The Acoustic Characterization of Worship Ambiance and Speech Intelligibility in Wooden Hypostyle Structures: The Case of the Aslanhane Mosque

Abstract

The challenge in the acoustics design of the traditional mosque is twofold. First, the interior atmosphere of the space should create a sacred feeling on the users' holistic and phenomenological spatial perception, which is generally recognized as a direct effect of increased reverberation time (T30) and low clarity (C80). Second, speech should be adequately intelligible, which requires a low T30 and high speech clarity, contradicting the initial concern of the sacred atmosphere. We hypothesize that in Islamic architecture, wooden hypostyle mosques may comply better with the reverberation time requirements of speech intelligibility, while maintaining the sacred feeling, due to their comparatively absorptive surface finishing materials and structural elements. The Aslanhane Mosque is a unique sacred structure within its era of construction, well-known with its wooden columns and ceiling. It is an important case for room acoustics analysis of such holy spaces. This study aimed to analyze the room acoustic measurement results of the Aslanhane Mosque, evaluating the intelligibility of speech and interpreting the sacred feeling created by reverberance, envelopment, and spaciousness, which are all crucial in such holy structures. It is revealed that although the Aslanhane Mosque's subjective rating for speech intelligibility is "good," the overall low volume of the mosque and the lack of surface reflections decrease the sacred sensation. Additionally, the intelligibility of speech is vulnerable to obstacles within the line of sight, such as load-bearing columns. Lastly, it was observed that the increase in T30 at low frequencies improved the sacred sensation, envelopment, and spaciousness, without any profound negative impact on the intelligibility of speech.