Prediction models for audible distance using mechanical and psychoacoustic parameters of combat uniform fabrics

A short audible distance for the rustling sound of combat uniform fabric helps to reduce soldiers' exposure to the enemy forces. The objectives of this study were to evaluate mechanical properties and sound characteristics of combat uniform fabrics, to investigate their influence on audible distance at which fabric's rustling sound can be reached to human ear, and to establish prediction models for audible distance using mechanical and psychoacoustic parameters. Six types of combat uniform fabrics were used as test specimen. Mechanical properties of the specimens were measured according to the KES-FB system and the acoustic characteristics of the fabrics were analyzed by the Sound Quality System. Audible distances of the fabric sounds were assessed by 30 male soldiers. The audible distances were determined by the distance of which the participants walked away from a starting point in a straight line until they could not hear the sound. Water repellent finished fabric (W-WR), which showed the highest values of bending rigidity, shear stiffness, sound pressure level, loudness(Z) and sharpness(Z) among all fabrics, had the longist audible distance. Fabric for summer season (W-S) had the shortest audible distance in all frictional speed levels, which indicates the best auditory camouflage performance. Coefficient of friction was chosen as the variable affecting loudness(Z) of fabric sounds. Loudness(Z) was finally chosen as the prediction parameter for the audible distance by path analysis.