本研究透過特別設計的實驗裝置，在控制各種弓毛狀態，配合不同的負載與運弓速度之操作條件，以非接觸式雷射都卜勒技術量測小提琴弦（G弦與E弦）的摩擦振動訊號。運用希爾伯特－黃轉換處理，這種具有非線性與非穩態特性的時頻訊號，經總體平均模態分解技術處理成數個本質模態函數分量後，再計算各分量的頻譜及其自相關函數。實驗結果除了說明弓毛塗抹松香以提高接觸表面黏滯力的重要性外，亦探討琴弦之振動特性與音質的關係，最後並根據實驗結果歸納出評價琴弓品質的判斷準則。 This study used a unique test rig to measure the friction-induced vibration of a violin's strings by a non-contact laser Doppler vibrometer. The state of the contact surface, the normal load, and the sliding speed of the bow on two different strings, i.e. G and E strings, were investigated. Hilbert-Huang transform with ensemble empirical modal decomposition was implemented to calculate the intrinsic modal functions of these vibration signals. The role of robin on the bow and the characteristic of the string's vibration as the origin of a violin's sound were discussed. In conclusion, the guidelines for evaluating the quality of a violin's bow were addressed.