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Ec pres.2 shah jahan mosque

Shah Jahan Mosque Acoustic Control

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Ec pres.2 shah jahan mosque

  1. 1. Shah Jahan Mosque Presented To: Sir Usman By: Asma Chaudary Hermain Anees Narmeen Khalid Mahnoor, Syed Bilal Ahmed Haseeb Saleem
  2. 2. LOCATION • The Shah Jahan Mosque is located in Thatta, Sindh province, Pakistan. It was built during the reign of Mughal emperor Shah Jahan.
  3. 3. HISTORY • The mosque was built in 1647, during the reign of Mughal King Shah Jahan, as a gift to the people of Sindh for their hospitality. It has been on the tentative UNESCO World Heritage list since 1993. • The mosque had undergone several renovations. More recently, the mosque was restored during the 1960s and 70s. • This Mosque is called with many names like Jama Masjid Thatta, Shahjahani Mosque and Badshahi Mosque Thatta.
  4. 4. PLAN
  5. 5. PLAN DETAILS • The mosque, a heavy brick structure of simple construction built upon a stone plinth, with heavy square pillars and massive walls, is centered around a courtyard 169' X 97'. The prayer chamber is of a similar size. Both are covered by large domes. On the north and south two aisled galleries open by means of arcades onto the courtyard. Ninety three domes cover the entire structure. • The mosque is spread over an area of 51,850 square feet. The main entrance of the mosque has a central domed chamber. The mosque has an open central courtyard of about 15,900 square feet.
  6. 6. • The abulation pond is located on a central courtyard located within the eastern portion of the mosque. • The main quality of the Mosque is that it has no minarets. Instead of the typical three domes, there is only one main dome in the prayer hall. Its 93 domes and 33 arches with varying sizes add to their architectural beauty. It is world's largest mosque having such number of domes. • More than 20000 people can pray in the mosque.
  7. 7. ARCHITECTURE • The mosque is built with red bricks with blue colored glaze tiles probably imported from the town of Haala, Sindh. • It is laid out in the usual quadrilateral arrangement with a large (52 x 30 meter) courtyard at its center. The arcades around the courtyard are covered with 93 domes of varying size. • Architectural styles: Islamic architecture, Mughal architecture.
  8. 8. • The two main chambers are entirely covered with blue gazed tiles. Their domes have been laid with a mosaic of radiating blue and white tiles. • Floral patterns, akin the Kashi work of Iran, decorate the spandrels of the main arches and elsewhere geometrical designs on square tiles are disposed in a series of panels.
  9. 9. • The mosque has also a ventilation system and during hot summer months one feels comfortable enough. • A little niche is built in on either side of the prayer niche (mihrab) in the qibla wall of the mosque and helps let in both light and fresh air into the chamber. • The slanted passageways are a peculiarity of architectural design in the mosque.
  10. 10. • It has been built keeping acoustics in mind. A person speaking inside one end of the dome can be heard at the other end when the speech exceeds 100 decibels. • Ninety three domes cover the entire structure, and are probably the cause of a remarkable echo, which enables the prayers in front of the Mihrab to be heard in any part of the building.
  11. 11. ACOUSTICS • Acoustics is a science that deals with the production, control, transmission, reception and effects of sound. • Acoustics is classically divided into sound and vibration. Sound refers to waveforms traveling through a fluid medium such as air, while vibration describes energy transmitted through denser materials such as wood, steel, drywall or anything besides a fluid. It is not heard as much as felt, due to its extremely low frequency, which is below the range of most human hearing.
  12. 12. DOMES • Domes are inherently echo chambers. • In a spherical geometry, rays are concentrated at focus point, with a uniform distribution, where propagation distances of sound paths are described as equal depend on the particular point the speaker takes. • The ideal dome with a steady state high sound concentration in a small area and uneven sound distribution across the entire audience area, and a deflected dome with a centre of sphere to an elliptical shape, which shows level variations across the audience area as smaller, thus providing a better coverage of the entire audience area – a better acoustic performance.
  13. 13. DOMES • In the deflected dome, an overall increase in speech intelligibility as well as an even distribution of sound level across the audience area can be seen. Furthermore, this shape supports even distribution of reflections across the audience area. • By bringing the back wall closer to the performer, useful reflections arriving at an early stage aid in raising the speech intelligibility across the audience area. • The structural deflection of original spherical geometry and resulting sound reflection in relation to curvature of the space enhances the acoustic performance of the space.
  14. 14. DOMES • Most modern domes are built from thin aluminium sections with ribs providing a supporting structure behind. The use of aluminium makes it easy to perforate the dome with thousands of tiny holes. This reduces the reflectivity of sound back to the audience (providing better acoustic characteristics) and allows air circulation through the projection surface for climate control. • The sound is carried by waves that travel around the circumference clinging to the walls. • When a visitor stands at one focus and whispers, the line of sound emanating from this focus reflects directly to the focus at the other end where the whispers may be heard.
  15. 15. DOMES • The adapting heights, varying position of centre points, varying dimensions and curvature of domes are the cause of echo produced throughout the mosque.
  16. 16. REVERBERATION • Reverberation is the persistence of sound after a sound is produced. A reverberation is created when a sound is reflected causing a large no. of reflections to build up and then decay as the sound is absorbed by the surfaces of objects in the space. Reverberation is frequency dependent. • Reverberation is a statistical process not relying on specific room shape and sound propagation paths. Reverberation decay sounds even and consistent to the human listener. The spaces are made less reverberant and more absorptive. The reflections contribute to sound buildup rather than to sound decay.
  17. 17. ECHOES • Echoes are reflections that can be heard distinctly and separately from the early reflected and reverberant sound. • Echoes are normally heard due to intense reflections arriving later after the direct sound signal has reached the listener. • Echoes are based on the sound level of reflections and their delay after the direct sound.
  18. 18. SLANTED WALLS • Slanted walls may eliminate some periodic modes of flutter echoes, but then may allow some more hidden ones. A hard plane wall act like an acoustic mirror so that reflections from the wall can be explained as coming from an image room behind the wall. Two walls meeting at a right angle will create three image rooms from where reflections appear to come from. • The flutter-echo can be explained as plane-wave reflections between two parallel surfaces in a cluster of image rooms.
  19. 19. SLANTED WALLS • It is useful to utilize angled walls as reducing the number of parallel surfaces in the room minimizes acoustic problems such as standing waves. Perfectly square rooms are the most difficult spaces to treat as they are prone to every acoustical issue. • The elimination of parallel wall surfaces also eliminates standing waves that cause certain frequencies to resonate as they echo back and forth between two walls or between the ceiling and floor.
  20. 20. SLANTED WALLS • By introducing angles to the walls, side-to-side or front-to-back sound waves cannot sustain themselves. These angled walls create opportunities to introduce large bass traps into the design and because the size gradually changes, they naturally deliver broadband absorption. • They can be used in the form of absorptive panels, diffusers or a combination of the two. • They can certainly minimize instances of flutter echo (higher frequencies).
  21. 21. SLANTED WALLS • Slanted passageways used in the mosque reduces the flutter echo and thus enhances the clarity of the sound being reflected.
  22. 22. GEOMETRICAL DESIGNS • The manner in which sound reflects depend upon the shape, texture and material of the space boundary. For a surface to be a good reflector of sound, its dimension should be at least one wavelength or larger than the lowest frequency being reflected. Reflected sound plays a critical role in maximizing loudness levels to the audience. • Sound can also reflect in a diffuse manner. The reflection is fragmented into many reflections having less intensity, which are scattered over a wide angle creating a uniform sound field. Three dimensional surfaces such as columns, ornamentation serve as diffusing elements and were used as an integral to the acoustics in 19th century spaces.
  23. 23. SUMMARY Following elements play an important role in the acoustics of the Shah Jahan Mosque. • Domes (supports even distribution of the sound and increases sound intelligibility) • Slanted walls (decreases the echo of the sound produced and increases the audibility of the sound) • Geometrical designs (increases the reflection of the direct sound and thus increases the audibility)