tailieunhanh - Building systems for_interior designers phần 10

Hình 51-1 vật liệu khổng lồ. CMUs, đặc biệt là khối than, hơi xốp, trừ khi sơn hoặc đóng dấu. Nếu niêm phong, CMUs có thể phản ánh tất cả các tần số tốt. Các hình thức khác của nề khác nhau, nhưng tương tự như gạch, bê tông, và CMUs. Stone, bao gồm vật liệu tái tạo như terrazzo, có thể được sử dụng cho lớn, tường chịu lực, đá phải đối mặt với veneer, hoặc mở. | Acoustic Design 407 Double brick wall both reflects and absorbs sound Concrete-filled concrete masonry unit reflects and absorbs sound Massive materials keep sound from traveling from one side to the other. Reflective materials bounce sound back into the space of its origin. Figure 51-1 Massive materials. CMUs especially cinder blocks are slightly porous unless painted or sealed. If sealed CMUs can reflect all frequencies well. Other forms of masonry vary but are similar to brick concrete and CMUs. Stone including reconstituted materials such as terrazzo can be used for massive load-bearing walls stone veneer facing or paving. Thick well-sealed stone walls attenuate sound very well. Marble is among the most acoustically reflective materials. Some stone is naturally porous and therefore less reflective. Plywood has a modest amount of mass and is relatively ineffective for attenuating sound. Thin plywood furred out from a solid wall is a good absorber of low frequencies. Plywood is quite reflective at high frequencies. Figure 51-2 Reflective materials. Glass is massive but thin so its ability to attenuate sound is marginal. Well-separated double-glazing offers superior sound attenuation as do some types of laminated glass. Laminated glass consists of two or more sheets of glass with interlayers that provide damping as the glass sandwich is flexed. Some types of laminated glass have substantially better attenuation than equal thicknesses of glass alone. Glass reflects higher frequencies almost completely. Because glass resonates it will absorb good amounts of low frequencies. When designing interior glazing glass lights with ỉ laminated glass set in resilient framing have more mass and offer better damping than plain glass in rigid frames. REFLECTIVE MATERIALS o A smooth dense wall of painted concrete or plaster absorbs less than 5 percent of the sound striking it therefore making an almost perfect sound reflector Fig. 51-2 . Applying a skim coat of plaster makes very