Biology, Medicine, & Natural Product Chemistry ISSN 2089-6514 (paper) Volume 14, Number 2, October 2025 | Pages: 615-619 | DOI: 10.14421/biomedich.2025.142.615-619 ISSN 2540-9328 (online) The Acoustic Material Constructed by the Fiber of Eichhornia crassipes and Banana Peel as a Sound Pollutant-reducing Solution Regita Dimar Asyurra1, Avivah Afra Amatullah1, Annisa Zaskia Puteri1, Mayshilla Anatayya Putri Zevly1, Angga Puja Asiandu2, Widya Sari3,* 1Islamic Harapan Mulia Senior High School, Palembang 30135, Indonesia. 2Faculty of Biology, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia. 3Department of Physics, Faculty of Mathematics and Natural Science, Universitas Gadjah Mada 55281, Indonesia. Corresponding author* widya4895sari@mail.ugm.ac.id Manuscript received: 20 March, 2025. Revision accepted: 13 July, 2025. Published: 01 October, 2025. Abstract This study aims to evaluate and compare the effect of the composition of water hyacinth (Eichhornia crassipes) with a banana peel on the absorption coefficient value as a composite material for absorbing sound waves. The cellulose within the water hyacinth and banana peel lead to reduced overload sound waves. This study used an experimental method providing banana peel crushed into powder, water hyacinth fiber, and resin (as a catalyst). All samples were prepared with dimensions of 13.5 cm × 25 cm × 0.8 cm. A frequency generator application was used as the sound source (125, 250, 500, 1000, and 2000 Hz), while a sound meter application measured sound intensity (dB). The results indicated that the outer surface of sample D had a superior absorption coefficient, measuring 0.51 at 250 Hz and 0.45 at 2000 Hz. Meanwhile, the inner surface of sample D recorded absorption coefficients of 0.46 at 250 Hz and 0.45 at 2000 Hz. Variations in absorption values were attributed to destructive interference and saturation. Sample D contained more water hyacinth (approximately 30%) than banana peel powder. This suggests that water hyacinth and banana peel powder are viable natural fiber alternatives for sound wave absorption. Keywords: absorption coefficient; banana peel; water hyacinth; sound; cellulose. INTRODUCTION Noise pollution can disrupt human activities and affect mental health due to excessive noise. Sound can also trigger psychological disorders in terms of health, such as sleep disorders, hearing disorders, hormonal disorders, increasing the incidence of diabetes, and even heart disease (Safira & Safira, 2017). According to the regulation of the Minister of Health of the Republic of Indonesia No. 718/MENKES/PER/XI/1987, noise is an unwanted sound that causes discomfort to the listener (Kementerian Kesehatan RI, 1987). WHO noted that Europeans have been exposed to excessive noise from road noise as many as 1 in 5 or around 100 million (WHO, 2024). The negative impact of excessive noise is explained by (Wahyudi, 2018) that people in the Cement Industry experience dizziness, headaches, and hearing loss due to a threshold value of 80-85 dB that exceeds the threshold value set for the industry, which is 70 dB. Threshold Limit Value is the value of disturbance that a person can still accept without causing temporary or permanent hearing loss (below 90 dB). If an individual receives sound more than 90 dB for a long time, it will cause physical disorders in the ear organ (Eryani et al., 2017). Regarding the limit value, each country has different regulations. Japan for residential areas has two limit value determinations, where 45 dB is for the daytime limit and 40 dB at night (Khan & Burdzik, 2023). Unlike Japan, the discovery of the limit value in Europe has three time periods. The limit value in residential areas is around 55 dB during the day. The threshold value in the afternoon is around 50 dB. While at night, the limit value is 45 dB (Khan & Burdzik, 2023). Currently, several acoustic studies develop sound wave-absorbing materials based on natural fibers. Fibers from hemp, coconut, and abaca have the potency to control noise (Rifaida Eriningsih et al., 2014). Sound- absorbing composites will be characterized by the type of fiber, the physical properties of the fiber, and the morphology. In addition, the absorption coefficient α, ranging from 0 to 1, also determines the absorbed quantity. This value ranges from 0 to 1. If the coefficient value is 1, it depicts that the sound waves are perfectly absorbed 100 percent by the material (Astatika & Dwijaya, 2016). Sound-absorbing materials are indicated by the presence of pores to capture sound waves (Putra & Nazhar, 2020). Water hyacinth and banana peels have https://doi.org/10.14421/biomedich.2025.142.615-619 616 Biology, Medicine, & Natural Product Chemistry 14 (2), 2025: 615-619 pores that can become acoustic materials when processed. Water hyacinth, Eichhornia crassipes, is a watery plant with massively higher productivity that can disturb the aquatic environment and ecosystem balance. It is not a primary commodity for the community, but it scientifically has natural fiber with a crude protein content of 9.79%, crude fiber of 22.41%, crude fat of 2.82%, ash of 13.32%, and water content of 7.76% (Sihite et al., 2014). Water hyacinth also has a lignin content of 17% (Kusumawati & Haryadi, 2021). On the other hand, banana fruit is widely used by the community, is accessible, and has a low price. The banana peel takes two years to degrade so it will accumulate being waste. It is discovered by fiber content of 17.12%, protein of 9.55%, and crude fat of 4.94% (Fauzana et al., 2012). Banana peel also has a cellulose content of 14.04% and a hemicellulose content of 37.52% (Nasrun et al., 2014). Banana peels and water hyacinth are fabricated as an acoustic material. Therefore, this study will assess the effect of water hyacinth fiber and banana peel composites on the absorption coefficient value of both the outer surface of the material and the inner surface of the material. MATERIALS AND METHODS Study area This study stage includes preparation, fabrication, and testing. The testing limits the measurement of the absorption coefficient to indicate the comparison of materials’ capacity. Figure 1. Measurement Design of Acoustic Material. Before measurement, the upper of design should be closed by the material Procedures The ingredients contain water hyacinth fiber, banana peel fiber, and polyester resin. The fibers of both materials are exposed to the sunlight. After drying, the water hyacinth fibers are separated and soaked in Sodium Hydroxide (NaOH) and dried again. Meanwhile, the dried banana peel is mashed into powder. Then, all ingredients are divided based on the calculation of variation. There are four variations in the fabrication of acoustic materials, namely (a) sample variation A consists of 60% resin, 40% banana peel, and 0% water hyacinth; (b) sample variation B consists of 60% resin, 30% banana peel, and 10% water hyacinth; (c) sample variation C consists of 60% resin, 20% banana peel, and 20% water hyacinth; and (d) sample variation D consists of 60% resin, 10% banana peel, and 30% water hyacinth. Water hyacinth fiber and banana peel are combined according to the calculation per variation using a mixture of resin and catalyst in a mold. All samples were set in sizes of 13.5 cm x 25 cm x 0.8 cm. Data analysis Acoustic material samples will be evaluated on the outside and inside of the material with frequencies of 250, 500, 1000, and 2000 Hz. For the assessment, A smartphone should provide the Frequency Generator application as a sound source generator and the Sound Meter application as a sound intensity meter (Figure 1). The material will be assessed for the absorption coefficient (α). It indicates that the total sound energy can be absorbed by the material. Repetition of calculation is carried out as many as four times. The absorption coefficient value of the material will be obtained from the intensity value equation as follows. 𝐼𝑡 = 𝐼𝑖𝑒 −∝𝑥 Where: 𝐼𝑖 : The initial intensity of sound wave (W/m2) 𝐼𝑡 : The transmitted intensity of sound wave (W/m2) 𝑥 : the thickness of material (m) 𝑎 : the absorption coefficient of material (𝑚−1) RESULTS AND DISCUSSION Table 1 and Table 2 are the results of sound intensity and absorption coefficient, respectively. There are differences in the initial intensity value and the transmitted intensity when given a sound source directed at acoustic material with different frequencies. The higher the frequency emitted, the more the absorption coefficient value of each sample tends to increase (Table 2). Sample D has the highest coefficient value of 0.51 at a frequency of 250 Hz and 0.45 at a frequency of 2000 Hz compared to other samples consisting of 60% resin, 10% banana peel, and 30% water hyacinth. The higher the percentage of water hyacinth around 40%, the higher the absorption coefficient value of around 0.343 (Harfi et al., 2023). Asyurra et al. – The Acoustic Material Constructed by the Fiber of … 617 Table 1. The comparison between the initial intensity and the transmitted intensity for outside surface material. Frequency (Hz) Material 𝐼𝑜 (dB) I (dB) 𝐼𝑜 (dB) I (dB) 𝐼𝑜 (dB) I (dB) 𝐼𝑜 (dB) I (dB) A1 A2 A3 A4 125 63 34 63 27 63 35 63 35 250 71 52 71 46 71 51 71 53 500 87 74 87 71 87 71 87 71 1000 88 73 88 67 88 65 88 68 2000 88 60 88 73 88 73 88 73 B1 B2 B3 B4 125 63 41 63 38 63 40 63 36 250 71 54 71 54 71 55 71 52 500 87 73 87 69 87 69 87 68 1000 88 68 88 64 88 66 88 69 2000 88 66 88 64 88 65 88 64 C1 C2 C3 C4 125 63 34 63 32 63 27 63 32 250 71 50 71 49 71 51 71 52 500 87 67 87 73 87 70 87 71 1000 88 64 88 66 88 72 88 75 2000 88 71 88 70 88 69 88 67 D1 D2 D3 D4 125 63 33 63 28 63 32 63 33 250 71 49 71 45 71 49 71 49 500 87 62 87 66 87 66 87 68 1000 88 67 88 65 88 71 88 68 2000 88 60 88 62 88 64 88 63 Table 2. The absorption coefficient for outside surface material. Tables 3 and Table 4 explain the results of intensity and the absorption coefficient from the inner surface, respectively. The higher the frequency applied to the same sample, the absorption coefficient value tends to increase. The instability of the absorption coefficient is caused by particles in the acoustic material experiencing saturation and destructive interference (Sinaga et al., 2012). In some frequencies, fluctuations have occurred due to interference from noisy activities in the surrounding environment during the data collection process. The sound meter is also sensitive to the surrounding sound and causes the intensity of the sound read to fluctuate. The highest absorption coefficient with a value of 0.50 is measured in sample D, which consists of 30% water hyacinth, 10% banana peel, and 60% resin. Sample D can be an alternative because its absorption value reaches 0.50 and exceeds the ISO 11654 standard, a minimum absorption coefficient value of 0.15 (Said L et al., 2020). Table 3. The comparison between the initial intensity and the transmitted intensity for inside surface material. Frequency (Hz) Material 𝐼𝑜 (dB) I (dB) 𝐼𝑜 (dB) I (dB) 𝐼𝑜 (dB) I (dB) 𝐼𝑜 (dB) I (dB) A1 A2 A3 A4 125 63 43 63 36 63 34 63 28 250 71 54 71 52 71 51 71 49 500 87 65 87 61 87 68 87 71 1000 88 73 88 71 88 75 88 75 2000 88 62 88 64 88 68 88 63 B1 B2 B3 B4 125 63 34 63 37 63 35 63 35 250 71 48 71 51 71 52 71 53 500 87 65 87 67 87 65 87 70 1000 88 68 88 70 88 69 88 68 618 Biology, Medicine, & Natural Product Chemistry 14 (2), 2025: 615-619 Frequency (Hz) Material 𝐼𝑜 (dB) I (dB) 𝐼𝑜 (dB) I (dB) 𝐼𝑜 (dB) I (dB) 𝐼𝑜 (dB) I (dB) 2000 88 63 88 59 88 61 88 64 C1 C2 C3 C4 125 63 28 63 32 63 27 63 31 250 71 49 71 53 71 51 71 49 500 87 72 87 69 87 70 87 66 1000 88 73 88 73 88 73 88 73 2000 88 65 88 62 88 64 88 57 D1 D2 D3 D4 125 63 31 63 32 63 36 63 32 250 71 51 71 50 71 48 71 50 500 87 62 87 52 87 64 87 64 1000 88 72 88 74 88 74 88 74 2000 88 63 88 62 88 60 88 63 Table 4. The absorption coefficient for inside surface material. CONCLUSIONS Natural fibers derived from banana peels and water hyacinth fibers have the potency to absorb sound waves. The absorption coefficient is one of the requirements that indicate the ability of a material to absorb sound waves. The absorption coefficient ranges from 0 to 1. The closer the absorption coefficient value is to 1, the more sound waves are absorbed, resulting in lower sound intensity. From the sample variations, sample D has a higher absorption coefficient compared to other samples. The absorption coefficient for the outer surface of sample D is 0.51 at a frequency of 250 Hz and 0.45 at a frequency of 2000 Hz. Besides, the absorption coefficient for the inside of sample D is 0.46 at a frequency of 250 Hz and 0.45 Hz at a frequency of 2000 Hz. Destructive interference and saturation are some of the causes of instability in absorption values. Thus, sample D is the best sound wave absorbing material compared to other variations with a composition of water hyacinth that is more than a banana peel. Acknowledgements: We sincerely appreciate everyone who has supported us throughout this process, from the initial preparation to presenting our results and ultimately writing this manuscript. In particular, we extend our gratitude to the Harapan Mulia Palembang Foundation and Mr. Trisno for their financial and moral support. We are also grateful to Ms. Delima for her guidance and assistance during our time in Thailand. A special thanks to our dedicated teammate, Essik, for always supporting us during the experiments. Lastly, we express our heartfelt appreciation to our parents for their unwavering understanding and support. Authors’ Contributions: Regita D. Asyurra, Avivah A. Amatullah, Annisa Z. Puteri, and Mayshilla A. Putri Zevly conducted the experiment, collected data, and wrote the manuscript. 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