This thesis describes effects of input frequency and fibre type on the dynamic compressive behaviour of fibre assemblies. Frequency response measurements on the fibre of four fiber types were carried out at six different frequencies by means of a piston-cylinder device connected to a scotch yoke mechanism. 1. The order in which the peak pressure lines place themselves depends on the fibre types and input frequencies. 2. Under repetitive compression, the observed variation in the peak response level indicates that regardless of the fibre type on orderless fibre mass posess a frequency (turn around frequency in this thesis) at which the peak pressure response level reaches a maximum.