Loud splashing sound in sump

[islander84]

I have my 1 1/2” drainline about 6” under water and half a dozen holes drilled in the section under water. The water is making a constant splashing sound where the Water rushes to the surface louder than I prefer. Thoughts on how to quiet this down?

 

[1WildBill]

Do you have any rubble in the Sump where your water comes in?