Another thing to note is that during a heavy rainstorm a metal roof is much less prone to failure versus a regular roof.
Shingle roof noises.
Spray foam insulation added to the attic ceiling immediately opposite the roof will keep the wood frame and rafters at a more steady temperature.
The patter or even the roar of falling rain or hail popping and cracking noises perhaps due to thermal expansion and contraction of roof coverings metal roofing or roof structure and transmitted noises from other external sources such as low flying aircraft or nearby.
The roof will not collapse or break down because of this.
Roof noises may be described as those attributed to an obvious source.
Insulate your ceiling the denser the barrier between your roof and your interior space the less noise you will hear.