Analysis of effect of thickness and surface treatment on sound transmission loss characteristics of natural fibres

Abstract Noise pollution, driven by rapid urbanisation and city expansion, has created a growing demand for innovative and bio-degradable sound absorption materials. Traditional solutions such as synthetic acoustic foams are widely used due to their efficiency and low cost but raise environmental co...

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Main Authors: Methil Vivek Shankar, N. H. Padmaraj, Sriharsha Hegde, G. M. Yash, Chandrakant R. Kini
Format: Article
Language:English
Published: Nature Portfolio 2025-08-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-14210-w
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author Methil Vivek Shankar
N. H. Padmaraj
Sriharsha Hegde
G. M. Yash
Chandrakant R. Kini
author_facet Methil Vivek Shankar
N. H. Padmaraj
Sriharsha Hegde
G. M. Yash
Chandrakant R. Kini
author_sort Methil Vivek Shankar
collection DOAJ
description Abstract Noise pollution, driven by rapid urbanisation and city expansion, has created a growing demand for innovative and bio-degradable sound absorption materials. Traditional solutions such as synthetic acoustic foams are widely used due to their efficiency and low cost but raise environmental concerns because of their non-biodegradable nature. This study explored the use of natural fibres—coir and sponge gourd—as environmentally friendly alternatives for sound insulation. The research focused on the effect of fibre thickness and surface treatment (using sodium hydroxide (NaOH)) on their acoustic performance. The Fourier Transform Infrared Spectroscopy (FTIR) technique was used to understand the effects of the treatment on the functional groups of the fibre. The surface modification of the fibre surface was studied using an optical microscope, Brumauer–Emmet–Teller (BET) analysis and by analysis of Scanning Electron Microscope (SEM) images. An impedance tube setup was used to measure the sound transmission loss for both the untreated and treated fibres. The results showed that increasing the thickness of both coir and sponge gourd fibres improves transmission loss at lower frequencies but reduces effectiveness at higher frequencies. Surface treatment had a material-dependent effect: sponge gourd fibres showed improved transmission loss due to increased surface roughness and airflow resistivity, whereas coir fibres exhibited a decline in performance after treatment. These findings contribute to a better understanding of how natural materials can be optimised for acoustic applications through structural modifications.
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spelling doaj-art-e6e192f39ca74df684e1cf34c90fcf852025-08-20T04:02:55ZengNature PortfolioScientific Reports2045-23222025-08-0115111410.1038/s41598-025-14210-wAnalysis of effect of thickness and surface treatment on sound transmission loss characteristics of natural fibresMethil Vivek Shankar0N. H. Padmaraj1Sriharsha Hegde2G. M. Yash3Chandrakant R. Kini4Department of Aeronautical and Automobile Engineering, Manipal Institute of Technology, Manipal Academy of Higher EducationDepartment of Aeronautical and Automobile Engineering, Manipal Institute of Technology, Manipal Academy of Higher EducationDepartment of Aeronautical and Automobile Engineering, Manipal Institute of Technology, Manipal Academy of Higher EducationDepartment of Aeronautical and Automobile Engineering, Manipal Institute of Technology, Manipal Academy of Higher EducationDepartment of Aeronautical and Automobile Engineering, Manipal Institute of Technology, Manipal Academy of Higher EducationAbstract Noise pollution, driven by rapid urbanisation and city expansion, has created a growing demand for innovative and bio-degradable sound absorption materials. Traditional solutions such as synthetic acoustic foams are widely used due to their efficiency and low cost but raise environmental concerns because of their non-biodegradable nature. This study explored the use of natural fibres—coir and sponge gourd—as environmentally friendly alternatives for sound insulation. The research focused on the effect of fibre thickness and surface treatment (using sodium hydroxide (NaOH)) on their acoustic performance. The Fourier Transform Infrared Spectroscopy (FTIR) technique was used to understand the effects of the treatment on the functional groups of the fibre. The surface modification of the fibre surface was studied using an optical microscope, Brumauer–Emmet–Teller (BET) analysis and by analysis of Scanning Electron Microscope (SEM) images. An impedance tube setup was used to measure the sound transmission loss for both the untreated and treated fibres. The results showed that increasing the thickness of both coir and sponge gourd fibres improves transmission loss at lower frequencies but reduces effectiveness at higher frequencies. Surface treatment had a material-dependent effect: sponge gourd fibres showed improved transmission loss due to increased surface roughness and airflow resistivity, whereas coir fibres exhibited a decline in performance after treatment. These findings contribute to a better understanding of how natural materials can be optimised for acoustic applications through structural modifications.https://doi.org/10.1038/s41598-025-14210-wSustainable materialsFibre treatmentSound absorptionSodium hydroxideNatural fibres
spellingShingle Methil Vivek Shankar
N. H. Padmaraj
Sriharsha Hegde
G. M. Yash
Chandrakant R. Kini
Analysis of effect of thickness and surface treatment on sound transmission loss characteristics of natural fibres
Scientific Reports
Sustainable materials
Fibre treatment
Sound absorption
Sodium hydroxide
Natural fibres
title Analysis of effect of thickness and surface treatment on sound transmission loss characteristics of natural fibres
title_full Analysis of effect of thickness and surface treatment on sound transmission loss characteristics of natural fibres
title_fullStr Analysis of effect of thickness and surface treatment on sound transmission loss characteristics of natural fibres
title_full_unstemmed Analysis of effect of thickness and surface treatment on sound transmission loss characteristics of natural fibres
title_short Analysis of effect of thickness and surface treatment on sound transmission loss characteristics of natural fibres
title_sort analysis of effect of thickness and surface treatment on sound transmission loss characteristics of natural fibres
topic Sustainable materials
Fibre treatment
Sound absorption
Sodium hydroxide
Natural fibres
url https://doi.org/10.1038/s41598-025-14210-w
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AT sriharshahegde analysisofeffectofthicknessandsurfacetreatmentonsoundtransmissionlosscharacteristicsofnaturalfibres
AT gmyash analysisofeffectofthicknessandsurfacetreatmentonsoundtransmissionlosscharacteristicsofnaturalfibres
AT chandrakantrkini analysisofeffectofthicknessandsurfacetreatmentonsoundtransmissionlosscharacteristicsofnaturalfibres