"A Swedish study conducted by the University of Lulea's The Acoustic Group found that there is only a six decibel difference between metal and shingle roofs when rain falls on them. Also, a metal roof's wooden deck, foam boards, and attic insulation will further diminish such sounds. If you're thinking about replacing your old roof with a metal roofing system, you should get in touch with a trusted contractor like Arry's Roofing Services, Inc. that can explain or maybe even show you the benefits of a metal roof in Tampa and dispel any concerns or misconceptions you might have."
http://www.arrysroofing.com/info-articles/dont-let-myths-hold-you-back-from-getting-metal-roofing-in-tampa/