wooden arrows always tend to quieten down a bow and yes, they require heavier spine. after all, carbon and aluminum are hollow tubes and will transmit/generate more sound/noise. wood is a solid, porous, sound absorbing material for the biggest part.
years ago when wood arrows reigned, the standard was measured at 26" between centers for spine testing a wooden shaft. draw length standard for poundage rating was/is 28" (unless specified differently by the mfgr)
if you go to a 28" CTC measurment of spine from 26" CTC, it changes. that's why there's a difference in spine ratings of wood/alum/carbon...basically.