木理傾斜角與含水率對樂器用材音響性質之影響

Effect of Grain Angle and Moisture Content on Acoustic Properties of Wood for Musical Instruments

黃彥三(Yan-San Huang) ； 陳欣欣(Shin-Shin Chen)

《台灣林業科學》 12卷3期 (1997/09) Pp. 355-361

https://doi.org/10.7075/TJFS.199709.0355

摘要

木材與其他材料相較具有優良的音響特性，自古以來即被用來製作種種樂器：小提琴或鋼琴等弦樂器，係將弦的微弱振動藉由所謂的響板共鳴現象，來達到增幅的擴大效果。由往昔的經驗得知，響板多選用良質雲杉來製作，過去雖有不少有關雲杉音響性質的研究，但大多就木理方向的性質作探討，木理傾斜方向的音響特性則鮮被觸及。本試驗以樂器工廠製作響板用進口北美雲杉為試材，以振動簧片法，測定動粘彈性，探討木理走向及含水率對雲杉各種音響評價指標之影響，其主要結果如次：
1.動彈性係數(E')，損失正切(tan δ)及音響性質評價指標E'/γ,(方程式略)，(方程式略)，(方程式略)及tan δ/E'等之值均隨木理傾斜角φ之增大而明顯變劣。
2.音響特性有隨含水率之增加而變劣之趨勢。

關鍵字

動彈性係數 ； 損失彈性係數 ； 損失正切 ； 音響性質 ； 振動簧片法

並列摘要

The vibrating reed method was used to measure dynamic viscoelastic properties of sitka spruce. Effects of grain angle and moisture content on the acoustic properties of this wood were examined. The test pieces were 120mm in length, 10mm in width and 5mm in thickness. The grain angles ranged from 0° to 90° in intervals of 15°. Moisture contents were controlled at 6%, 12% and 20%. The following results were obtained.
1. Values of dynamic Young's modulus (E'), loss tangent (tan δ) and acoustic properties such as specific elasticity (E'/γ), (The equation is abbreviated), (The equation is abbreviated), (The equation is abbreviated),and tan δ/E' became significantly inferior as grain angle increased.
2. Acoustic properties became inferior as moisture content of wood increased.

並列關鍵字

dynamic Young's modulus ； dynamic loss modulus ； loss tangent ； acoustic properties ； vibrating reed method