Browsing by Subject "Sound absorption coefficient"

Now showing 1 - 3 of 3

Open Access
Acoustical characterization of clay pots in Ottoman architecture through experimental and numerical analysis methods
(2022-07) Atay, Gülnihan
Employment of clay pots as building elements is a common practice especially in the medieval structures throughout Europe and Near East. Despite the fact that their acoustical employment in historic structures is well known and dates back to the 1st century BC as observed in Vitruvius' writings, their true contribution to the acoustics of Medieval Architecture remains to be a subject of discussion. They are also present in Ottoman Architecture including Süleymaniye Mosque designed by Sinan the Architect Laureate. Although these elements placed in the dome of Süleymaniye are often interpreted to be utilized as Helmholtz resonators, a scientific account regarding their sound-absorption performance is needed so as to understand whether they actually perform as cavity resonators. Therefore, the scientific investigation of their acoustical behaviour through analytical, experimental, and numerical analysis methods is necessitated. The objective of this study is to discuss the effects of the clay pots on the sound energy decay pattern of Süleymaniye Mosque. The study begins with an archival research phase covering the versatile employments of clay pots as building elements that are not limited to their acoustical utilization. The study then proceeds with the impedance tube measurements conducted with the reproduced sample of an actual-sized clay pot employed in the structure. The results are then verified with finite element modelling (FEM) simulations. Finally, sound absorption coefficients, obtained from the latter are transferred into the ray tracing simulations so as to understand the pots' effect on reverberation times (T30) in the edifice. In the conclusion part, sound absorption performance of clay pots and their possible contribution to the mosque acoustics are discussed. As a result of the study, the resonance frequency of the clay pots embedded into the central dome of Süleymaniye Mosque is found to be 50 Hz. Additionally, they are also proven to be effective at 500 Hz octave band. Consequently, the ray tracing simulations exhibit a 2 seconds decrease in T30 values at 500 Hz octave band. This also proves the improvement of reverberation time at this octave band range, which was measured after the final restorations of Süleymaniye Mosque with repaired pots.
Open Access
Biobased sound absorptive panel system design and development using fruit seeds
(2023-09) Tarman, Damla
In order to reduce the carbon footprint due to currently applied sound absorptive materials in the building construction field, alternative sustainable systems are investigated in this research. By re-using the waste fruit seeds that are abundant in the Central Anatolia region of Turkey, a composite panel system is developed to be applied in buildings as a fine finish surface, like a wall or ceiling panel. The raw material is composed of various fruit seeds, including cherry, watermelon, olive, etc. The tree resin is combined with wood fire ash as a natural adhesive. The efficacy of the adhesive property is the subject of biological adhesive research. Wood glue is utilized as an alternative to other adhesive materials; it is considered more efficient in material production due to its practicality and accessibility. The varied combinations of seeds, tree resin, and wood glue have been tested through impedance tube measurements, and sound absorption coefficient data are acquired. To test the efficiency of produced samples, one with the maximum sound absorption performance is tested in the design studio at Bilkent University based on the data obtained, which is a current acoustic problem due to very high reverberance. An acoustical model is generated replicating the problematic studio, and the panel system is tested through ray-tracing simulations. On the generated studio model, the panel system is applied to specific surfaces, and reverberation times for the current and adjusted state of the studio is compared. The results indicate that the panels out of seeds combined with proper adhesives have a potential to be applied as a sound absorptive decorative system in various architectural spaces.
Open Access
The effect of moisture content on sound absorption of expanded perlite plates
(Elsevier, 2005-03) Yilmazer, S.; Ozdeniz, M. B.
Expanded perlite is a porous, lightweight, fire resistant and moisture retaining material with sound and thermal insulation properties. In this research, acoustical behaviour of plates made of expanded perlite was studied experimentally. Since these plates are used for sound absorption, the acoustical parameter selected for this study is "sound absorption coefficient". Preliminary experiments indicated that moisture reduced the sound absorption coefficient on plates and there is not much significant difference between the dry and 50% humid conditions. However, there is a significant difference in acoustical properties for the 50-95% humid conditions. Thus, this interval was studied in detail. A number of expanded perlite plates having different mixtures were prepared and tested. It was observed that, coating the expanded perlite particles with sodium silicate increased the moisture resistance. and the addition of mineral fibres into the mixtures increased the strength and sound absorption coefficient of the plates.