Does the 12 ft. SM-Rib Galvalume Steel 29-Gauge Roof/Siding Panel make a lot of noise when it's raining?

If there is no substrate or just purlins, there will be echoes from the rain.

This is a common misconception about metal roofing. The insulation, decking, and underlayment materials absorb the the noise. If there is no substrate or just purlins, there will be echoes from the rain.