Noise and vibration are the two distinct symbols of today industrial world which have caused serious inconveniences for human both at work and home. Modern world has compled human being to unwanted compromise with noise pollutions. Elimination or reduction of noise pollutions can be achieved using various sound barriers such as needled nonwoven fabrics. The aim of this work is to investigate the effects of variables such as nonwoven mass per unit area and needling adjustments such as punch density and depth of needle penetration on the amount of sound transmitted through the nonwoven needled fabrics made using staple Polypropylene fibers. Sound transmission through the fabric was researched through the effect of variables such as fabric mass and needling parameter on internal fiber orientation and mechanical properties of needled fabrics. This resulted in prediction of the mechanical properties of the fabric using its sound transmission ability. 27 experimental samples were prepared using 17dtex, 90mm commercially available Polypropylene fibers. Nonwoven layers were made on a laboratory carding machine and subsequently were needled on a laboratory needling machine. The samples were made using punch densities of 30, 60 and 90 needle/ and needle penetration depth of 5,10 and 15mm. Impedance tube were used to measure the transmitted sound through the samples. Image processing technique was used to detrimine the internal fiber orientation of the samples. Changes in sound transmission through the samples were measured in terms of fabric mass per ninit area and needling adjustments. It was found that among three parameters namely fabric mass, punch density and depth of needle penetration, fabric mass per unit area had the highest effect on sound reduction and effect of other parameters were only through their influence on mass per unit area of the samples. It was also found that there exists a significant correlation between the mechanical properties due to the the three examined parameters and ability of the sound to be transmitted through the fabric. The investigations showed that highest correlation between sound behaviors of the sample is offered by fabric air permeability. This is followed by other properties such as bending resistance, internal fiber alignment and stiffness respectively. Keywords : noise, vibration, nonwoven, sound transmission loss, depth penetration, orientation, polypropylene, image processing