2nd Track : Rethinking the Mosque Architecture of the Future
Role/Contribution
Author
Research paper Title
Criteria and Methods for Acoustical Evaluation of a Mosque: A Case Study of the Kobe Mosque, Japan
Personal Biography
Prof. Dr. S. M. Najmul Imam is a Professor in the Department of Architecture, Bangladesh University of Engineering and Technology (BUET), Dhaka, Bangladesh. He has received his B. Arch and M. Arch degree from BUET, while acquired his PhD degree on Building Acoustics from Kyoto University, Japan. After graduation in 1989, Dr. Imam worked as a practicing architect for five years and designed several buildings in Bangladesh and abroad. He joined as a Lecturer in the Department of Architecture, BUET in 1994 and continuing till date in different positions. His major field of teaching, research and practice is environment and energy in architecture, including acoustics, thermal comfort, lighting, sustainability and green building practice; keeping a special interest and expertise in Building Acoustics. Notably, he had been acoustical consultant of Bangladesh National Assembly Building. He has acquired skills and practical experiences on computer based parametric design methods applying acoustical simulation techniques, which is currently state-of-the-art in the field of acoustical design and assessment. He has practical experiences of designing numerous public and private projects highlighting building acoustics and other environmental issues. Prof. Imam takes building acoustics related courses both in undergraduate and postgraduate levels; supervises postgraduate research, contributes in conferences, workshops and journals. He is a Fellow in the Institute of Architects Bangladesh (IAB). He has contributed as a Member of Editorial Subcommittee and also as the Author of the Chapter 'Building Acoustics' in Bangladesh National Building Code (BNBC) 2020. Along with various academic and administrative activities, Dr. Imam has served as the Coordinator of Environment and Energy Division. He is a Member of the Executive Committee in the Green Architecture Cell (GrACe) and In-Charge of Acoustical Lab, Department of Architecture, BUET.
Paper Abstract
A satisfactory acoustical environment is essential in a mosque for performing key activities such as congregational prayers, theological teachings, and discussions. Mosques primarily involve two types of sounds: speech and melodious bare-voice recitation from the Holy Quran. Speech requires more intelligibility than liveliness, while melodious recitation demands more liveliness than intelligibility. Considering these unique and inverse acoustical requirements, this study proposes criteria and methods for the acoustical evaluation of mosques. By integrating complementary subjective and objective methods, the study holistically evaluates the auditory experience of users alongside technical parameters. These include questionnaire surveys, physical measurements, and parametric analysis of Percentage Syllable Articulation (PSA), Impulse Response, Reverberation Time (RT), Background Noise Level, diffusion of Sound Pressure Level (SPL), Speech Transmission Index (STI), Rapid Speech Transmission Index (RASTI), and computational simulations.
To demonstrate these evaluation criteria and methods, a case study was conducted on the Kobe Mosque in Japan, serving the Muslim community since 1935. Architecturally, the mosque resembles a typical North Indian style with its dome, minarets, and other features. The study focused on the main prayer hall with a mezzanine floor, having a volume of 385 m3. The questionnaire survey yielded an average rating of 1.12 on a scale from +2 to -2, indicating acoustical performance between ‘Good’ and ‘Very good’. Impulse Response showed an average RT ranging from 1.67 s to 0.71 s for a range from 125 Hz to 8 kHz. Noise Levels (Leq) ranged from 39.9 dBA to 52.4 dBA under various conditions. The average STI of 0.64 and RASTI of 0.62 rated the speech intelligibility and overall acoustical performance as ‘Good’ on a quasi-subjective scale. Computational parametric analysis and simulations confirmed these results. The proposed criteria and methods are expected to assist future research and practice, particularly in the Post Occupancy Evaluation (POE) of mosque acoustics.
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