Optimizing acoustic conditions for two lecture rooms in Faculty of Agriculture, Cairo University

AbstractThis paper analyses the acoustic conditions inside two lecture rooms in faculty of agriculture, Cairo University, based on field measurements and simulation technique. Ambient noise and reverberation time were measured in the unoccupied rooms. The measurement results were utilized for validating the results of CATT software that was used to estimate occupied reverberation time, STI and C50. These parameters were analysed in comparison with rooms’ properties, optimal reverberation time and maximum acceptable noise for learning spaces. The results demonstrated that acoustic design of the first room is far from the recommended values, whereas the second room includes many defects. For optimizing the rooms’ performance, acoustic treatments were proposed and explored. Results clarified that reducing the excessive reverberation to the optimal value, either by increasing room absorption or decreasing room volume, significantly optimizes speech intelligibility. The results also clarified that reforming the ceiling eliminated the shadow and increased the early reflections

Analyzing the Newest Interchange Connection at Cairo Metro Network Pertaining to Passenger Flow

The French standard governing occupanckes dedicated for gatherings of individuals and institutions receiving the public, including railway stations and tunnels was used in the design of Cairo’s transit network, which consists of three lines connected through three existing interchange connections and one that is currently under construction. There is a lack of studies quantifying passenger evacuation in relation to Cairo transit, especially with regard to the interchange connections. This study assessed the viability of the evacuation methods applied to the design of interchange connections in Egypt. The emergency evacuation procedures for the future interchange connection layout between Lines 1 and 3 were assessed using the French standard and NFPA 130 Standard for Fixed Guideway Transit and Passenger Rail Systems analytical methods. The analysis accounts for the traffic forecast as presented in the Egyptian company for operation and maintenance report for Line 1 and the feasibility study of Line 3. The results demonstrated that the connection was compliant with the French standard, but it did not fully meet NFPA requirements. It was concluded that there is still room for enhancement and for gaps to be considered. Recommendations include undertaking investigations into passenger characteristics and behavior in the context of passenger flow in emergency situations using approaches such as virtual research and field surveys, and simulation techniques

The Optimal Reverberation for Masjids: A Subjective Assessment for Worshippers’ Demands

This study investigates the optimal reverberation time in masjids (mosques) from worshippers' viewpoint for the two modes of performance: recitation and sermon/speech. It also examines the effect of both age and gender on worshippers' preferences. To this end, specially convolved five audio clips (five acoustic setups) for each mode were created and uploaded to Google Drive. More than 300, Arabic-speaking participants, males, and females of different ages, listened to these clips. The participants judged the quality (Q, or appropriateness) of these audio clips for listening either to the recitation (QR) or speech (QS) on a unipolar discrete five-grade scale via a questionnaire that was created on Google Forms. Results indicated that both QR and QS are functions of gender and age. Overall, younger worshippers preferred higher reverberation and vice versa, while gender significantly affected the perception of the desirable reverberation for both recitation and speech. Females tended to the shorter reverberant environment (1.38 s for recitation mode, 0.75 s for speech mode, in the mid-frequency range) than males who preferred longer reverberation for recitation in particular (1.77 s)

Acoustic improvement on two lecture auditoria: Simulation and experiment

Based on the commonly used indicators for speech intelligibility, this work acoustically evaluates the two largest auditoria in the Faculty of Engineering, Helwan University, Cairo, Egypt, using experimental and digital simulation techniques. Design treatments were also suggested to improve the acoustic performance of the auditoria, where the impact of these treatments was checked using the simulation as well. The models that were analysed using the CATT software were first validated utilizing the results of the field work in the unoccupied rooms. The results showed that the acoustic quality of the two auditoria are far from the optimal conditions due to their improper acoustic characteristics and the high noise levels as well. The results of improvement proposals showed that altering the ceiling shape and adding efficient absorptive materials to the rear surfaces successfully reduced the excessive reverberation time to the optimal values, increased the early reflections and eliminated the shadow zones. In addition, decreasing the noise levels by 20 dB due to improving the window insulation noticeably improved the speech intelligibility at all receivers

Acoustic improvement on two lecture auditoria: Simulation and experiment

Based on the commonly used indicators for speech intelligibility, this work acoustically evaluates the two largest auditoria in the Faculty of Engineering, Helwan University, Cairo, Egypt, using experimental and digital simulation techniques. Design treatments were also suggested to improve the acoustic performance of the auditoria, where the impact of these treatments was checked using the simulation as well. The models that were analysed using the CATT software were first validated utilizing the results of the field work in the unoccupied rooms. The results showed that the acoustic quality of the two auditoria are far from the optimal conditions due to their improper acoustic characteristics and the high noise levels as well. The results of improvement proposals showed that altering the ceiling shape and adding efficient absorptive materials to the rear surfaces successfully reduced the excessive reverberation time to the optimal values, increased the early reflections and eliminated the shadow zones. In addition, decreasing the noise levels by 20 dB due to improving the window insulation noticeably improved the speech intelligibility at all receivers