本文提出針對動圈式揚聲器的補償系統。補償系統包含前置式補償器、反饋式補償器以及混合式補償器組成。其中，前置式補償器由有限脈衝濾波器實現；反饋式補償器由線性二次高斯法（LQG）設計；混合式補償器則是將前置式補償器與反饋式補償器組合實現。而每種補償系統又分為有感測器式與無感測器式，其中所需的控制器皆為單輸入單輸出系統，最後進行的都是單聲道的喇叭補償。在實驗設計中，前饋補償器先採用離線操作求得補償器係數，再載入數位訊號處理開發版執行；反饋補償器採用模擬電路的方式來實現；將上述兩者串聯即可得到混合式補償器。本文討論模擬驗證與實驗執行，隨後提出客觀與主觀的評估測試，來衡量此補償器之效果。

This paper presents a compensation system for moving coil loudspeakers, which including feedforward compensation, feedback compensation and hybrid compensation. The feedforward compensation is realized by Finite Impulse Response (FIR) filter, feedback compensation is designed by Linear–quadratic–Gaussian (LQG) control, hybrid compensation is combination of feedback controller and feedforward controller. Each compensation system is also divided into two methods: sensor method and sensorless method, all the systems in this paper are single input single output (SISO), so the compensations are also single channel compensations. In experiment design, the feedforward part, we use off-line operations, which calculating compensation coefficients in computer first and then using digital signal processor (DSP) to implement. While in feedback, analog circuits are introduced in this paper. At last, we combine the feedforward and feedback part, and the combination is called hybrid compensation. Besides the verification of simulations and experiments are shown in this paper, we also do objective and subjective tests to measure the effect of compensator.

Table of Contents
摘 要 1
ABSTRACT 2
FIGURE LIST 3
Chapter 1 INTRODUCTION 5
Chapter 2 SYSTEM IDENTIFICATION: ELECTRO-ACOUSTIC ANALOGY CIRCUIT
9
2.1 Circuit Analogy 10
2.2 Electroacoustic Analysis of Moving-coil Loudspeakers 11
2.3 State-space Equation Derived from EMA Circuit 13
FIGURES IN CHAPTER 2 16
Chapter 3 COMPENSATION WITH A SENSOR 19
3.1. Feedforward Compensation 20
3.1.1 Adaptive Filtering 20
3.1.2 Filtered-X LMS 21
3.1.3 Feedforward Structure 22
3.2. Feedback Compensation 23
3.3. Hybrid Compensation 24
FIGURES IN CHAPTER 3 25
Chapter 4 COMPENSATION WITHOUT A SENSOR 30
4.1. Feedforward Compensation 31
4.2. Feedback Compensation 32
4.2.1 Kalman-Bucy Observer 32
4.2.2 Feedback from Estimated States 33
4.2.3 LQG Control 34
4.3. Hybrid Compensation 36
FIGURES IN CHAPTER 4 37
Chapter 5 SIMULATIONS AND EXPERIMENTS 40
5.1. Simulation 41
5.2.1 Feedback Compensation: Op-Amp Circuit Implementation 43
5.2.2 Feedforward Compensation: Fixed-point DSP and Offline Operation 45
5.3. Experiment Results 46
5.3.1 Objective Tests: Comparison of Frequency Response 46
5.3.2 Subjective Tests: Listening Tests 47
FIGURES IN CHAPTER 5 50
Chapter 6 CONCLUSIONS 66
REFERENCES 69
TABLES 73

[1]. C. Busso, "Smart room: participant and speaker localization and identification." Acoustics, Speech, and Signal Processing, 2005. Proceedings. (ICASSP'05). IEEE International Conference on. Vol. 2. IEEE, 2005.
[2]. A. Bright, "Simplified loudspeaker distortion compensation by DSP." Audio Engineering Society Conference: 23rd International Conference: Signal Processing in Audio Recording and Reproduction. Audio Engineering Society, 2003.
[3]. W. J. Klippel, Adaptive nonlinear control of loudspeaker systems. Journal of the Audio Engineering Society, 46.11: 939-954, 1998.
[4]. W. J. Klippel, Compensation for nonlinear distortion of horn loudspeakers by digital signal processing. Journal of the Audio Engineering Society, 44.11: 964-972, 1996.
[5]. J. Borwick, Loudspeaker and headphone handbook. CRC Press, 2012.
[6]. M. R. Bai and C. C. Lee, DSP-based sensorless velocity observer with audio applications in loudspeaker compensation. In: Audio Engineering Society Convention 118. Audio Engineering Society, 2005.
[7]. M. R. Bai and H. P. Wu, Robust control of a sensorless bass-enhanced moving-coil loudspeaker system. The Journal of the Acoustical Society of America, 105.6: 3283-3289, 1999.
[8]. D. K. Anthony and S. J. Elliott, A comparison of three methods of measuring the volume velocity of an acoustic source. Journal of the Audio Engineering Society, 39.5: 355-366, 1991.
[9]. K. Matsuda and H. Hashitani, Self-sensing active vibration control using the moving-coil-type actuator. Journal of Vibration and Acoustics, 117: 411, 1995.
[10]. F. J. Fahy, Foundations of Engineering Acoustics. Academic Press, 2000.
[11]. C. T. Chen, Linear system theory and design. Oxford University Press, 1995.
[12]. B. Widrow, S.D Stearns and J. C. Burgess, Adaptive signal processing. The Journal of the Acoustical Society of America, 80(3), 991-992, 1986.
[13]. S. L. Gay and J. Benesty, Acoustic signal processing for telecommunication. Springer Science & Business Media, 2012.
[14]. S. M. Kuo and D. R. Morgan, Active noise control system. U.S. Patent No 5,359,662, 1994.
[15]. L. Hakansson. The filtered-X LMS algorithm. Department of Telecommunications and Signal Processing, University of Karlskrona/Rooneby, 372: 25, 2004
[16]. M. R. Bai and G. M. Lin, The development of a DSP-based active small amplitude vibration control system for flexible beams by using the LQG algorithms and intelligent materials. Journal of Sound and Vibration, 198.4: 411-427, 1996.
[17]. H. Kwakernaak and R. Sivan. Linear optimal control systems (Vol. 1, p. 608). New York, 1972.
[18]. W. Klippel, The mirror filter-a new basis for reducing nonlinear distortion and equalizing response in woofer systems. Journal of the Audio Engineering Society, 40(9), 675-691, 1992.
[19]. J. Borwick, Loudspeaker and Headphone Handbook, 3rd ed., (Butterworth-Heinemann, Oxford), pp. 16-49, 2011.
[20]. A. Bright, Discrete-time loudspeaker modelling. In Audio Engineering Society Convention 114. Audio Engineering Society, 2003.
[21]. A. J. Mason, The MUSHRA audio subjective test method. BBC R&D White Paper WHP, 38, 2002.