本研究主旨係在探討使用激發古典吉他後擷取的脈衝響應以及頻譜資料，製作出
能將兩把古典吉他音色轉換的轉移函數。我們使用不同激發方法以及感測器來擷取古
典吉他之脈衝響應以及頻譜資料，並使用頻譜相除法製做出能轉換音色的轉移函數，
並對兩把古典吉他完成音色轉換。研究中使用了三種激發方法來擷取古典吉他的脈衝
響應以及頻譜資料，分別是垂直面板撥絃法、氣球脈衝聲波法和喇叭播放白噪音法。
透過比較這些方法，我們得出了以下結論。
首先，比較了使用三種激發方法製作的轉移函數。結果顯示，這些方法都能成功
激發出古典吉他的音孔共振頻率。但在觀察頻譜時，氣球脈衝聲波法和喇叭播放白噪
音法出現了高頻噪聲過大和非目標還原音色的頻率峰值。由於垂直面板撥絃法的頻譜
呈現較低的噪聲，也較適合用於激發古典吉他。
其次，我們比較麥克風和雷射測距儀兩種感測器擷取的脈衝響應以及頻譜資料所
製作的轉移函數。在同樣使用垂直面板撥絃加總法時，不論是麥克風擷取還是雷射測
距儀製作的轉移函數，都能成功轉換古典吉他的音孔共振頻率峰值。但麥克風製作的
轉移函數在還原音孔共振頻率的能量上相對較弱，而雷射測距儀製作的轉移函數能夠
更好地還原音孔共振頻率。
最後，我們使用互相關和重疊積分的結果，來評估麥克風和雷射測距儀所製作的
轉移函數的音色還原效果。結果顯示，雷射測距儀所製作的轉移函數具有較高的互相
關性和重疊積分值，這表明雷射測距儀所製作的轉移函數能夠更準確地還原古典吉他
的音色。

The main objective of this study is to generate the transfer function capable of
transforming the timbre of two classical guitars using the impulse responses captured after
exciting the classical guitars. We employed different excitation methods and acoustic sensors
to capture the impulse response of the classical guitars and to generate the transfer function
for tone transformation between two guitars. Subsequently, we applied this transfer function
to achieve tone transformation between the two classical guitars. Three excitation methods
were used to capture the impulse response of the classical guitars: vertically plucking, balloon
pulse sound wave, and white noise excitation by loudspeaker. Through a comparison of these
methods, the following conclusions were drawn:
Firstly, a comparison was made between the transfer functions produced using the three
excitation methods. The results demonstrated that all these methods were successful in
exciting the air resonant frequencies of the classical guitars. However, when observing the
spectral data, the balloon pulse sound wave and white noise excitation by loudspeaker
exhibited excessive high-frequency noise. The vertically plucking method, on the other hand,
showed the lower noise levels and was more suitable for exciting the classical guitars.
Secondly, we compared the transfer functions created from the impulse response
captured by two different acoustic sensors: microphone and laser displacement sensor. The
transfer function generated by both methods can successfully transform the air resonant
frequency peaks of the classical guitars.
Finally, we evaluated the tone restoration by the transfer functions produced by the
microphone and the laser displacement sensor using the cross-correlation and the overlap
integral. The results indicated that the transfer function generated by the laser displacement
sensor exhibited higher cross-correlation and overlap integral values, suggesting that the use
of the laser displacement sensor could restore more accurately the tone of the classical guitars.

參考文獻
1. San Martín, R., et al., Impulse source versus dodecahedral loudspeaker for measuring parameters derived from the impulse response in room acoustics. The Journal of the Acoustical Society of America, 2013. 134(1): p. 275-284.
2. Meng, Q., et al. Impulse response measurement with sine sweeps and amplitude modulation schemes. in 2008 2nd International Conference on Signal Processing and Communication Systems. 2008. IEEE.
3. Rossing, T.D. and T.D. Rossing, Springer handbook of acoustics. 2014: Springer.
4. 傀儡, 讓 IR 把台北流行音樂中心搬進你的錄音室！, in 樂手巢. 2021/11/25.
5. Lloyd, T., et al., Listener preference towards a real and emulated violin. Journal of New Music Research, 2018. 47(3): p. 270-274.
6. Tones, S. Nad IR Impulse Response Loader.
7. Fricke, J. and K. Lorenz-Kierakiewitz, Room Impulse Response Measurements in Ten Churches of Rome: Hörsamkeit Intelligibility and Possible Suitable Positions for Performances of Church Music. AIA-DAGA 2013 Merano, 2013: p. 2079-2082.
8. Bradley, J., Auditorium acoustics measures from pistol shots. The Journal of the Acoustical Society of America, 1986. 80(1): p. 199-205.
9. Duprat, F., et al., The Acoustic Impulse Response Method for Measuring the Overall Firmness of Fruit. Journal of Agricultural Engineering Research, 1997. 66: p. 251-259.
10. Suministrado, D.C., Acoustic impulse response of young coconut (Cocos nucifera L.) fruits in relation to maturity. Agricultural Engineering International: CIGR Journal, 2021. 23(1): p. 266-273.
11. Bayati, M.R., et al. Evaluation and comparison firmness of “Golab Apple” with two methods of acoustic and penetration during cold storage. 2016.
12. Atre, M.P. and S.D. Apte, Comparison of Impulse Response Methods for Guitar Modeling. IJSEI, 2018. 7(75).
13. Kothe, R.S., Monophonic Musical Instrument Sound Classification Using Impulse Response Modeling. Turkish Journal of Computer and Mathematics Education (TURCOMAT), 2021. 12(5): p. 1667-1672.
14. Martínez, S.N. Measurement of the Impulse Response of the Guitar to Extract Timbre Features. 2019.
15. Atre, M.P. Classification of plucking style and plucking expression of an acoustic guitar notes based on impulse response. in International Conference on Mathematical and Statistical Physics, Computational Science, Education, and Communication (ICMSCE 2022). 2023. SPIE.
16. Havelock, D., S. Kuwano, and M. Vorländer, Handbook of signal processing in acoustics. Vol. 1. 2008: Springer.
17. Skrodzka, E.B., et al., Modal parameters of two incomplete and complete guitars differing in the bracing pattern of the soundboard. The Journal of the Acoustical Society of America, 2011. 130 4: p. 2186-94.
18. MICRO-EPSILON, Catalog optoNCDT laser sensors (Laser displacement sensors - triangulation).
19. MICRO-EPSILON, Instruction Manual optoNCDT 2300.
20. Yudaningtyas, E., ELECTRET CONDENSER MICROPHONE AS SENSOR IN ARTERIAL PULSE RECORDING DEVICE. International Journal of Geomate, 2020. 19.
21. Thompson, S.C., Microphones: A bit of history. The Journal of the Acoustical Society of America, 2023.
22. Microphones, R., Directional Condenser Microphone NTG1 datasheet.
23. Gallagher, T.A., A.J. Nemeth, and L. Hacein-Bey, An introduction to the Fourier transform: relationship to MRI. American journal of roentgenology, 2012.
24. Kreyszig, E., Advanced Engineering Mathematics. 10th ed. 2011/8/16: Wiley.
25. Bracewell, R.N. and R.N. Bracewell, The Fourier transform and its applications. Vol. 31999. 1986: McGraw-Hill New York.
26. Hunt, B., A matrix theory proof of the discrete convolution theorem. IEEE Transactions on Audio and Electroacoustics, 1971. 19(4): p. 285-288.
27. Cochran, W.T., et al., What is the fast Fourier transform? Proceedings of the IEEE, 1967. 55(10): p. 1664-1674.
28. Chaigne, A. and J. Kergomard, Acoustics of musical instruments. 2016: Springer.
29. Adriaensen, F. Acoustical impulse response measurement with ALIKI. in Linux Audio Conference Proceedings. 2006.
30. Türckheim, F., et al. Novel impulse response measurement method for stringed instruments. in Proceedings of 20th International Congress on Acoustics, ICA. 2010.
31. Dirac, P.A.M., The principles of quantum mechanics. 1981: Oxford university press.
32. Ramachandran, K.I., G. Deepa, and K. Namboori, Computational Chemistry and Molecular Modeling: Principles and Applications. 2008: Springer Berlin Heidelberg.
33. Jansson, E., B. Niewczyk, and L. Fryden, On the body resonance C3 and its relation to the violin construction. J. Catgut Acoust. Soc, 1997. 3: p. 9-14.
34. 蘇冠丞, 奈米精密度雷射測距儀量測與比較吉他音色與音量之研究. 臺灣碩博士論文知識加值系統, 2021.