canadian Acoustical Association / Association canadienne d'acoustique
2017-06-30 08:48:06
application/pdf
application/pdf
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3034
Canadian Acoustics; Vol. 45 No. 2 (2017)
eng
Copyright (c) 2017 Abdelkader KHAMCHANE, Youcef KHELFAOUI, Brahim HAMTACHE
oai:jcaa.caa-aca.ca:article/3059
2018-03-13T19:14:56Z
jcaa:ART-NC
"180313 2018 eng "
2291-1391
0711-6659
dc
Impact of Traffic-Related Environmental Noise on School Children and Teachers in a Northeast Brazilian Capital
Ary Junior, Ivan José
Universidade Federal do Ceara http://www.det.ufc.br
Azevedo Filho, Mario Angelo Nunes de
Universidade Federal do Ceara http://www.det.ufc.br http://orcid.org/0000-0003-0365-642X
Mota, Francisco Suetônio Bastos
Universidade Federal do Ceara http://www.deha.ufc.br
Peixoto, Nara Gabriela de Mesquita
Instituto Federal de Educação, Ciência e Tecnologia do Ceará http://www.ifce.edu.br
Brito, Francisco Aurélio Chaves
Prefeitura Municipal de Fortaleza http://www.fortaleza.ce.gov.br
Environmental noise in urban areas is known to cause functional abnormalities reflected in human health and behavior. In developing countries such as Brazil, public schools are exposed to high levels of noise due in part to poor infrastructure, especially with regard to noise protection. In schools exposed to noise levels above the limits specified by regulations and international guidelines, students and teachers are at greater risk of health problems, and performance may be compromised. In this study we evaluated the impact of environmental noise on children and teachers at three public schools (a kindergarten, an elementary school and a high school) in a Northeast Brazilian metropolis, with emphasis on noise generated by street, metro and air traffic. Environmental noise maps were generated with software and teachers were administered questionnaires focusing on the impact of noise pollution on health and performance. The study was intended to subsidize efforts at urban planning and public policy making by measuring actual noise levels and probing their possible effects. As shown by our results, public schools are in urgent need of noise protection measures, and enforcement of noise emission regulations for public transportation needs to be more emphatic.
Canadian Acoustical Association / Association canadienne d'acoustique
2018-03-13 12:14:26
application/pdf
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3059
Canadian Acoustics; Vol. 46 No. 1 (2018)
eng
Copyright (c) 2018 Ivan José Ary Junior, Mario Angelo Nunes de Azevedo Filho, Francisco Suetônio Bastos Mota, Nara Gabriela de Mesquita Peixoto, Francisco Aurélio Chaves Brito
oai:jcaa.caa-aca.ca:article/3185
2018-10-16T15:08:35Z
jcaa:ART-NC
"180622 2018 eng "
2291-1391
0711-6659
dc
Experimental Evaluation Of Acoustic Characteristics Of Ball Straw Walls
Trabelsi, Abderraouf
Académie Militaire, département génie civil, fondouk jadid
Kammoun, Zied
Université de Carthage, Institut Supérieur des Technologies de l’Environnement de l’Urbanisme et du Bâtiment
Natural fibres are becoming a valid alternative for sound absorption treatments at a reduced cost. Indeed, these fibres generally present good insulation properties and presents no health hazard.
To insulate industrial, road traffic and railroad noises, straw ball can be envisaged as insulation materials. Thus, This paper presents an investigation in the characterizations of acoustic walls developed from straw ball. In order to protect straw fibres and improve the mechanical behaviour, a second variant of straw wall is made with ball straw immersed in the cement slurry.
The experimental tests, have been conducted in an open space to predict acoustic performances and measure absorption coefficient, Noise Reduction Coefficient (NRC) and transmission factor. The acoustic properties are determined by experiments at frequency intervals between 125 Hz and 4000 Hz. Simulation shows a very good acoustic performances for the straw ball wall, with the absorption of more than 70 % of the incident noise for medium and high frequencies and the transmission of no more then 21% of the incident noise for all studied cases.
Canadian Acoustical Association / Association canadienne d'acoustique
2018-06-22 00:00:00
application/pdf
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3185
Canadian Acoustics; Vol. 46 No. 2 (2018)
eng
Copyright (c) 2018 Abderraouf Trabelsi, Zied Kammoun
oai:jcaa.caa-aca.ca:article/3308
2020-02-28T00:27:44Z
jcaa:ART-NC
"191106 2019 eng "
2291-1391
0711-6659
dc
Sound Attenuation of an Acoustic Barrier Made with Metamaterials
Iannace, Gino
Universita degli Study della Campania "Luigi Vanvitelli"
Berardi, Umberto
Ryerson University https://sites.google.com/site/umbertoberardihomepage/ http://orcid.org/0000-0002-0508-6195
Ciaburro, Giuseppe
Università degli Studi della Campania « Luigi Vanvitelli »
Trematerra, Amelia
Università degli Studi della Campania « Luigi Vanvitelli »
Metamaterials represent a new approach in applied acoustics and noise control fields, although the first studies of them date back to a half century ago to Viselago, and later to Pendry. In this paper, after a brief introduction to the state of art of metamaterials for acoustic applications, the sound attenuation of an acoustic barrier made following metamaterial rules is investigated. A 1:10 scale model was built using cylindrical wooden bars, 30 cm high and 1.5 cm in diameter. The total length of the barrier model was 100 cm. The barrier was investigated for four alternating rows of cylindrical bars, spacing each bar with an empty space to create different regular geometries. The insertion losses of each configuration are reported.
Canadian Acoustical Association / Association canadienne d'acoustique
2020-02-25 01:46:48
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3308
Canadian Acoustics; Vol. 47 No. 4 (2019)
eng
Copyright (c) 2019 Umberto Berardi
oai:jcaa.caa-aca.ca:article/3370
2020-06-28T00:54:50Z
jcaa:ART-NC
"200615 2020 eng "
2291-1391
0711-6659
dc
Numerical and Experimental Study of Various Interior Source Identification Methods With Circular Microphone Array
Khatami, Iman
chabahar maritime university
Berry, Alain
Universite de sherbrooke
This study addresses an assessment of some sound identification methods using circular microphone arrays for sources interior to the array circle. Various techniques are compared, including classical beamforming (CB), regularized inverse methods (Tikhonov regularization), L1- generalized inverse beamforming (L1-GIB), deconvolution methods CLEAN-PSF, CLEAN-SC, as well as more recent inverse methods using beamforming regularization (BFR). To highlight the advantages and disadvantages of these methods, several numerical and experimental application examples are discussed. When multiple sources are searched, the results show that the method of choice depends on the correlation, directivity and relative level of the sources.
Canadian Acoustical Association / Association canadienne d'acoustique
2020-06-27 17:54:50
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3370
Canadian Acoustics; Vol. 48 No. 2 (2020)
eng
Copyright (c) 2020 iman khatami, Alain Berry
oai:jcaa.caa-aca.ca:article/3372
2020-06-28T00:54:50Z
jcaa:ART-NC
"200511 2020 eng "
2291-1391
0711-6659
dc
First Steps Towards a Methodology to Assess the Influence of Noise on a Natural Area
Hernández-Molina, Ricardo
Fernádez-Zacarías, Francisco
David Bienvenido-Huertas
University of Seville
Cueto-Ancela, José Luis
Natural sounds are integral elements of the natural environment that are frequently associated with natural parks and similar areas. They are, indisputably, inherent components of landscapes and their contents of natural and historical features, and particularly of their wildlife. Natural sounds constitute an indicator of the health of the wildlife habitat and the diverse ecosystems that comprise such areas. The present generation has an acknowledged obligation to conserve these natural resources for the benefit of those to come.
In the process of planning to achieve the objectives of acoustic quality of the natural soundscape, the fundamental principle for determining the health of the natural environment, which forms part of the general planning of the natural parks, is the preservation of the soundscape at levels compatible with the characteristics of the park. When deficiencies are identified, action needs to be taken to restore the soundscape to its natural condition. The objective of this project is to analyse the existence of “non-natural” noises foreign to the natural environment and protect the Natural Soundscape from intrusive acoustic impacts. The study was carried out on the "natural area" of Anceu, located in the municipality of Pontecaldelas in the province of Pontevedra, Galicia (Spain).
Canadian Acoustical Association / Association canadienne d'acoustique
2020-06-27 17:54:50
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3372
Canadian Acoustics; Vol. 48 No. 2 (2020)
eng
Copyright (c) 2020 Ricardo Hernández-Molina, Francisco Fernádez-Zacarías, David Bienvenido-Huertas, José Luis Cueto-Ancela
oai:jcaa.caa-aca.ca:article/3380
2020-12-28T01:20:28Z
jcaa:ART-NC
"201213 2020 eng "
2291-1391
0711-6659
dc
Variation in the Acoustic Measurement of Earbud Earphones in an Anechoic Chamber Due to Changes in the Earphone Placement in Ear Concha
Pawar, S J
Motilal Nehru National Institute of Technology Allahabad, Prayagraj (UP) INDIA http://orcid.org/0000-0003-0309-7939 https://orcid.org/0000-0003-0309-7939
Liu, Y. C.
Feng Chia University, Taichung 40724, Taiwan, Republic of China (ROC) https://orcid.org/0000-0003-4797-3179
Huang, Jin H.
Feng Chia University https://orcid.org/0000-0003-4192-9935
The growth of 4C products encouraged by innovations has stimulated the persistent development of earphones for high-quality sound reproduction. A typical earbud earphone (EE) is located in the concha of the human ear facing an ear-canal. The placement of earphones in the concha plays a remarkable role in the sound pressure level (SPL) response of an earphone. In this study, ten earphones (E1-E10) were tested for the SPL and total harmonic distortion (THD) response using head and torso simulator (HATS) in an anechoic chamber. The SPL and THD responses of all earphones at position-1 and orientation-1 were declared as a benchmark and a characteristic earphone signature. Hence, based on the responses of all earphones at all orientations and positions, it is concluded that there is a variation in the SPL and THD responses due to change in position and orientation of earphone in the concha. Based on the proposition presented in the work and the safe daily sound exposure, it has been resolved that the variation in the SPL affects the perceived loudness of music/sound and can cause significant differences in the daily sound exposure limit for a human being.
Canadian Acoustical Association / Association canadienne d'acoustique
2020-12-13 00:00:00
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3380
Canadian Acoustics; Vol. 48 No. 4 (2020)
eng
Copyright (c) 2020 S. J. Pawar, Y. C. Liu, Jin H. Huang
oai:ojs.pkp.sfu.ca:article/3380
2020-12-14T00:38:06Z
jcaa:ART-NC
oai:jcaa.caa-aca.ca:article/3384
2021-07-07T20:35:19Z
jcaa:ART-NC
"210707 2021 eng "
2291-1391
0711-6659
dc
Shape Optimization Of Extended Tube Muffler Using Threshold Acceptance, Simulated Annealing And FEM Methods
abdelkader, khamchane
university of Bejaia https://orcid.org/0000-0003-0167-2231
Khelfaoui, Youcef
Laboratoire de Mcanique, Matériaux et Energétique
Hamtache, Brahim
Laboratoire de Mécanique, Matériaux et Energétique
Exhaust noise must meet customer expectations, legislation targets, and cost reduction which call for design optimization of the exhaust systems in the design phase. Shape optimization of reactive mufflers using algorithms became as one of important solutions to improve the acoustic performance of compact mufflers used in a limited space.
In this paper, a numerical assessment of single expansion-chamber muffler with extended tube under limited space is performed by the maximization of the sound transmission loss (STL) using the Transfer Matrix Method (TMM) and Finite Element Method (FEM). This shape optimization analysis is performed using novel schemes called Threshold Acceptance (TA) and Simulated Annealing (SA), a robust schemes used to search for the global optimum by imitating the metal’s heating process, an accuracy check on the mathematical model is performed. Also, for reliability check on the TA and SA methods, the STL’s maximization with respect to a one-tone noise is introduced, the best designs obtained by the two methods are compared and analyzed by Finite Element Method (FEM). The Transfer Matrix Method (TMM) is a modelling method based on the plane wave propagation model and the FEM solution used to analyze the STL of the shape optimized mufflers is based on the Acoustic Power method. A standard computational code COMSOL Multiphysics is used to analyze in 3D the sound attenuation of the muffler by the FEM method. The acoustical ability of the muffler obtained is than assessed by comparing the FEM solution with the analytical method. Results show that the best acoustical performance is obtained with TA optimizer and the maximal STL is precisely located at the desired targeted tone. Consequently, the optimal approach on the design of single expansion-chamber muffler with extended tube presented in this study provides quick and novel schemes for the shape optimization of muffler under limited space.
Canadian Acoustical Association / Association canadienne d'acoustique
2021-07-07 00:00:00
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3384
Canadian Acoustics; Vol. 49 No. 2 (2021)
eng
Copyright (c) 2021 khamchane abdelkader, Youcef Khelfaoui, Brahim Hamtache
oai:jcaa.caa-aca.ca:article/3416
2021-07-07T20:35:19Z
jcaa:ART-NC
"210707 2021 eng "
2291-1391
0711-6659
dc
Influence Of Different Distribution Patterns Of Holes On Single Micro-Perforated Panel Sound Absorption Behaviour
Teleb, Hatem
Assistant Researcher https://orcid.org/0000-0003-3795-007X
Abd-Elbasseer, Mohamed
Acoustics Laboratory, National Institute of Standards (NIS), Giza, Egypt
Mahmoud, Abd Elfattah A
Acoustics Laboratory, National Institute of Standards (NIS), Giza, Egypt
Mohamed, Hatem Kh.
Acoustics Laboratory, National Institute of Standards (NIS), Giza, Egypt
Micro-perforated panels have become a valid broadband sound absorber option lately. Their applicability is wide since they are promising for absorbing sound energy for several applications, such as automotive, HVAC systems, noise barriers, etc. This study investigates the effect of different distribution patterns of holes, perforation ratio, air gap depth, and the hole geometry on single micro-perforated panels' sound absorption behavior. Four different distribution patterns (Circle, Square, Triangle, and Random) of orifices are designed and fabricated on a surface of metal sheet of thickness 1 mm with hole diameter 1mm, and air gap depth between the panel and the back wall 100 mm. Each distribution pattern of the four different patterns was perforated with seven perforation ratios (0.12%, 0.36%, 0.48%, 0.60%, 0.84%, 1.1%, and 1.9%).The measurements were carried out using the two-microphone impedance tube in the low-frequency range from 100 Hz to 1000 Hz. Although the results revealed no significant difference between the absorption coefficients of different holes' patterns at all the perforation ratios, the random pattern is slightly higher than other distribution patterns. Increasing the air gap depth improved the average sound absorption coefficient in the frequency range from 160 Hz to 630 Hz from 0.29 to 0.51. Moreover, Changing the hole geometry from circle to square and triangle enhanced the sound absorption coefficient of about 11 % and 12 %. Good consistency between the theoretical calculations and the experimental results is obtained.
Canadian Acoustical Association / Association canadienne d'acoustique
2021-07-07 00:00:00
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3416
Canadian Acoustics; Vol. 49 No. 2 (2021)
eng
Copyright (c) 2021 Hatem Teleb, Mohamed Abd-Elbasseer, Abd Elfattah A Mahmoud, Hatem Kh. Mohamed
oai:jcaa.caa-aca.ca:article/3430
2022-07-25T20:47:14Z
jcaa:ART-NC
"220725 2022 eng "
2291-1391
0711-6659
dc
Determination of Acoustic Characteristics of Melamine Foam with Experimental Validation
Zai, Dr. Behzad Ahmed
SUPARCO
Sami, Saad
Space and upper atmosphere research commission
Shahzad, Majid
dr_majid@engineer.com
Ali, Rashid
Ghulam Ishaq Khan Institute of Engineering
Space launch vehicles experience severe dynamic loadings throughout the flight. Acoustic loads are one such load which are very critical to the launch vehicle at the time of ignition and take off. The amplitudes of acoustic loadings are generally very high and required to be diminished to save electronic components. Typically, one of the most common and efficient insulating material is Melamine Foam (MF). In this paper, the acoustic and environmental noise reduction MF panels of variable thicknesses (25, 50 and 75mm) are analyzed. Commercial FEA software is used to estimate the acoustic parameters which are experimentally validated using impedance tube based on transfer matrix method. The impedance tube can measure the normal incident sound absorption coefficient and transmission loss for frequency range of 64 Hz to 6.2 kHz. A conventional, two-microphone impedance tube, is connected to a sample holder downstream of the first microphone pair and a section downstream of the sample holder that accommodates a second pair of microphones. Two separate arrangements of impedance tube are used to measure the absorption coefficient and transmission loss. The FEA and experimental results are compared and found in good agreements Furthermore, the optimized insulation foam thickness is obtained based on required acoustic parameters.
Canadian Acoustical Association / Association canadienne d'acoustique
2021-12-27 00:00:00
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3430
Canadian Acoustics; Vol. 49 No. 4 (2021)
eng
Copyright (c) 2021 Dr. Behzad Ahmed Zai, Saad Sami, Majid Shahzad, Rashid Ali
oai:jcaa.caa-aca.ca:article/3435
2022-07-25T20:46:47Z
jcaa:ART-NC
"220725 2022 eng "
2291-1391
0711-6659
dc
Subjective Analysis Of Soundscape In Three Areas In The Brazilian City In The Legal Amazon Region
Ferreira, Lucas Rafael
Federal University of Santa Maria https://orcid.org/0000-0002-2574-7990
Borges, Erika Fernanda Toledo
Universidad do Estado de Mato Grosso
Grigoletti, Giane de Campos
Sinop city has about 143,000 inhabitants and is located in the north of Mato Grosso in the Legal Amazon region. The city has large green areas and some of them are suffering alterations in the soundscape through urbanization, such as the Aquarela do Brasil neighborhood, Parque Florestal, and Tarumãs Avenue. The soundscapes in these three locations were defined as objects of study because they have different typologies and uses, two of them wooded and another with little vegetation located in the center of the city. The objective of the research is to identify the preservation points of the soundscape and to define which of them interfere in the feeling of comfort of people from a subjective analysis. Questionnaires were answered by users to understand the soundscapes and the relation of comfort within the environment they have with the identification of different sounds of the soundscape. The subjective results involve physical, sensitive, and psychological variables, which are presented and claimed in this article. It was verified that the existing sound levels in the analyzed locations are above the limit imposed by the Brazilian regulation, however, there is a satisfaction of comfort defined by most users of these urban spaces.
Canadian Acoustical Association / Association canadienne d'acoustique
2021-12-27 00:00:00
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3435
Canadian Acoustics; Vol. 49 No. 4 (2021)
eng
Copyright (c) 2021 Lucas Rafael Ferreira, Erika Fernanda Toledo Borges, Giane de Campos Grigoletti
oai:jcaa.caa-aca.ca:article/3455
2022-07-25T20:28:36Z
jcaa:ART-NC
"220725 2022 eng "
2291-1391
0711-6659
dc
Using a Passive Feedback Connection to Control Low-Frequency Pressure Fluctuations in a Wind Tunnel
Waudby-Smith, Peter
Aiolos Engineering Corporation
Joshi, Antrix
Aiolos Engineering Corporation https://orcid.org/0000-0001-7304-1266
Sooriyakumaran, Christopher
Aiolos Engineering Corporation
Gabriel, Christoph
Grabenstein, Martin
A Passive Feedback Connection (PFC) was evaluated for use in an aero-acoustic wind tunnel. The PFC can reduce the high-amplitude low-frequency pressure fluctuations in the wind tunnel circuit. In addition, the PFC can also reduce non-periodic fluctuations in wind speeds, i.e., not just fluctuations associated with resonances arising from the coupling of open jet pressure instabilities with circuit modes. The PFC achieved these results without significantly altering the axial static pressure gradient in the wind tunnel.
Canadian Acoustical Association / Association canadienne d'acoustique
2022-07-25 13:28:32
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3455
Canadian Acoustics; Vol. 50 No. 1 (2022)
eng
Copyright (c) 2022 Peter Waudby-Smith, Antrix Joshi, Christopher Sooriyakumaran, Christoph Gabriel, Martin Grabenstein
oai:jcaa.caa-aca.ca:article/3469
2023-03-12T09:30:53Z
jcaa:ART-NC
"230312 2023 eng "
2291-1391
0711-6659
dc
Hybrid Method for the Design and Optimization of a Silent Exhaust System for Formula Racing Cars
Mohamad, Barhm
Faculty of Mechanical Engineeing and Informatics, University of Miskolc-3515 Miskolc, Hungary https://orcid.org/0000-0001-8107-6127
Zelentsov, Andrei
Dans ce travail, une analyse CFD à plusieurs niveaux a été appliquée pour la conception d’un Système d’échappement silencieux de voiture de course Formula présentant de meilleures caractéristiques de niveau de pression acoustique (SPL) et de réponse dynamique des fluides. Les approches développées et appliquées pour le processus d'optimisation vont de la simulation 1D à la simulation CFD entièrement 3D, en explorant des approches hybrides basées sur l'intégration d'un modèle 1D avec des outils 3D. Les silencieux modernes ont généralement un système complexe de chambres et de voies d’écoulement. Il existe toute une gamme de mécanismes d’amortissement et d’absorption du son qui atténuent le son transmis par le silencieux et les tuyaux. Deux méthodes de calcul ont été sélectionnées pour cette étude. Le silencieux a une structure interne complexe contenant un tuyau perforé et un matériau fibreux. Le fichier CAO du silencieux a été créé pour développer le modèle FEA dans (AVL BOOST v2017) et un autre logiciel de conception avancée commercial (SolidWorks 2017). Le modèle FEA a été conçu pour surveiller les propriétés d'écoulement, la pression et la vitesse. Une fois le modèle vérifié, des études de sensibilité des paramètres de conception ont été effectuées pour optimiser le niveau de pression acoustique du silencieux. Les résultats de l'analyse par logiciels sont inclus dans l'article. Des recommandations sont formulées pour obtenir des courbes de niveau de pression acoustique (SPL) plus lisses pour diverses méthodes de mesure.
Canadian Acoustical Association / Association canadienne d'acoustique
2023-03-12 01:30:53
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3469
Canadian Acoustics; Vol. 50 No. 4 (2022)
fre
Copyright (c) 2022 Barhm Mohamad; Andrei Zelentsov
oai:jcaa.caa-aca.ca:article/3477
2022-12-11T11:21:02Z
jcaa:ART-NC
"221211 2022 eng "
2291-1391
0711-6659
dc
Comparison of the Sound Transmission Variability with Published Results on Coupling Loss
Magalhaes, Max
Federal University of Minas Gerais
Department of Structural Engineering
Whilst most predictions in building acoustics and design invariably use published and readily available models, some attempt to quantify confidence limits that cover most cases would be invaluable. For instance, the parameters (e.g. room dimensions, panel position, room absorption, etc.) are shown to have a substantial effect on Noise Reduction (NR) and Coupling Loss Factor (CLF), the latter being a very important factor for predicting sound transmission using Statistical Energy Analysis (SEA). A Statistical Energy Analysis (SEA) model was implemented and used herein for the prediction of CLFs between two rooms. Thus, the main goal this research is to make an initial parametric investigation for the Coupling Loss Factors (CLFs) and then compare their variability with theoretical upper and lower bound curves previously presented in the literature for structure coupling. The usefulness of SEA as a framework of analysis can be assessed by the estimation of variance and confidence intervals. In addition, the spatial-average mean square sound pressure for each SEA subsystem was estimated via a Component Mode Synthesis (CMS) model developed in a previous paper. In summary, the room acoustic pressures were obtained via a CMS procedure and subsequently used in a SEA model where the equivalent CLFs were evaluated on basis of SEA assumptions. The influence of other SEA parameters, such as modal density and modal overlap was also considered.
Canadian Acoustical Association / Association canadienne d'acoustique
2022-12-11 03:20:54
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3477
Canadian Acoustics; Vol. 50 No. 2 (2022)
eng
Copyright (c) 2022 Max Magalhaes
oai:jcaa.caa-aca.ca:article/3527
2022-12-11T11:20:59Z
jcaa:ART-NC
"221211 2022 eng "
2291-1391
0711-6659
dc
Vibration Transmission Across Junctions of Walls and Floors in an Apartment Building – A Case Study
Magalhaes, Max
Federal University of Minas Gerais
Department of Structural Engineering
Libero, Hugo
Universidade Federal de Goiás https://orcid.org/0000-0001-6618-3282
The perception of sound radiated from a building floor is greatly influenced by the rooms in which it is immersed and by the position of both listener and source. The main question that remains unanswered is related to the influence of the source position on the sound power radiated by a complex wall-floor system in buildings. This research is concerned with the investigation of vibration transmission across walls and floors in buildings. It is primarily based on the determination of vibration reduction index via experimental tests. Knowledge of this parameter may help in predicting noise and vibration propagation in building components. First, the physical mechanisms involving vibration transmission across structural junctions is described. An experimental set-up is performed to aid this investigation. The experimental tests have showed that the vibration generation in the walls and floors are directed related to their size and boundary conditions. It is also shown that the vibration source position can affect the overall vibration spectrum significantly. Second, the characteristics of the noise spectra inside the rooms due to a impact source (tapping machine) are also presented. Conclusions are drawn for the general trend of vibration and noise spectrum of the structural components and rooms respectively. In summary, the aim of this paper is to investigate the vibro-acoustical behavior of building floors and walls under floor impact excitation. The impact excitation was at distinct positions on the slab. The analysis has highlighted the main physical characteristics of the vibration transmission mechanism.
Canadian Acoustical Association / Association canadienne d'acoustique
2022-12-11 03:20:54
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3527
Canadian Acoustics; Vol. 50 No. 2 (2022)
eng
Copyright (c) 2022 Max Magalhaes, Mr
oai:jcaa.caa-aca.ca:article/3935
2023-09-12T03:21:19Z
jcaa:ART-NC
"230824 2023 eng "
2291-1391
0711-6659
dc
Finite Element Analysis of Honeycomb Membrane-Type Acoustic Metamaterial
Laly, Zacharie
Université de Sherbrooke https://orcid.org/0000-0003-4757-3984 https://orcid.org/0000-0003-4757-3984
Mechefske, Christopher
Queen's University https://orcid.org/0000-0002-3509-0339
Ghinet, Sebastian
National Research Council Canada https://orcid.org/0000-0001-5501-4950
Ashrafi, Behnam
National Research Council Canada
Kone, Charly T.
National Research Council Canada
In this paper, a honeycomb membrane-type acoustic metamaterial made of a honeycomb structure with embedded membrane layers is investigated using the finite element method. This lightweight material presents excellent transmission loss (TL) at low frequency. The impacts of the membrane material properties and of the honeycomb cell size on the transmission loss are studied numerically. It is shown that the TL increases over a large frequency band when the honeycomb cell size decreases while the displacement magnitude of the membrane is reduced and the mode shape is affected. The influence of the membrane thickness on the TL and displacement magnitude and mode shape at different frequencies is presented. It is observed that the TL presents multiple resonant peaks as the thickness of the membranes is reduced. An improvement of the TL is observed around the anti-resonant frequencies by increasing the damping loss factor of the membrane, which causes a reduction of the resonant displacement magnitude and TL peaks amplitude. Honeycomb structures with two and three embedded membrane layers are analyzed numerically and the effects of the number of membrane layers and of the thickness of the air gap between membranes are illustrated. The investigated metamaterial can be useful in many noise control engineering applications.
Canadian Acoustical Association / Association canadienne d'acoustique
2023-08-24 00:00:00
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3935
Canadian Acoustics; Vol. 51 No. 2 (2023)
eng
Copyright (c) 2023 Zacharie Laly, Christopher Mechefske, Sebastian Ghinet, Behnam Ashrafi, Charly T. Kone
oai:jcaa.caa-aca.ca:article/3944
2023-09-12T03:21:19Z
jcaa:ART-NC
"230824 2023 eng "
2291-1391
0711-6659
dc
Assessment Of Noise In The Campus Of École De Technologie Supérieure In Montréal And Proposal Of An Acoustic Metamaterial For The Reduction Of Electrical Transformer Noise
Doutres, Olivier
École de technologie supérieure (ÉTS) https://orcid.org/0000-0003-3103-488X
Lopez, Maël
ÉTS
Rouard, Kévin
ÉTS https://orcid.org/0009-0009-7927-5931
Campagna, Louis-Philippe
ÉTS
Cougoulic, Titouan
ÉTS https://orcid.org/0009-0002-4081-0617
Jutras, Anthony
ÉTS https://orcid.org/0009-0001-8511-5311
Lauzon, David
ÉTS
Pépin-Pagé, Pierre-Luc
ÉTS https://orcid.org/0009-0001-1957-5387
Purson, Alexis
ÉTS https://orcid.org/0009-0002-2412-641X
Les campus universitaires situés au cœur des villes peuvent être exposés à des niveaux de bruit importants qui peuvent nuire à l’apprentissage des étudiants et étudiantes, à la performance de la communauté enseignante et des membres du personnel mais aussi à la qualité de vie des résidents et résidentes du quartier. Cet article présente les résultats d’un projet d’étude réalisé par des étudiants du cours d’acoustique industrielle de l’École de technologie supérieure (ÉTS) et qui avait pour principal objectif de quantifier et évaluer le bruit extérieur et intérieur du campus universitaire de l’ÉTS. Les étudiants devaient aussi localiser les principales sources de bruit intérieures à l’aide d’une caméra acoustique et modéliser un métamatériau acoustique qui permettra de réduire le bruit tonal émis par les transformateurs en basses fréquences.
Canadian Acoustical Association / Association canadienne d'acoustique
2023-08-24 00:00:00
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3944
Canadian Acoustics; Vol. 51 No. 2 (2023)
fre
Copyright (c) 2023 Olivier Doutres, Maël Lopez, Kévin Rouard, Louis-Philippe Campagna, Titouan Cougoulic, Anthony Jutras, David Lauzon, Pierre-Luc Pépin-Pagé, Alexis Purson
oai:jcaa.caa-aca.ca:article/3948
2023-09-12T03:21:19Z
jcaa:ART-NC
"230824 2023 eng "
2291-1391
0711-6659
dc
Assessment Of Noise In The Campus Of École De Technologie Supérieure In Montréal And Proposal Of An Acoustic Metamaterial For The Reduction Of Electrical Transformer Noise
Doutres, Olivier
École de technologie supérieure (ÉTS) https://orcid.org/0000-0003-3103-488X
Lopez, Maël
Rouard, Kevin
Campagna, Louis-Philippe
Cougoulic, Titouan
Jutras, Anthony
Lauzon, David
Pépin-Pagé, Pierre-Luc
Purson, Alexis
University campuses located in the heart of cities can be exposed to significant noise levels that can hinder the learning of students, the performance of the teaching community and staff, as well as the quality of life for residents in the neighborhood. This article presents the results of a study project conducted by students of the “Industrial Acoustics” course at École de technologie supérieure (ÉTS), with the main objective of quantifying and assessing the outdoor and indoor noise levels on the university campus. The students were also tasked with identifying the main sources of indoor noise using an acoustic camera and modeling an acoustic metamaterial that would help reduce the tonal noise emitted by transformers at low frequencies.
Canadian Acoustical Association / Association canadienne d'acoustique
2023-08-24 00:00:00
application/pdf
https://jcaa.caa-aca.ca/index.php/jcaa/article/view/3948
Canadian Acoustics; Vol. 51 No. 2 (2023)
eng
Copyright (c) 2023 Olivier Doutres