The objective of this paper was to find out how the ratios of longitudinal sound velocity to transverse would play a role as acoustical indicators. These indicator ratios have been investigated due to independent factors of stabilized specific gravity, ring-width and extractives content and were defined in terms of damping and acoustical coefficient in timbers from "Morus alba " and "Cupressus arizonica " of plantations in Iran. The former species has traditional use in Iranian musical instruments and the latter has been subjected in a research on proposing the wood in future performances. Experiments have been done in 5 repetitions (5 different individuals of each species) in different locations from pith to bark of the trunk. In Cupressus specimens as a soft wood, the main definition was in term of reverse correlation between indicator ratios and tandelta {damping). Higher ratios were subjected to lower tandelta which were affected with ring-width variations. No significant correlation was identified between indicator ratios and acoustical coefficient in Cupressus specimens. Narrower rings observed in specimens with smaller damping and higher indicator ratios. But in Morus specimens as a hard wood, higher values of indicator ratios showed higher values of acoustical coefficient which were affected with Extractive content variations. In contrast to Cupressus, no significant correlation was identified between indicator ratios and damping in Morus specimens. Smaller amount of extractive content observed in specimens with higher indicator ratios and acoustical coefficient.
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