CAHRISMA

The CAHRISMA project (Conservation of the Acoustical Heritage by the Revival and Identification of the Sinan’s Mosques’ Acoustics) is a three-year project financed by the EU. The purpose of the project is to study the acoustics of old Byzantine churches and mosques built by the ancient Turkish architect Sinan. A new measuring program was developed for the acoustic measurements in the rooms. The program uses a sweep technique previously developed and used at DTU. In short, an omnidirectional loudspeaker emits a sinusoidal sweep signal in the room, and the response of the room is simultaneously recorded with a two-channel microphone. The sweep signal is emitted and recorded through an audio card (Roland Audio Canvas UA-100) connected to a PC, using a commercial multitrack recording software (N-Track studio), and the recorded sweep is stored on the hard disk of the PC. The sweep response is then deconvolved with the inverted sweep signal, the result being the impulse response of the room. From the impulse response the different objective room acoustic parameters are calculated in the program. The average reverberation times measured in six rooms are listed in the table above. Acoustic models of three churches (Hagia Sophia, Saint Irene and Sergius & Bacchus) and three mosques (Süleymaniye, Selimiye and Sokullu) have been developed in ODEON. These rooms have a high geometrical complexity with spherical and cylindrical shapes dominating the rooms, especially large domes and numerous columns.