The water line coming into house has meter and regulator on it
It is making the loudest noise when water is turned on
How can I stop the noise please

Odds are that it is the pressure reducing valve (regulator). It is either defective or has a build up of debris. Some models have screens that can be removed and cleaned. Otherwise it is replace.

It sounds like a pressure reducing valve,(PRV). Do you know your house PSI?
Try this, Run the water until it starts to make noise. Now turn the adjusting screw up and down a bit to see if the noise stops. Let me know if that works. Good luck, Tom

I am with both Tom and Harold problem is with you PRV, watch the Video blow will show how to adjust and check your water pressure, Thanks.

John

https://www.youtube.com/watch?v=JgxGqQrC6Ds