**Acknowledgements**

**A: Basis weight**

**Table 5.** Correlation between variables and responses.

samples containing bicomponent fibers.

**4.4. Correlations**

54 Engineered Fabrics

**5. Conclusion**

[21, 30].

**B: Fiber type Air permeability Mean pore** 

A: Basis weight 1.000 0.000 −0.927 −0.921 0.911 B: Fiber type 0.000 1.000 −0.133 0.313 0.284 Air permeability −0.927 −0.133 1.000 0.882 −0.869 Mean pore diameter −0.921 0.313 0.882 1.000 −0.741 Sound absorption 0.911 0.284 −0.869 −0.741 1.000

The correlations between the independent parameters, basis weight (A) and fiber type (B), and the dependent parameters, air permeability (C), mean pore diameter (D), and sound absorption (E), has been examined and the results for the data obtained in the study are shown in **Table 5**. The statistical results have showed that air permeability, mean pore diameter, and sound absorption have significant correlation. Correlations between each of variables proved

In this research, acoustic insulation behavior of SMS type composite nonwovens has been investigated. The results show that sound absorption has been affected by fiber type of homocomponent or bicomponent, and more effective sound absorption with bicomponent fibers is obvious. Higher sound absorption coefficients were provided with multilayer nonwoven

The reason for these results may be because the different porosity, tortuosity, and roughness of bicomponent and homocomponent structures. Higher value of tortuosity would therefore indicate longer, more complicated, and sinuous path, thus resulting in greater resistance to sound wave flow. Tortuosity also directly influences propagation of acoustic waves and absorbance efficiency in fibrous porous media. It has also been said that the degree of tortuos-

Additionally, sound absorbent materials must be porous in order to allow sound waves to enter, spread, and decrease sound energy through friction. However, closed pores in the structure have little effect on the absorption of sound, while open pores directly affect the sound insulation properties of the material as they allow sound waves to penetrate into the material

It can be stated that this effect increases with the contribution of bicomponent fibers in the formation of nonwoven surface with filament laying methods, which constitute the basic character of the process of random fiber orientation and intersection [31–34]. As a result, while

ity determines the high frequency behavior of sound absorbing porous materials.

that sound absorption has an inverse relation with air permeability and pore sizes.

**diameter**

**Sound absorption**

This research has been supported by Scientific Research Project Department of Cukurova University. The authors would like to thank also Mogul Nonwoven Company/Gaziantep/ Turkey for supplying nonwoven samples.
