Quiet environment： Acoustics of vertical green wall systems of the Islamic urban form

The development of sustainability has made the application of green concepts to cityscapes and urban design mandatory and has popularized the installation of vegetation on external street walls. Introducing greenery on external building elements is beneficial to the environment, reducing the heat impact experienced in ＂urban heat islands＂ and enhancing an area＇s visual effect. The popularity of such green systems has necessitated the assessment of their acoustic characteristics and their impact on long-distance noise propagation. These effects become important in hot climates, where the topology of the dense urban texture gives building walls larger areas than exposed streets, thereby amplifying the effects of the former＇s acoustic characteristics on noise levels. Considering the resultant sound level at a particular location between buildings as the contribution of several remote sources, a simplified computer model based on energy exchange is developed in this study. Owing to the complexity of the urban landscape, buildings are assumed to be an array of rectangular blocks. The computer model is used to investigate the effects of the installation of street vertical ve^letation on long-distance noise propagation, as well as those of the geometric parameters of the dense Islamic urban texture on the resultant noise levels.

Sound preferences of the dense urban environment： Soundscape of Cairo

A questionnaire study was conducted to investigate the soundscape preferences of the sonic environment in Cairo. Participants, who were Cairo residents, were questioned about their appraisal of fami（iar urban soundscapes in a dose- and open-ended format questionnaire. Psycholinguistic data analysis of verbal descriptions expressed by respondents was conducted to identify the re（evance of semantic categories of environmental sounds and quantitative soundscape aspects for the urban sonic environment of Cairo. Resu（ts confirmed a direct retevance of the linguistic semantic auditory judgment and of the outputs of the quantitative dose-ended questions. Cairenes were also found to express their sonic environment （inguisti- cal（y based on physical properties rather than semantic features and values. Analyzing the relative annoyance increase （RAI） of the dose-ended part, overall positive RAI va（ues for all sound categories reveal how sensitive to noise Cairo residents are. Results further showed that at an RAI value of approximately 27%, sound category perception transforms from positive to negative.

A parametric investigation of the acoustical performance of contemporary mosques

Acoustics is an important factor in mosque prayer halls that had not been given extensive concern during the architectural design stages. Eventually, the importance of speech intelligibility became more important, given the integration of other activities into the prayer halls, such as the holy Quran recitation, speeches, and lectures. Early attempts have been made to control the propagation of sound and to maintain good acoustic quality within the prayer spaces. Architects during the conceptual design stage had barely paid attention to the design issues that affect the acoustic environment inside the prayer zones, which is either due to lack of time during the project development or, in most cases, a lack of simple design guidelines to overcome any drastic acoustical defects arising from the incorrect design, shape, or material selection. The basic guidelines for designers to select the appropriate shape, geometry, size, and finishing materials are an essential design tool. This work examines the three common design topologies of mosques, which differ in size, shape, and finishing materials. In this study, a geometric and material parametric analysis was conducted based on the shape, surface area, volume, and finishing materials of each of the three designs. For the geometric acoustics, a computer model employing the ray tracing theory was employed to investigate the three configurations. Different acoustic treatments were tested relative to the geometric disposition of each design. Finally, basic recommendations and design guidelines were presented.

Acoustic of monolithic dome structures

Monolithic dome structures were built in the 1970s in Europe and America. These dome structures share common benefits of being cost-efficient, earth-friendly, extremely durable, and easily maintained. Monolithic shells are easily constructed and are extremely cost- effective. Monolithic domes respond efficiently to any climate, even to extremely cold or hot temperatures. In terms of utility savings, monolithic domes can cut electricity consumption by up to one-third, thereby saving 60-70% of total enersy costs. Moreover, monolithic structures provide the hishest survivability rates from destructions. The interior of monolithic domes have perfect, concave shapes to ensure that sound travels throush the dome and perfectly collected at different vocal points. These dome structures are utilized for domestic use because the scale allows the focal points to be positioned across daily life activities, thereby affecting the sonic comfort of the internal space. This study examines the various acoustic treatments and parametric configurations of monolithic dome sizes. A geometric relationship of acoustic treatment and dome radius is established to provide architects guidelines on the correct selection of absorption needed to maintain the acoustic comfort of these special spaces.