Comparison of acoustic absorption characteristics of coir and date palm fibers: experimental and analytical study of green composites

Abstract

The use of natural biodegradable fibers in manufacturing of porous sound absorbers is an environmental-friendly approach employed by many researchers in the field of noise control and acoustics. The present study aimed to determine and compare the sound absorption coefficients of samples fabricated from fibers of coir and date palm by experimental and analytical methods. Experimental measurements of the sound absorption coefficients were performed in an impedance tube by modifying several parameters (thickness and air gap) of the samples. Prediction of sound absorption coefficient was determined by Delany-Bazley, Miki and Johnson-Champoux-Allard models along with differential evolution algorithm in MATLAB software and data from the experiments. The correlation between the sound absorption coefficients obtained from the experiments and the ones predicted by the existing models was examined by the Pearson correlation test. Samples from both type of fibers showed a poor and almost similar sound absorption in low-frequency range. In intermediate range (1000-3000 Hz), the sound absorption significantly increased to the maximum levels of 0.81 and 0.84 at 2000 Hz for the thickness of 40 mm. An increase in the samples thickness led to a fair agreement between values of sound absorption coefficient obtained from experimental and analytical methods. Correlation analysis showed that there was a significant and strong correlation between the outputs from the existing models and the experiments. The values approximated by Johnson-Champoux-Allard model demonstrated a better fit with the ones determined by the experimental tests.

Acoustic Panels Made of Paper Sludge and Clay Composites

“…In 1/3 octave band spectra, other middle frequencies are calculated by multiplying or dividing by 2 1/3 . The lower and higher frequency bounds are calculated according to Equations (6) and (7) [39]. The sound absorption values in each one-third octave band were averaged.…”

“…Such goals create motivation to look for a new environmentally friendly alternatives for noise control. Numerous studies are concerned about the acoustic properties of recycled tire rubber, wood chip, foam, plastics and natural fibres [2][3][4][5][6][7][8]. The most common approach is to use natural coconut and kenaf fibres [9,10].…”

Computational Investigations on Soundproof Applications of Foam-Formed Cellulose Materials

“…Further, empirical or multi-parameters models (the Delany–Bazley model, Biot model, Miki model, and Johnson–Champoux–Allard models, etc.) are utilized on a large scale for the prediction of the sound absorption coefficient considering the porosity and flow resistivity of the tested materials [39,40,41]. On the other hand, the inverse approach of material identification based on acoustical performances (absorption coefficient or flow resistance) has been tested and simulated using experimental data via the Bayesian approach [37,42,43].…”

Predicted Absorption Performance of Cylindrical and Rectangular Permeable Membrane Space Sound Absorbers Using the Three-Dimensional Boundary Element Method

“…To reduce and control the noise generated from various sources [1], and to create a quiet and comfortable sound environment, sound absorption is an important factor of building quality. Currently, natural fibers as absorptive materials are extensively investigated [2][3][4][5][6]. They are of recyclable and sustainable properties and show good absorption performance.…”