Normal Incidence of Sound Transmission Loss of a Double-Leaf Partition Inserted with a Microperforated Panel

Figure 7

STL improvement of DL-MPP system with different MPP parameters: (a) locations in the gap (𝑑_𝑜=1 mm, 𝜏=1.5%, and 𝐷=100 mm), (b) hole diameters (𝑙=0.1𝐷, 𝜏=1.5%, and 𝐷=100 mm), (c) perforation ratio (𝑙=0.1𝐷, 𝑑_𝑜=0.1 mm, and 𝐷=100 mm), and air gap (𝑙=0.1𝐷, 𝑑_𝑜=0.1 mm, and 𝜏=1.5%).

(a)

(b)

(c)

(d)