This paper concentrates on modeling the gear transmission system using a three-dimensional finite-element approach for the acoustic radiation analysis and control. The combination of dynamic analysis and vibration response calculation for the gear engagement system can contribute to evaluate acoustic radiation. A case study of for gear engagement system internally excited with gear mesh fluctuation is presented in this research. Acoustic radiation quantity investigation has been carried out by Virtual.Lab Acoustics software. It can be concluded that numerical simulation is very important during gear system design and noise control.