Characteristics of sounds generated from vapor permeable water repellent fabrics by low-speed frictions

To investigate the sound properties by low-speed frictions (0.2 m/s and 0.5 m/s) which occur when two fabrics are rubbed by wearer's slow movement, six specimens are selected by cluster analysis among seventy-one vapor permeable water repellent fabrics for outdoor sportswear. Their sound spectra are obtained from the FFT analysis. Physical sound properties (LPT, ΔL, Δf) and Zwicker's psychoacoustic parameters - loudness(Z), sharpness(Z), roughness(Z), and fluctuation strength(Z) - are calculated from the sound spectra. Mechanical properties of the fabrics are measured with the KES-FB system. The amplitudes of the sound spectra of all the specimens at 0.5 m/s are higher than those at 0.2 m/s throughout the entire range of frequencies. As the frictional speed changed from 0.2 m/s to 0.5 m/s, the LPT increases about 16 dB, and the loudness (Z) and fluctuation strength (Z) increase about 3 times and 2 times, respectively. The SMD and Weight at the two low frictional speeds are the important factors which affect the sound properties of vapor permeable water repellent fabrics.