二胡是中國傳統樂器中最主要的擦弦樂器，它的優越性為聲音強弱易於控制自如，善於演奏滑音而接近語言聲腔，能表現出各種喜怒哀樂的情感，適合與多種樂器配合，亦是良好的獨奏樂器。雖然二胡已成為目前主流的樂器之一，但是對於二胡的研究及改良大多仍利用主觀判斷的方式來尋找問題的癥結，再以嘗試錯誤法來解決問題。

二胡演奏所產生的狼音現象及原因，多家說法不一，大多數僅做現象描述，而缺乏科學分析。本研究證實了二胡的狼音並非是受短弦之振動影響而產生的，而係與提琴家族之狼音同為〝拍擊〞現象，但就其產生之原因而言，二胡是因琴弦的自然頻率跟琴皮的自然頻率相近而產生共振，與提琴家族中係因琴弦之自然頻率接近琴板之自然頻率（主木共振）時所產生之情況相類似。此外，目前使用止音布來消除狼音，其附帶之缺點是會使得二胡之高音音量變弱，並非最佳解決方案，所以仍須繼續探究。

本文並嘗試運用有限元素分析軟體ANSYS，建立簡單之琴弦振動模型，將琴碼及琴皮對振動之影響考慮進去，以模擬琴弦之振動模態，以為後續之相關研究預作準備。

Being the main wiping-the-string instrument of Chinese traditional musical instrument, erhu is extraordinarily good on controlling the strong or weak of voices, also on performing glide to simulate human lingual sound, therefore may easily express various emotions such as anger or happiness. It is not only suitable for harmonizing with multiform instruments, but also excellent for playing solo.
Even though erhu has already become main stream of musical instruments nowadays, it still has a lot of defects to settle. At present, the research and refinement of erhus are mostly based on subjective determination of existing problems, and then solve the problems by the method of trial and error.
There are various theories on the phenomenon and causes of wolf-tone resulted from playing erhu, which mostly focus on description of the phenomenon instead of scientific analysis. This thesis intends to proof through theory and experimentation that the wolf–tone is not resulted from vibration effect of short string, but caused by “beating” similar to the violin family. The wolf–tone of erhu caused by beating is resulted from nearly the same natural frequency of the snakeskin as the string, which is like the wolf–tone frequency caused by the main wood resonance frequency on the family of violin instruments, so as to bring the periodic diminution and augmentation of the odd harmonics of a string. The present usage of cloth damper to clear up wolf–tone sounds is not the best resolution because it will weaken the high pitch voice, which must be further keep on exploring.
This thesis also intends to create a string oscillate mode through ANSYS software of finite element method, and to consider the influence on vibration of bridge and snakeskin to imitate string vibration, in order to be prepared for further research.

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