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Materials used | Methodology | Factors investigated considering acoustic absorption | Key findings | References |
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Coir fiber | Perforated plates backed by coir fibers | Position of perforation plate and air gap | Acoustic absorption was improved especially in low frequency spectrum | [15] |
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Jute felts | Perforated plates backed by jute felts | Position of perforation plate and thickness of backed fiber | Usage of perforation plates helped in improving the acoustic absorption in low frequency spectrum without increasing the jute belt’s thickness | [16] |
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Kenaf fiber | Hot pressing of the perforated plate | Fiber content | The highest acoustic absorption coefficient was recorded as 0.987 at 1521.02 Hz | [14] |
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Rice husks and sugarcane bagasse | Hot pressing of the perforated plate | Fiber content | The highest acoustic absorption coefficient was recorded as 0.58 at 4000 Hz | [17] |
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Coir | Hot pressing of the fiber | Density of the fiber layer | Acoustic absorption coefficient was observed to be 0.9 at 4000 Hz | [19] |
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Corn husk fiber | Molding of fibers | Alkaline treatment of fibers | Acoustic absorption coefficient was 100% in the frequency range between 1600 and 3250 Hz | [18] |
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Kenaf fiber, wood fiber, hemp fiber, and coconut fiber | Molding of fibers | Thickness of the fiber layer | All the natural fibers exhibited satisfactory acoustic absorption coefficient in midfrequency and high frequency spectrums | [13] |
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Recycled cotton fiber | 3D printed perforated plate made of VisiJet-SL (clear) backed by recycled cotton fibers | Perforation ratio | Significant improvement of acoustic absorption especially in low to midfrequency spectrum | [6] |
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Natural fiber composites | 3D printing of an acoustic panel | — | — | This review |
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