Acoustics Australia

, Volume 47, Issue 1, pp 67–77 | Cite as

Acoustic Absorption Characterization and Prediction of Natural Coir Fibers

  • Ebrahim Taban
  • Ali Tajpoor
  • Mohammad Faridan
  • Seyed Ehsan Samaei
  • Mohammad Hossein BeheshtiEmail author
Original Paper


The remarkable properties of natural lignocellulosic fibers such as biodegradability, light weight, low density, low cost and non-toxicity as well as being an alternative to sound absorbers made of synthetic fibers have attracted many researchers in the field of acoustics. The purpose of the present study was to compare the estimated sound absorption coefficient of composite samples made of natural coconut fibers by using empirical models and comparing them with the results of experimental data. The normal sound absorption coefficients of the samples were measured with an impedance tube. The samples were fabricated in three different thicknesses (25, 35 and 45 mm) with air gaps behind them and had a constant density of 200 kg/m3. Next, calculations were made to estimate the absorption coefficients of the samples by coding in MATLAB and using the differential equation algorithm along with Delany–Bazley, Miki and Johnson–Champoux–Allard models. Based on the results, the sound absorption coefficients of the samples increased significantly with increasing frequency. Additionally, increasing the thickness of materials at constant densities increases the absorption of sound, especially at lower frequencies (< 1000 Hz). Comparison of the experimental data and estimations of the models showed that by increasing thickness, the predicted acoustic absorption coefficients for the samples become closer to the data from the experimental tests. At frequencies < 1000 Hz, increasing the air gap at the back of the sample to 3 cm would elevate the values of sound absorption coefficient. The samples made of coir fibers would effectively dissipate the energy of sound waves. It is noted that increasing the absorption of the sound in such materials is related to the longer depreciation process of thermal and viscous transfer between the air and the absorbing materials in the composite.


Sound absorption coefficient Impedance tube Coir fiber Experimental models Air gap 



  1. 1.
    Amares, S., et al.: A review: characteristics of noise absorption material. In: Journal of Physics: Conference Series. IOP Publishing (2017)Google Scholar
  2. 2.
    Berardi, U., Iannace, G.: Acoustic characterization of natural fibers for sound absorption applications. Build. Environ. 94, 840–852 (2015)CrossRefGoogle Scholar
  3. 3.
    Tang, X., Yan, X.: Acoustic energy absorption properties of fibrous materials: a review. Compos. A Appl. Sci. Manuf. 101, 360–380 (2017)CrossRefGoogle Scholar
  4. 4.
    Arenas, J.P., Crocker, M.J.: Recent trends in porous sound-absorbing materials. Sound Vib. 44(7), 12–18 (2010)Google Scholar
  5. 5.
    Elwaleed, A., et al.: Experimental investigation of sound absorption properties of perforated date palm fibers panel. In: IOP Conference Series: Materials Science and Engineering. IOP Publishing (2013)Google Scholar
  6. 6.
    Iannace, G., Maffei, L., Trematerra, P.: On the use of “green materials” for the acoustic correction of classrooms. In: Proceedings of the EURONOISE (2012)Google Scholar
  7. 7.
    Yang, W., Li, Y.: Sound absorption performance of natural fibers and their composites. Sci. China Technol. Sci. 55(8), 2278–2283 (2012)CrossRefGoogle Scholar
  8. 8.
    Mamtaz, H., et al., Acoustic absorption of natural fiber composites. J. Eng. 2016, 1–11 (2016)CrossRefGoogle Scholar
  9. 9.
    Bribián, I.Z., Capilla, A.V., Usón, A.A.: Life cycle assessment of building materials: comparative analysis of energy and environmental impacts and evaluation of the eco-efficiency improvement potential. Build. Environ. 46(5), 1133–1140 (2011)CrossRefGoogle Scholar
  10. 10.
    Berardi, U., Iannace, G.: Predicting the sound absorption of natural materials: best-fit inverse laws for the acoustic impedance and the propagation constant. Appl. Acoust. 115, 131–138 (2017)CrossRefGoogle Scholar
  11. 11.
    Ayub, M., et al.: Analysis on sound absorption of natural coir fiber using Delany–Bazley model. In: Proceedings of the 8th International Conference on Mechanical Engineering (ICME2009) (2009)Google Scholar
  12. 12.
    Asdrubali, F., D’Alessandro, F., Schiavoni, S.: A review of unconventional sustainable building insulation materials. Sustain. Mater. Technol. 4, 1–17 (2015)Google Scholar
  13. 13.
    Patnaik, A., et al.: Thermal and sound insulation materials from waste wool and recycled polyester fibers and their biodegradation studies. Energy Build. 92, 161–169 (2015)CrossRefGoogle Scholar
  14. 14.
    Aksogan, O., Resatoglu, R., Binici, H.: An environment friendly new insulation material involving waste newsprint papers reinforced by cane stalks. J. Build. Eng. 15, 33–40 (2018)CrossRefGoogle Scholar
  15. 15.
    Secchi, S., et al.: Experimental and environmental analysis of new sound-absorbing and insulating elements in recycled cardboard. J. Build. Eng. 5, 1–12 (2016)CrossRefGoogle Scholar
  16. 16.
    Jayamani, E., Bakri, M.K.B.: Lignocellulosic fibres reinforced polymer composites for acoustical applications. In: Kalia, S. (ed.) Lignocellulosic Composite Materials, pp. 415–444. Springer, Berlin (2018)CrossRefGoogle Scholar
  17. 17.
    Jayamani, E., et al.: Acoustic and thermal properties of polymer composites reinforced with lignocellulosic fibers. In: Applied Mechanics and Materials. Trans Tech Publ (2014)Google Scholar
  18. 18.
    Verma, D., et al.: Coir fibre reinforcement and application in polymer composites: A. Environ. Sci. 4(2), 263–276 (2013)Google Scholar
  19. 19.
    Bettini, S., et al.: Investigation on the use of coir fiber as alternative reinforcement in polypropylene. J. Appl. Polym. Sci. 118(5), 2841–2848 (2010)CrossRefGoogle Scholar
  20. 20.
    Berardi, U., Iannace, G., Di Gabriele, M.: The acoustic characterization of broom fibers. J. Nat. Fibers 14(6), 858–863 (2017)CrossRefGoogle Scholar
  21. 21.
    Fouladi, M.H., Ayub, M., Nor, M.J.M.: Analysis of coir fiber acoustical characteristics. Appl. Acoust. 72(1), 35–42 (2011)CrossRefGoogle Scholar
  22. 22.
    Bansod, P.V., Mittal, T., Mohanty, A.R.: Study on the acoustical properties of natural jute material by theoretical and experimental methods for building acoustics applications. Acoust. Aust. 44(3), 457–472 (2016)CrossRefGoogle Scholar
  23. 23.
    Delany, M., Bazley, E.: Acoustical properties of fibrous absorbent materials. Appl. Acoust. 3(2), 105–116 (1970)CrossRefGoogle Scholar
  24. 24.
    Stelte, W., et al.: Coir fibers as valuable raw material for biofuel pellet production. Waste Biomass Valoriz. (2018). Google Scholar
  25. 25.
    Harish, S., et al.: Mechanical property evaluation of natural fiber coir composite. Mater. Charact. 60(1), 44–49 (2009)CrossRefGoogle Scholar
  26. 26.
    Islam, M.N., et al.: Physico-mechanical properties of chemically treated coir reinforced polypropylene composites. Compos. A Appl. Sci. Manuf. 41(2), 192–198 (2010)CrossRefGoogle Scholar
  27. 27.
    Limpan, N., et al.: Properties of biodegradable blend films based on fish myofibrillar protein and polyvinyl alcohol as influenced by blend composition and pH level. J. Food Eng. 100(1), 85–92 (2010)CrossRefGoogle Scholar
  28. 28.
    Egab, L., Wang, X., Fard, M.: Acoustical characterisation of porous sound absorbing materials: a review. Int. J. Veh. Noise Vib. 10(1–2), 129–149 (2014)CrossRefGoogle Scholar
  29. 29.
    Allard, J., Atalla, N.: Propagation of Sound in Porous Media: Modelling Sound Absorbing Materials 2e. Wiley, New York (2009)CrossRefGoogle Scholar
  30. 30.
    Maderuelo-Sanz, R., et al.: Acoustical performance of porous absorber made from recycled rubber and polyurethane resin. Latin Am. J. Solids Struct. 10(3), 585–600 (2013)CrossRefGoogle Scholar
  31. 31.
    Olny, X., Panneton, R.: Acoustical determination of the parameters governing thermal dissipation in porous media. J. Acoust. Soc. Am. 123(2), 814–824 (2008)CrossRefGoogle Scholar
  32. 32.
    Champoux, Y., Allard, J.F.: Dynamic tortuosity and bulk modulus in air-saturated porous media. J. Appl. Phys. 70(4), 1975–1979 (1991)CrossRefGoogle Scholar
  33. 33.
    Standard, B.: Acoustics-determination of sound absorption coefficient and impedance in impedance tubes—part 2: transfer-function method. BS EN ISO, p. 10534-2 (2001)Google Scholar
  34. 34.
    Miki, Y.: Acoustical properties of porous materials—modifications of Delany–Bazley models. J. Acoust. Soc. Jpn. E 11(1), 19–24 (1990)MathSciNetCrossRefGoogle Scholar
  35. 35.
    Allard, J.F., Champoux, Y.: New empirical equations for sound propagation in rigid frame fibrous materials. J. Acoust. Soc. Am. 91(6), 3346–3353 (1992)CrossRefGoogle Scholar
  36. 36.
    Nor, M.J.M., et al.: Effect of different factors on the acoustic absorption of coir fiber. J. Appl. Sci. 10(22), 2887–2892 (2010)CrossRefGoogle Scholar
  37. 37.
    Oliva, D., Hongisto, V.: Sound absorption of porous materials—accuracy of prediction methods. Appl. Acoust. 74(12), 1473–1479 (2013)CrossRefGoogle Scholar
  38. 38.
    Crocker, M.J.: Handbook of Noise and Vibration Control. Wiley, New York (2007)CrossRefzbMATHGoogle Scholar

Copyright information

© Australian Acoustical Society 2019

Authors and Affiliations

  • Ebrahim Taban
    • 1
  • Ali Tajpoor
    • 2
  • Mohammad Faridan
    • 3
  • Seyed Ehsan Samaei
    • 4
  • Mohammad Hossein Beheshti
    • 5
    Email author
  1. 1.Department of Occupational Health, Faculty of HealthMashhad University of Medical SciencesMashhadIran
  2. 2.Department of Occupational HealthTarbiat Modares University of Medical SciencesTehranIran
  3. 3.Department of Occupational Health, School of Health and NutritionLorestan University of Medical SciencesKhorramabadIran
  4. 4.Department of Occupational Health, Faculty of HealthMazandaran University of Medical SciencesSariIran
  5. 5.Department of Occupational Health, Faculty of Health, Social Development and Health Promotion Research CenterGonabad University of Medical ScienceGonabadIran

Personalised recommendations