How often should a Ejector Pump kick on. Why does it kick on. Don't they work without making a noise.

They kick on then the pit gets full. How often depends on how much waste water is being dumped into the pit. If you have a leaking check valve it will cycle frequently. How much noise are you talking about? You should hear a motor run, some water noise from the pipes and a thump when the check valve closes.

So we are talking about a bathroom below grade, correct. An ejector pump pumps sewage up to the main drain exiting the home. They are only used for sewage or gray water