Browsing by Subject "Sound absorption"

Now showing 1 - 5 of 5

Open Access
3D Labyrinthine-type acoustical metamaterial proposals for sound control in architectural applications
(Institute of Noise Control Engineering(INCE), 2019-06) Yazıcı, Beyza; Gül, Zühre Sü
The purpose of this research is to develop alternative 3D labyrinthine-type acoustical metamaterials by utilizing 'space-coiling' for sound control in architectural applications. Acoustical metamaterials have a great potential on their application for building and room acoustics due to their extreme properties in sound absorption and transmission. They can be used as an interior partition, an interior surface layer, and also as a design element. They are advantageous in comparison to the traditional acoustical materials such that by tuning their physical properties more hygienic, lighter or thinner alternatives can be produced. In this research, the design ideas of acoustic metamaterials (AMMs) originate from golden ratio (GR) and web labyrinth (WL). In data collection and analysis, both experimental and theoretical methods are used. As a first step, all design alternatives are modelled in 3D, then are printed out by a CNC 3D printer, finally, the AMMs are tested in impedance tube to observe their acoustical properties. Initial results indicate that WL shows good performance in terms of transmission loss and GR has efficiency for sound absorption in low frequency range. Both options are better than Solid sample. The results indicate the potential of designed alternatives and are supportive for future optimization.
Open Access
Biomimetic acoustic metamaterial design for architectural applications
(2020-08) Yazıcı, Beyza
This study investigates the potentials of acoustic metamaterial (AMM) applications in room and building acoustics by means of impedance tube experiments. With their extreme properties in either sound absorption or transmission loss, AMMs can perform better than many traditional acoustic materials in buildings. Importantly, they are also more sustainable and hygienic than ﬁbrous and porous materials. Depending on the matrix material used, AMMs can vary in transparency and color. Considering both their acoustic and aesthetic values, this study develops diﬀerent types of metamaterial for possible uses as a partition wall, a surface layer, or a design element. The proposed metamaterials are primarily based on the exploration of ratios and forms from nature – the golden ratio, web-labyrinthine structures, genetic and neural systems such as DNA molecules and the synapse structures in the brain – reproduced on a sub-wavelength scale. These abstractions are then combined with the 3D space coiling and 3D labyrinth approaches of AMM design. Modules of the proposed AMMs are manufactured in a 3D printer and tested in an impedance tube to estimate their normal incidence sound absorption coeﬃcients and transmission loss characteristics. Based on the results obtained, the modules with the higher performances are used in the design of partition walls of varying heights. Two real-case architecture studios are simulated with and without the proposed AMM interventions over ﬁeld test-tuned acoustical models of the studios to assess the eﬀectiveness of such an approach in a possible acoustical design problem.
Open Access
Biomimetic metamaterial design simulation and evaluation for building acoustics by impedance measurements
(A S T M International, 2021-09-01) Yazıcı, Beyza; Gül, Zühre Sü
This study investigates the potentials of acoustic metamaterial (AMM) applications in room and building acoustics by means of impedance tube experiments. With their extreme properties in either sound absorption or transmission loss, AMMs can perform better than traditional acoustic materials in buildings. Importantly, they are also more sustainable and hygienic than fibrous and porous materials. Depending on the matrix material used, AMMs can vary in transparency and color. Considering both their acoustic and aesthetic values, this study develops different types of metamaterial for possible uses as a partition wall, a surface layer, or a design element. The proposed metamaterials are primarily based on the exploration of ratios and forms from nature—the golden ratio, web-labyrinthine structures, genetic and neural systems such as deoxyribonucleic acid (DNA) molecules, and the synapse structures in the brain—reproduced on a subwavelength scale. These abstractions are then combined with the 3-D space coiling and 3-D labyrinth approaches of AMM design. Modules of the proposed AMMs are manufactured in a 3-D printer and tested in an impedance tube to estimate their normal incidence sound absorption coefficients and transmission loss characteristics. Based on the results obtained, the modules with the higher performances are used in the design of partition walls of varying heights. Two real-case architecture studios are simulated with and without the proposed AMM interventions over field test–tuned acoustical models of the studios to assess the effectiveness of such an approach in a possible acoustical design problem.
Open Access
Developing wideband acoustic absorbers in interior spaces: modelling, measurements and applications
(2024-01) Fasllija, Ela
This study aims to develop wideband acoustic absorbers in interior spaces for speech purposes, through the use of Micro-Perforated Panels (MPPs) arranged in different configurations. The research has involved theoretical modelling, measurements, and applications in interior spaces. The initial phase focused on modelling various MPP arrangements and predicting their sound absorption coefficients using the Electric Equivalent Circuit Model (ECM) under normal and oblique incidence conditions. Small samples with different geometric parameters were then manufactured and tested for their absorption coefficients at the Turkish Standards Institute, following the impedance tube method (ISO 10534-2:1998). The preliminary results showed a good agreement with the numerical predictions. Furthermore, the random incidence absorption coefficient of a parallel arranged MPP structure was measured in a Small-Scale Reverberation Room (SSRR) at Bilkent University to evaluate the proposed structure in a diffuse field. The results obtained by using ISO 354:2003 showed lower values than the predicted ones by a range of 0.1- 0.3. However, there was a better alignment between the ECM predictions and experimental results for 30-degree oblique incidence. Regarding interior applications, a classroom with poor acoustics was treated in ODEON 16 using the proposed material in the form of a wall panel. The effect of the developed material on objective room acoustics parameters was examined, revealing improvements in the Reverberation Time and Speech Intelligibility Index values. Lastly, the Turkish versions of Perceived Affective Qualities outlined in the ISO/TS 12913-2:2018 standard were developed to assess the subjective perception of the material following the soundscape approach.
Open Access
Sound absorption coefficient changes of acoustical plates made of expanded perlite in moist environment
(WITPress, 2003) Yılmazer, Semiha
Expanded perlite is a porous, lightweight, fire resistant and moisture retaining material with sound and thermal insulation properties. In this research, acoustical behaviour of plates made of expanded perlite was studied experimentally. Since these plates are used for sound absorption the acoustical parameter selected for this study is "sound absorption coefficient". Preliminary experiments indicated that moisture reduced the sound absorption coefficient on plates and there is not much significant difference between the dry and 50% humid conditions. However, there is a significant difference in acoustical properties for the 50% - 95% humid conditions. Thus, this interval was studied in detail. A number of expanded perlite plates having different mixtures were prepared and tested. It was observed that coating of expanded perlite particles with sodium silicate increased moisture resistance, and that the addition of mineral fibre into the mixtures increased the strength and sound absorption coefficient of the plates.