EFFECTS OF SPECIES AND GROWTH RING ANGLES ON ACOUSTIC PERFORMANCE OF

摘要

In this study, effects of wood species and growth ring angles of small wood beams cut from quartersawn boards on vibration efficiency indices were evaluated. Experimental results indicated that growth ring angles (0 degrees, 60 degrees, 90 degrees, and 150 degrees) and wood species (Sitka spruce, Sichuan spruce, Lijiang spruce) had significant effects on vibration efficiency indices. Wood beam samples with 90 degrees growth ring angles showed better acoustical performance than those with 0 degrees growth ring angles followed by samples with growth ring angles of 150 degrees and 60 degrees. Sitka spruce samples had better acoustic performance than Lijiang spruce samples followed by Sichuan spruce. Sitka spruce samples with 90 degrees growth ring angles had the highest mean specific modulus of 33.8 MPa m(3) kg(-1), acoustic vibration efficiency of 5.4 MPa m(3) kg(-1), and conversion efficiency of 710 m(4) kg(-1) s(-1) and the lowest loss tangent of 6.3 x 10(-3). Specific modulus tends to be less sensitive in detecting mean differences among wood samples compared with the other three vibration efficiency indices evaluated in this study. Loss tangent, conversion efficiency, and relative acoustic vibration efficiency yield the same results if they are used as the indices to quantify sound performance of solid wood used as instrument soundboards