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Improving Sound Transmission Through Triple-Panel Structure Using Porous Material and Sonic Crystal

Myong-Jin Kim

Archives of Acoustics | 2019 | vol. 44 | No 3 | 533-541 | DOI: 10.24425/aoa.2019.129268

Keywords sound transmission loss sonic crystal triple-panel structure sound insulation

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Abstract

Main aim of this study is to combine the characteristics of the sonic crystal (SC) with acoustic panels and porous materials to improve the sound transmission loss (STL) through the triple-panel structure. SCs cause a bandgap centered around a certain frequency (Bragg’s frequency) due to generation of destructive interference. Initially, an analytical method is developed that extends the previous theory of double-panel structure to predict STL through a triple-panel structure. Finite element (FE) simulations are performed to obtain the STL through the triple-panel, which are validated with the analytical predictions. Various configurations are analyzed using the FE method based on the method of inserting the porous material and SCs between the panels to address the combined effect. STL through the triple-panel structure is compared with that through the double-panel structure having the same total weight and total thickness. It is found that the combined structure of the triple panel and the SC with glass wool as filler gives the best soundproof performance for the same external dimensions. For narrow air gaps, filing with glass wool is more advantageous than inserting one row of SC. In addition, the triple panel combined with a SC has better soundproofing than the two-panel counterparts.

Authors and Affiliations

Myong-Jin Kim

Relationship Between the Sound Transmission Through the Finite Double-Panel Structure with a Cylindrical Shell Array and the Vibro-Acoustic Characteristics of its Constituents

Song-Hun Kim Myong-Jin Kim

Archives of Acoustics | 2023 | vol. 48 | No 3 | 381-388 | DOI: 10.24425/aoa.2023.145244

Keywords sound transmission loss double-panel structure eigenmode vibration sonic crystal

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Abstract

Sound insulation of the finite double-panel structure (DPS) inserted with a cylindrical shell array is investigated by varying the sound incidence direction to improve its applicability. The effects of the vibro-acoustic characteristics of its constituents on the sound transmission loss (STL) are estimated in one-third octave bands from 20 Hz to 5 kHz for different incidence conditions. It shows that the first acoustic mode in the direction parallel to two panels (longitudinal modes) produces both the sudden variation of sound insulation with frequency and a large dependency on the incidence angle. Mineral wools are placed on two boundaries perpendicular to the panels, and the sound insulation is explored for different thicknesses of the porous materials. An absorbent layer with a certain thickness (more than 30 mm in our work) sufficiently eliminates the longitudinal mode, resulting in the improvement in the sound insulation by more than 15 dB and the decrease of its large variation with incidence direction. STLs with varying shell thicknesses are also assessed. It shows that the natural vibrations of the thin shells can give an enhancement in sound insulation by more than 10 dB in the frequency range of 1600–3700 Hz, corresponding to constructive interference.

Authors and Affiliations

Song-Hun Kim

1

Myong-Jin Kim

1

Institute of Acoustics, Department of Physics, Kim Il Sung University, Pyongyang, Democratic People’s Republic of Korea

2D Modeling of Wave Propagation in Shallow Water by the Method of Characteristics

Mohammad Reza Khalilabadi

Archives of Acoustics | 2022 | vol. 47 | No 3 | 407-412 | DOI: 10.24425/aoa.2022.142014

Keywords wave propagation shallow water MOC method waveguide transmission loss

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Abstract

In this paper, a 2D numerical modeling of sound wave propagation in a shallow water medium that acts as a waveguide, are presented. This modeling is based on the method of characteristic which is not constrained by the Courant–Friedrichs–Lewy (CFL) condition. Using this method, the Euler time-dependent equations have been solved under adiabatic conditions inside of a shallow water waveguide which is consists of one homogeneous environment of water over a rigid bed. In this work, the stability and precision of the method of characteristics (MOC) technique for sound wave propagation in a waveguide were illustrated when it was applied with the semi-Lagrange method. The results show a significant advantage of the method of characteristics over the finite difference time domain (FDTD) method.

Authors and Affiliations

Mohammad Reza Khalilabadi

1

Faculty of Naval Aviation, Malek Ashtar University of Technology, Iran

Influence of Geometric Structure, Convection, and Eddy on Sound Propagation in Acoustic Metamaterials with Turbulent Flow

Myong Chol Pak Kwang-Il Kim Hak Chol Pak Kwon Ryong Hong

Archives of Acoustics | 2021 | vol. 46 | No 4 | 637-647 | DOI: 10.24425/aoa.2021.139640

Keywords acoustic metamaterial turbulent flow sound transmission loss eddy transportation

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Abstract

The problem of reducing noise in transportation is an important research field to prevent accidents and to provide a civilised environment for people. A material that has recently attracted attention in research to reduce noise is acoustic metamaterial, and most of the research projects so far have been limited to the case of static media without flow. We have studied the sound transmission properties of the acoustic metamaterials with turbulent flow to develop the acoustic metamaterials that are used in transportation. In this paper, the effects of geometrical structure, convection, and eddy on sound propagation in the acoustic metamaterials with turbulent flow are investigated, and the relationships between them are analysed. The effects of convection and eddy reduce the resonant strength of the sound transmission loss resulting from the unique geometry of the acoustic metamaterials, but move the resonant frequencies to opposite directions. In addition, when the convective effect and the eddy effect of the airflow, as well as the intrinsic interaction effect generated from the unique geometrical structure of the acoustic metamaterials cannot be ignored, they exhibit competition phenomena with each other, resulting in a widening of the resonance peak. As a result, these three effects cause the shift of the resonance frequency of the sound transmission loss and the widening of the resonance peak. The results of this study show that even in the case of turbulent flow, the metamaterials can be used for transportation by properly controlling its geometric size and shape.

Bibliography

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Authors and Affiliations

Myong Chol Pak

1

Kwang-Il Kim

1

Hak Chol Pak

1

Kwon Ryong Hong

2

Department of Physics, Kim Il Sung University, Taesong District, Pyongyang, Democratic People’s Republic of Korea
Institute of Natural Sciences, Kim Il Sung University, Taesong District, Pyongyang, Democratic People’s Republic of Korea

Effect of Emergence Angle on Acoustic Transmission in a Shallow Sea

Yanyang Lu Kunde Yang Hong Liu Chunlong Huang

Archives of Acoustics | 2020 | vol. 45 | No 1 | 3-9 | DOI: 10.24425/aoa.2019.129736

Keywords underwater acoustic emergence angle transmission loss active sonar detection

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Abstract

In this study, the effect of the emergence angle of a source array on acoustic transmission in a typical shallow sea is simulated and analyzed. The formula we derived for the received signal based on the Normal Mode indicates that the signal is determined by the beamform on the modes of all sources and the samplings of all modes at the receiving depth. Two characteristics of the optimal emergence angle (OEA) are obtained and explained utilizing the aforementioned derived formula. The observed distributions of transmission loss (TL) for different sources and receivers are consistent with the obtained characteristics. The results of this study are valuable for the development and design of active sonar detection.

Authors and Affiliations

Yanyang Lu

Kunde Yang

Hong Liu

Chunlong Huang

Analysis of the influencing factors of the acoustic performance of the muffler considering acoustic structural coupling

Bo Zhao He Li

Archives of Acoustics | 2022 | vol. 47 | No 4 | 479-490 | DOI: 10.24425/aoa.2022.142900

Keywords acoustic performance muffler acoustic-structural coupling transmission loss mode optimisation

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Abstract

In the calculation of the acoustic performance of mufflers, the walls of mufflers are usually treated rigidly without considering the acoustic-structural coupling, but the results so calculated differ significantly from the actual situation. Based on the basic equations, the article derives the finite element equations of the muffler system while considering the acoustic-structural coupling effect and theoretically analyses the connection between the acoustic-structural coupling system and the structural and acoustic modes. The structural and acoustic modes of the muffler are calculated and the reasons for the mutation of the transmission loss curve of the muffler when the acoustic-structural coupling is considered are analysed. The results show that the acoustic-structural coupling is the result of the interaction between the structure and the air inside the expansion chamber under acoustic excitation, which manifests mutations in the sound pressure inside the muffler in some frequency bands. Then, using a single-chamber muffler as an example, the transmission loss is used to characterise the performance of the muffler. The effects of different factors such as shell thickness, structure, porous media material lining, and restraint method on the acoustic-structural coupling effect of the muffler are analysed, and the structure of a double-chamber muffler is successfully optimised according to the conclusions.

Authors and Affiliations

Bo Zhao

1

He Li

1

School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110819, China

Trade based on alliance chain in energy from distributed photovoltaic grids

Ran Ding Chaohan Feng Dongsheng Wang Rongfu Sun Longyang Wang Shaojun Yuan

Archives of Electrical Engineering | 2021 | vol. 70 | No 2 | 325-366

Keywords alliance chain distributed photovoltaic grid power transmission loss pricing strategy

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Abstract

With the rapid development of distributed photovoltaic grids, more and more users join the power sales side, and the traditional power grid operation mode is no longer applicable. This paper analyzes the characteristics of the distributed photovoltaic grid under overload conditions, and further summarizes the problems that the distributed photovoltaic grid will face under these conditions. To solve these problems, the alliance chain technology was introduced into the distributed photovoltaic grid.At the same time, this paper establishes a photovoltaic pricing strategy that considers power transmission loss. Finally, the feasibility of the theory is verified by constructing a virtual model.

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Authors and Affiliations

Ran Ding

1

Chaohan Feng

1

Dongsheng Wang

1

Rongfu Sun

1

Longyang Wang

2

Shaojun Yuan

3

Dispatch Center, State Grid Jibei Electric Power Company, 56 Caishikou South Street, Xicheng District, Beijing, China
School of Mechanical and Electronic Engineering, Wuhan University of Technology, China
Chengde Power Supply Company, China

Analysis and Modelling on Radiated Noise of a Typical Fishing Boat Measured in Shallow Water Inspired by AQUO Project’s Model

Peng Zilong Fan Jun Wang Bin

Archives of Acoustics | 2018 | vol. 43 | No 2 | DOI: 10.24425/122374

Keywords radiated noise South China Sea predicted model shallow water transmission loss

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Abstract

The shipping noise near channels and ports is an important contribution to the ambient noise level, and the depth of these sites is often less than 100 m. However less attention has been paid to the measurement in shallow water environments (Brooker, Humphrey, 2016). This paper presents extensive measurements made on the URN (underwater radiated noise) of a small fishing boat in the South China Sea with 87 m depth. The URN data showed that the noise below 30 Hz was dominated by the background noise. The transmission loss (TL) was modelled with FEM (finite element method) and ray tracing according to the realistic environmental parameters in situ. The discrepancy between the modelled results and the results using simple law demonstrates both sea surface and bottom have significant effect on TL for the shallow water, especially at low frequencies. Inspired by the modelling methodology in AQUO (Achieve QUieter Oceans) project (Audoly et al., 2015), a predicted model applied to a typical fishing boat was built, which showed that the URN at frequencies below and above 100 Hz was dominated by non-cavitation propeller noise and mechanical noise, respectively. The agreement between predicted results and measured results also demonstrates that this modelling methodology is effective to some extent.

Authors and Affiliations

Peng Zilong

Fan Jun

Wang Bin

Selection of Plate Components of Operator's Cabin Walls in Aspect of Thermal Insulation and Transmission Loss

Zygmunt Dziechciowski

Archives of Acoustics | 2011 | vol. 36 | No 1 | 109-119 | DOI: 10.2478/v10168-011-0012-1

Keywords acoustic and thermal comfort heavy-duty machine cabin transmission loss thermal insulation

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Abstract

The modern cabin of heavy duty machines have to fulfil a number of requirements which deal with operators' work comfort. More and more often, the vibroacoustic and thermal comforts decide about the cabin quality. This paper presents principles of acoustic and thermal calculations as well as their use in combined assessment.

Authors and Affiliations

Zygmunt Dziechciowski

Acoustic Attenuation Performance Analysis and Optimisation of Expansion Chamber Coupled Micro-perforated Cylindrical Panel Using Response Surface Method

Mohamad Izudin Alisah Lu-Ean Ooi Zaidi Mohd Ripin Ahmad Fadzli Yahaya Kelvin Ho

Archives of Acoustics | 2021 | vol. 46 | No 3 | 507-517 | DOI: 10.24425/aoa.2021.138143

Keywords micro-perforated cylindrical panel transmission loss boundary element method response surface method

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Abstract

This paper describes boundary element method (BEM), experimental and optimization studies conducted to understand the potential of expansion tube coupled micro-perforated cylindrical panel (MPCP) to enhance the acoustic attenuation for in-duct noise control issues. Due to complex structure of the MPCP and for the correct prediction of acoustic attenuation, BEM is adopted on the basis of PLM Simcenter 3D software to compute the sound transmission loss (TL). As the MPCP is cylindrical in-shape with numbers of sub-milimeter holes, additive manufacturing based 3D printing was utilized for the model prototyping to reduce current design limitation and enabled fast fabrication. The TL measurement based two-load method is adopted for modal validation. Subsequently, a parametric studies of the MPCP concerning the perforation hole diameter, perforation ratio and depth of air space are carried out to investigate the acoustical performance. Optimization via response surface method (RSM) is used as it allows evaluating the effects of multiple parameters as required in this study. The model validation result shows that the error between the BEM and and measured values is relatively small and show a good agreement. The R-square value is 0.89. The finding from parametric study shows that a widen peak attenuation can be achieve by reducing the perforation hole diameter and one way to increase the transmission loss amplitude is by increasing the air cavity depth. Finally, the optimized MPCP model was adopted to the commercial vacuum cleaner for the verification. The sound pressure level (SPL) of the vacuum cleaner is significantly attenuated within the objective frequency of 1.7 kHz and its A-weighted SPL is reduced by 1.8 dB.

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Authors and Affiliations

Mohamad Izudin Alisah

1

Lu-Ean Ooi

1

Zaidi Mohd Ripin

1

Ahmad Fadzli Yahaya

2

Kelvin Ho

2

The Vibration Lab, School of Mechanical Engineering, Engineering Campus, Universiti Sains Malaysia,14300 Nibong Tebal, Pulau Pinang, Malaysia
Dyson Manufacturing, 81400 Senai, Johor, Malaysia

The Effect of Cold Eddy on Acoustic Propagation (Case Study: Eddy in the Persian Gulf)

Omid Mahpeykar Amir Ashtari Larki Mohammad Akbari Nasab

Archives of Acoustics | 2022 | vol. 47 | No 3 | 413-423 | DOI: 10.24425/aoa.2022.142015

Keywords Persian Gulf cold eddy transmission loss (TL) acoustic propagation BELLHOP model

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Abstract

It is essential for oceanographers to study the effects of marine phenomena such as currents, surface mixed layer, eddies, internal waves, and other ocean features on acoustic propagation, as most marine measurement equipment operates on this basis, like sonar. The eddy impact on acoustic transmission in the marine environment is very significant because changes in temperature and salinity disrupt the sound speed due to the presence of eddy, thus the acoustic propagation in the sea. Although cold eddies are in the Persian Gulf widely, one eddy is selected to study their impacts on acoustic propagation because they have similar properties in terms of temperature and salinity. In this research, after identifying eddies in the Persian Gulf automatically, the effect of a cold eddy on acoustic propagation was investigated at different depths using the BELLHOP model. Most eddies are cyclonic with 5–10 km of radius based on algorithm outputs. Studies on the lifespan of eddies showed that the occurrence of cyclonic eddies with a lifespan of more than three days is more than anticyclonic ones. Examination of the eddy effect on acoustic propagation showed that the transmission loss (TL) during the progress of the acoustic wave across the eddy increases with increasing the depth of the sound source. Also, the presence of cold eddy compared to the conditions it does not exist increases the transmission loss. The study of three-dimensional acoustic propagation also confirmed the obtained results in two-dimensional mode and clearly showed the role of cold eddy in increasing the TL.

Authors and Affiliations

Omid Mahpeykar

1

Amir Ashtari Larki

1

Mohammad Akbari Nasab

2

Department of Physical Oceanography, Faculty of Marine Science and Oceanography, Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran
Department of Marine Physics, Faculty of Marine and Oceanic Sciences, University of Mazandaran, Babolsar, Iran

Evaluation of the Effect of Uncertainties on the Acoustic Behavior of a Porous Material Located in a Duct Element Using the Monte Carlo Method

Hanen Hannachi Hassen Trabelsi Marwa Kani Mohamed Taktak Mabrouk Chaabane Mohamed Haddar

Archives of Acoustics | 2023 | vol. 48 | No 1 | 81-91 | DOI: 10.24425/aoa.2023.144266

Keywords porous material physical parameters transmission loss acoustic power attenuation Monte Carlo method

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Abstract

When studying porous materials, most acoustical and geometrical parameters can be affected by the presence of uncertainties, which can reduce the robustness of models and techniques using these parameters. Hence, there is a need to evaluate the effect of these uncertainties in the case of modeling acoustic problems. Among these evaluation methods, the Monte Carlo simulation is considered a benchmark for studying the propagation of uncertainties in theoretical models. In the present study, this method is applied to a theoretical model predicting the acoustic behavior of a porous material located in a duct element to evaluate the impact of each input error on the computation of the acoustic proprieties such as the reflection and transmission coefficients as well as the acoustic power attenuation and the transmission loss of the studied element. Two analyses are conducted; the first one leads to the evaluation of the impacts of error propagation of each acoustic parameter (resistivity, porosity, tortuosity, and viscous and thermal length) through the model using a Monte Carlo simulation. The second analysis presents the effect of propagating the uncertainties of all parameters together. After the simulation of the uncertainties, the 95% confidence intervals and the maximum and minimum errors of each parameter are computed. The obtained results showed that the resistivity and length of the porous material have a great influence on the acoustic outputs of the studied model (transmission and reflection coefficients, transmission loss, and acoustic power attenuation). At the same time, the other physical parameters have a small impact. In addition, the acoustic power attenuation is the acoustic quantity least impacted by the input uncertainties.

Authors and Affiliations

Hanen Hannachi

1 2

Hassen Trabelsi

1

Marwa Kani

1 2

Mohamed Taktak

3 4

Mabrouk Chaabane

2

Mohamed Haddar

2

Laboratory of Mechanics, Modeling and Productivity (LA2MP), National School of Engineers of Sfax, University of Sfax, Sfax, Tunisia
Faculty of Science of Sfax, University of Sfax, Sfax, Tunisia
Laboratory of Mechanics, Modeling and Productivity (LA2MP), National School of Engineers of Sfax, University of Sfax, Tunisia
Faculty of Sciences of Sfax, University of Sfax, Tunisia

An Improved MSA Model for Evaluating the Sound Transmission Loss of a Rectangular Plate for Diffuse Field Incidence

Myong-Jin Kim Kyong-Su Won Chol-Su Ri

Archives of Acoustics | 2019 | vol. 44 | No 2 | 259-265 | DOI: 10.24425/aoa.2019.128489

Keywords transmission loss low frequency range natural vibration mode diffuse field incidence

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Abstract

This paper presents an approximate analytical model for estimating the transmission loss (TL) of a finite rectangular plate in the low frequency range, which is based on the modal summation approach (MSA) taking into account the modal radiation impedance and fluid loading. The mode-dependent radiation resistance is calculated using the Rayleigh integral. The fluid loading is taken into account through the natural frequency modified by the added mass. The results are compared with the ones of Statistical Energy Analysis (SEA) coupled with FEM and FEM coupled with BEM. In addition, the effects of the various vibration modes and the fluid loading on TL, and a way for reducing the calculation time are discussed.

Authors and Affiliations

Myong-Jin Kim

Kyong-Su Won

Chol-Su Ri

Broadening Low-Frequency Band Gap of Double-Panel Structure Using Locally Resonant Sonic Crystal Comprised of Slot-Type Helmholtz Resonators

Myong-Jin Kim Chun-Gil Rim Kyong-Su Won

Archives of Acoustics | 2021 | vol. 46 | No 2 | 335-340 | DOI: 10.24425/aoa.2021.136587

Keywords sound transmission loss locally resonant sonic crystal double-panel structure sound insulation

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Abstract

An approach is presented to form and broaden the low-frequency band gap of the double panel structure (DPS) by using a locally resonant sonic crystal (LRSC) in this work. The LRSC is made of cylindrical Helmholtz resonators arranged on square lattice. Their designs are similar to a slot-type resonator, but have different depths of slot. Elongating the slit neck inward and distributing the depths of slots produce a broad local resonant band gap at low frequencies: an average insertion loss (IL) of 10.9 dB covering 520 Hz to 1160 Hz with a LRSC of 12 cm width. Next, the effect of porous material filled into the resonators on the local resonant band gap is evaluated. It is shown that filling of porous material into the resonators decreases the height and width of the local resonant band gap. Finally, the transmission losses (TLs) through the DPS with LRSC are calculated as a function of the incident angle of the sound wave for LRSC embedded in porous material and not. The results show that the porous material can be significantly reduce the incident angle dependency of TL through the DPS with LRSC.

Authors and Affiliations

Myong-Jin Kim

1

Chun-Gil Rim

1

Kyong-Su Won

1

Institute of Acoustics, Department of Physics, Kim Il Sung University, Pyongyang, Democratic People’s Republic of Korea

Analytical and computational acoustic modelling of side outlet muffler and its extension in the modelling of tapered side outlet

Sandeep Kumar Vishwakarma Suryappa Jayappa Pawar

Archives of Acoustics | 2022 | vol. 47 | No 4 | 491-499 | DOI: 10.24425/aoa.2022.142893

Keywords 1-D analysis FEA sound pressure level transfer matrix transmission loss

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Abstract

Mufflers are popular in the suppression of noise levels coming from various machinery. The most common parameters for the evaluation of the performance of mufflers are transmission loss, noise level, and insertion loss. The transmission loss is evaluated for tapered side outlet muffler using finite element analysis without considering the fluid-structure interaction. This study includes analytical modelling and acoustic modelling of the side outlet muffler and transmission loss is in excellent agreement with the reference paper. The feasibility of the acoustic model is also verified with the experimental work on simple expansion chamber muffler. The same finite element analysis is extended for the tapered side outlet muffler. The transmission loss of the tapered side outlet muffler in the given frequency range is found 8.96 dB better than the side outlet muffler. The acoustic pressure level and sound pressure level contours for the tapered side outlet muffler give a clear picture of wave propagation inside the muffler. The effect of the cut-off frequency on the transmission loss of the tapered side outlet muffler can be seen from the contours. This study can be helpful in the determination of the performance of the mufflers in terms of transmission loss, the performance of mufflers above cut-off frequency, and design improvements in the muffler to avoid the higher-order modes of the sound wave.

Authors and Affiliations

Sandeep Kumar Vishwakarma

1

Suryappa Jayappa Pawar

1

e-mail:

ORCID:

Department of Applied Mechanics, Motilal Nehru National Institute of Technology Allahabad, Prayagraj, India

Research on the Performance Optimization of Turbulent Self-Noise Suppression and Sound Transmission of Acoustic Windows Made from Functionally Graded Material

Bing Li Fu-Lin Zhou Jun Fan Bin Wang Li-Wen Tan

Archives of Acoustics | 2023 | vol. 48 | No 4 | 475-495 | DOI: 10.24425/aoa.2023.146812

Keywords functionally graded material acoustic window turbulent self-noise sound transmission loss optimization

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Authors and Affiliations

Bing Li

1

Fu-Lin Zhou

1

Jun Fan

1

Bin Wang

1

e-mail:

ORCID:

Li-Wen Tan

1

Key Laboratory of Marine Intelligent Equipment and System, Ministry of Education, P.R. China

Generation of two identical ns laser pulses at single s spacing by switching output mirror transmission

Marek Skórczakowski Waldemar Żendzian Zdzisław Jankiewicz

Metrology and Measurement Systems | 2020 | vol. 27 | No 3 | 513-530 | DOI: 10.24425/mms.2020.132783

Keywords double pulse Q-switched laser pulsed holographic interferometry transmission losses switching diode pumped Q-switched laser

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Abstract

Generation of two identical ns laser pulses spaced by a single µs time interval by means of sequential switching of the output mirror transmittance in a diode-pumped Nd:YAG laser is reported, to our knowledge, for the first time. The theoretical study of the process of transmission losses switching is developed. This analysis confirms the possibility of generation of two identical Q-switched laser pulses with 100% efficiency with respect to the referenced single pulse energy. The detailed characterization of the laser in free-running, single and double Q-switching regimes is presented. The laser can be applied in different branches of metrology as PIV, LIBS or holographic interferometry.

Authors and Affiliations

Marek Skórczakowski

Waldemar Żendzian

Zdzisław Jankiewicz

Technical Notes: Practical Concerns Associated with Single-Number Ratings in Measuring Sound Transmission Loss Properties of Partition Panels

Naveen Garg Anil Kumar Sagar Maji

Archives of Acoustics | 2013 | vol. 38 | No 1 | 115-124 | DOI: 10.2478/aoa-2013-0014

Keywords Sound Transmission Loss (TL) sound transmission class (STC) spectrum adaptation terms (C; Ctr) ISO 717-1 weighted sound reduction index (Rw) spectrum adaptation term corresponding to noise source Cx

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Abstract

The paper presents an extensive review investigating the practical aspects related to the use of single- number ratings used in describing the sound insulation performance of partition wall panels and practical complications encountered in precise measurements in extensive frequency range from 50 Hz to 5 kHz. SWOT analysis of various single number ratings is described. A laboratory investigation on a double wall partition panel combination revealed the significant dependence of STC rating on transmission loss at 125 Hz attributed to 8 dB rule. An investigation conducted on devising alternative spectrums of aircraft noise, traffic noise, vehicular horn noise and elevated metro train noise as an extension to ISO 717-1 Ctr for ascertaining the sound insulation properties of materials exclusively towards these noise sources revealed that the single-number rating Rw + Ctr calculated using ISO 717-1 Ctr gives the minimum sound insulation, when compared with Rw + Cx calculated using the alternative spectrums of aircraft noise, traffic noise, etc., which means that material provides a higher sound insulation to the other noise sources. It is also observed that spectrum adaptation term Cx calculated using the spectrum of noise sources having high sound pressure levels in lower frequencies decreases as compared to ISO 717-1 Ctr owing to significant dependence of Ctr at lower frequencies.

Authors and Affiliations

Naveen Garg

Anil Kumar

Sagar Maji

1

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