The water flowing to the drain is where the noise usually comes from. A couple tricks may help.
1: Check your water pressure, harmonics and water flow velocity can create serious noise problems. The water pressure should be set to 50-60 PSI in the house. This may help, especially if the pressure is higher than 60 PSI.
2: Larger drain line, water velocities above 8 FPS are a common cause of noise. If you run the drain in 1/2 or 3/4" PVC, this may also help.