Sound absorption of dried brown, red, green algae

Abstract

Algae are photosynthesizing organisms found in both freshwater and marine habitats. Studies on algae applications emerged recently due to its fast-growing biomass. Algae are widely used for biofuel, wastewater treatment, and bioplastic production applications. This paper investigates dried algae for sound absorption applications. The sound absorption was measured using the impedance tube, transfer function method. Three different types of algae: red, brown, and green, and their natural mixtures, were used in this study. The algae samples were changed in density of 50; 75; 100; 125; 150 kg/m3 to find optimal sound absorption. The results showed that average sound absorption coefficient in frequency range of 160 to 5000 Hz (αavg.) varied from 0.45 to 0.68. The highest (αavg.) was found when measuring a sample of mixture of brown and red algae (density 100 kg/m3). The frequency of the first peak of sound absorption depends on the density. The first peak frequency (500 Hz to 1250 Hz) depends on the density of algae samples. The highest peak of the sound absorption coefficient was found at 1000 Hz reached 0.98 when measuring samples of green and red algae mixture (density 75 kg/m3). The aim of this paper is to gain a significant knowledge of the sound absorption properties of macro algae and propose green materials for sound absorption applications.