Design of Acoustic Panels in the Walls in Interior Spaces of Building by Imitating the Mechanism of Ferns

Noise pollution is one of the most important factors in architectural spaces that has a great impact on the comfort of residents. Today, man-made materials are used for improving the sound performance of buildings. For this purpose, it has been tried to find a way to control noise pollution with different materials such as glass wool, rock wool, foam types and acoustic tiles. Most of these materials are factors of environmental degradation and are not recyclable. The purpose of this study is to investigate the acoustic properties of plants and finding a suitable species to reduce noise pollution between two adjacent spaces, also imitating the ferns in order to improve the sound reduction of interior walls between residential units. This research is based on six stages. In the first stage, according to studies on the mechanism of plant texture, it is shown that plants have the ability to absorb sound. By using bionic methods, plants have been identified and their morphology has been done to determine the plant species that has this property. The second part of the research involves identifying the factors affecting sound absorption. At this stage, the possibility of adapting the acoustic principles to the plant texture has been measured. Then the effective parameters in its sound absorption have been investigated by computational and laboratory methods (using scales, calipers, AutoCAD software and Photoshop). Finally, the effect of the sound reduction on the wall is investigated by testing the panel via Cool Edit software and using the impedance tube. According to the results, the non-native fern "Nephrolepis exaltata" is an effective plant in sound absorption. Generally, non-native species of Iran have better sound absorption. According to the research results, all sound absorbers are like a soil layer and don’t have plant layer. The double-wall at frequencies of 250, 500, 1500, 1000 and 2000 Hz has the first priority and then the panel with the vegetable layer. The single-wall panel was tested by an impedance tube in the frequency range of 63 to 1600 Hz and the amount of sound reduction increased by increasing the frequency. The amount of sound reduction reached 18.29db at the frequency of 1600 Hz. This number is acceptable compared to other existing walls, for example, the amount of sound reduction of a wall with gypsum coated panels with mineral fibers with a thickness of 10 cm is 45 dB, while the designed panel with a thickness of 4 cm reduces the sound about 18 dB And by optimizing and increasing the thickness of the panel, the amount of sound reduction can be increased. To use the proposed walls in apartments and other spaces, panels with different characteristics as various thicknesses, different percentages of rice stem and poplar wood and different densities, hardness test on the wall, the aesthetics, the cleanliness of the panels, the late burning of the panels and the exact amount of sound reduction of each wall should be examined and tested.