spectrum analyze s 12 and compute the frequency of s 1 fig2 is a schematic diagram of hardware configuration of a system for computing the frequency of a low frequency vibration wave in accordance with another preferred embodiment in the embodiment the system may include computer 1 installed with the vibration wave analyzing software two vibration wave generating devices for example a car engine 6 and a toy car engine 7 laid contiguously a vibration wave sensor 5 connected with computer 1 the two vibration wave generating devices are used for generating a high frequency vibration wave and a low frequency vibration wave correspondingly the high frequency vibration wave and the low frequency vibration wave are mixed together to generate an interference vibration wave vibration wave sensor 5 is used for recording the interference vibration wave into computer 1 computer 1 is used for analyzing the interference vibration wave via the vibration wave analyzing software fig3 is a schematic diagram of the high frequency wave s 2 and the low frequency wave s 1 a sinusoidal function expression of s 1 is shown as follows in the sinusoidal function expression of s 1 the variable f 1 denotes the frequency of s 1 and the variable t denotes a time slice a sinusoidal function expression of s 2 is shown as.