The acoustical design of the new lecture auditorium, Faculty of Law, Ain Shams University

This work represents the main acoustical design phases for the new lecture auditorium in the Faculty of Law, Ain Shams University, Cairo/Egypt. The work also discusses some of the architectural details that were used and have a direct effect on the acoustical environment inside the auditorium. The work compares finally among field measurements (that were recorded after the construction in the unoccupied auditorium), the values expected during the acoustic design phase (utilizing ODEON ver. 4.2, assuming the occupied case), and the optimum values for speech intelligibility indicators that were considered in this work (T20, D50, STI, LAeq, and the background noise). Field measurements that were recorded utilizing MLSSA system showed that the finishing materials used successfully fulfilled a good level of speech intelligibility in the auditorium. The estimated reverberation time T20-EOC for the occupied room (based on the measured unoccupied T20-M) was close to the optimum especially in mid and high frequency bands. The measured D50 (unoccupied) was found to be within its acceptable range. The measured STI value (unoccupied) was ‘‘Fair, 0.49’’. The measurements of LAeq indicated the uniformity of the acoustical field in the room. The noticed problem was a relatively high background noise (NC-40) due to the utilization of natural ventilation which directly contradicts the principles of room isolation.