I had one once that sounded like a Harley at full throttle...
As mentioned above, the water lines can be a contributing factor. One of mine was loose and it banged against a wall with every surge of the pump. Some oversize plastic pipe clamps and some medium density sponge foam around the water line helped a lot. Also tucking that same foam between the water lines and floor / walls too.
In addition to that, my pump was mounted directly to the floor. I removed the screws, got a square of firm, but not rigid foam / rubber and used it as an insulator to the floor.
It helped a lot but the sound will always be there. You can't get away from the sound of the pump itself.
We leave our pump turned off at night, and don't flush until the morning. No big deal there, a little extra liquid in the bowl until morning.