Modal parameters of resonant spruce wood (Picea abies L.) after thermal treatment

For a resonant spruce wood (Picea sp.) the acoustic parameters (resonant/ modal frequency (f) and logarithmic decrement (δ)), were determined before and after thermal modification at 160 °C. The material studied came from the Romanian Carpathian mountains and was classified by luthiers as good and very good resonant wood. Thermal modification did not result in significant changes in the number of modes, but differences in the modal frequencies for individual modes were noted. Thermal modification also decreased the logarithmic decrement in the highest quality material.