Sound is a vibration wave picked up by the auditory circuits of the ear. Vibrations are caused by the expansion and compression cycle of a material, or medium, in air. Events of expansion and compression have varying speeds depending on the material, or medium. The speed creates a frequency of vibrational wave; various speeds create various corresponding frequencies. The frequency (speed of vibration) of the tearing of a dry piece of paper is at a vibrational frequency range high enough to be heard by the human ear.
Tearing wet paper vibrates at a lower vibrational frequency that is not as readily heard by the human ear apparatus. Similarly, vibrational rates that are higher than the range the human ear can register are also not heard. In both cases, however, lower than the range the human ear can register and higher than it can register, vibrations occur and vibrational wave frequencies exist.
