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What should the reverberation inside a masjid be?
Published in Christine Guillebaud, Catherine Lavandier, Worship Sound Spaces, 2019
The main concept behind this work lies in exposing the participant to different acoustical environments (each of which represents a predefined reverberation time), allowing him to experience these environments and finally judge the degree of their suitability or convenience for the recitation of the Holy Qur’an when leading spoken group prayers. For this purpose, a specially designed experiment and questionnaire were prepared. During the preparation, three considerations were borne in mind. Firstly, the number of the examined situations (or setups as they will be called later) should not be so great that a participant becomes exhausted and confused. Secondly, the Imam should draw on the memory of his performance during prayers in the real world (the masjid). Finally, these setups should ensure clear differences between reverberation times; thus the participant can easily recognize and distinguish these differences. The reverberation chamber of the Acoustic Research and Tests Unit ARTU in the FOED, KAU, was chosen as a basis for this experiment. The acoustical environment within the chamber was modified using two types of carpets: type-A and type-B, both carefully selected to satisfy the aforementioned considerations. For example, the two carpet types were chosen from real masjid carpets to satisfy both the second and third considerations. The face yarn of both is made of heat-stabilized polypropylene (PPHS). Type-A has knot density of 24 knots per square centimeter (KPSC), weight 2.75 kg/m2, pile height 10.5 mm, and overall thickness 12.57 mm. Type-B has knot density of 14 KPSC, weight 2.19 kg/m2, pile height 10.5 mm, and overall thickness 13.42 mm (Elkhateeb et al. 2016a).
Effects of weaving parameters on acoustic and thermal insulation properties of handmade carpets
Published in The Journal of The Textile Institute, 2023
Homa Maleki, Rouhollah Semnani Rahbar, Seyed Alireza Zolfaghari
In order to investigate the acoustic and thermal properties of handmade carpet, 16 samples with different values of knot density, and pile height were woven in an approximate dimension of 40 × 40 cm. knot density indicates the number of knots in a specific area. According to the INSO (Iranian National Standardization Organization) 1240 standard, knot density value was considered and reported as the number of knots per unit of 7 cm. Pile height refers to the length of the knot from the primary backing to the tip (Goswami, 2018). The two most common types of knot used in Iran to produce handmade carpet are the Persian knot (Pk) and the Turkey knot (Tk). Persian knot is an asymmetrical single knot in which the pile yarn forms only one loop around one of the two warps (Figure 1a). Turkey knot is a symmetrical type of double knot. In this type, the pile yarn forms a loop around two warps, and both ends of the pile come out between both warps (Figure 1b) (Goswami, 2018; Gupta et al., 2016). Handmade carpet samples in this study were woven by forming Persian or Turkey knots.