Much depends on the insulation in the rafter bays.

I've found that fiberglass transmits much more noise than dense-packed cellulose or a couple of inches of foam.

For your reroof, you can strip the existing shingles and add a couple of inches of foam on the TOP of the roof's existing sheathing. Then run your purlins for the metal roof over the foam, and fasten the metal roof to the purlins.

That would be fairly easy to do with minimal fuss.

The specific detailing depends on the climate in which you live.

Mongo

I live in the rain capitol of the U.S....Seattle. I have cathedral ceilings, and a metal roof. It's a newer home and has cellulose roll insulation in the ceilings. I've noticed no difference in noise between this and the cedar shakes at my previous house. Maybe if you were living out in the boonies with a tin roof and no insulation you'd have more noise, but I think it's a non-issue in today's houses. And, from a maintenance standpoint, I'll never go back to a conventional roof

I like the sound of the rain....especially when the metal roof is keeping it outside.

Apparently you can roof over other types, shingle included. It's even legal in some places. Sounds yucky but somewhat practical. If you did it over shingles I doubt you'd hear much.

You do get used to it, anyway. My old house in Sydney Aust had a metal roof over my bedroom, a not-very well done addition - very low ceiling. It really isn't that bad.

I love to hear the sound of rain and in our present home there is so much insulation that you cant hear it! I keep the windows open to hear wind, birds, rain, the sounds of nature instead of the TV and other appliances :)

I think it matters what you have as a ceiling material. I LOVE the sound of rain an a metal roof even if it is loud. Maybe, when it is raining, you could visit someone who has a metal roof?

We are thinking of putting on a stone coatedsteel roof. most of our living area in this house has cathedral ceilings . The house was built 40 years ago. We assume there is insulation there between the ceiling and the roof but are not sure what or how much. A stone coated steel roof would look great on this house. Just concerned about acoustics. We have done other things here to mitigate sound. e.g. new flooiring , better air handlers on hvac, new attic insualtion in the areas that have attic space. don't want to take a step back with a roof. Roofer doesn't think it will be aproblem. BUt not sure. we are removing cedar shakes. Any advice appreciated

I have a metal roof and love it. I live in southern Florida where we have torrential rains and it is very quiet. Our roof has plywood over the trusses, then a moisture barrier of some sort, then the metal. I have pyramidal ceilings in several rooms of my house, so the space between the top of the ceiling and the underside of the roof can’t hold a lot of insulation.
I was wondering about noise before we installed it too, but it has never been an issue.