The active control technique for broadband attenuation of noise in ducts, using spatially feedforward structure, is investigated from the viewpoints of both acoustic analysis and control engineering. According to the previous work by Munjal and Eriksson [1], there exists an ideal controller for this problem. The ideal controller is a function of the finite source impedance and is thus independent of the boundary conditions. Despite the simplicity, the ideal controller cannot be practically implemented due to the difficulty of calibration of electro-mechanical parameters. To overcome the problem, the controller is implemented via an equivalent formulation modified from the controller originally proposed by Roure [2]. The modified controller is implemented on a DSP platform, using a FIR filter, an IIR filter and a hybrid filter. The experimental results showed that the system achieved 17.2 dB maximal attenuation in the frequency band 300∼600 Hz. Physical insights and design considerations in implementation phase are also discussed in the paper.

1.
Munjal
,
M. L.
, and
Eriksson
,
L. J.
,
1988
, “
An Analytical, One-dimensional, Standing-Wave Model of a Linear Active Noise Control System in a Duct
,”
J. Acoust. Soc. Am.
,
84
, pp.
1086
1093
.
2.
Roure
,
A.
,
1985
, “
Self-adaptive Broadband Active Sound Control System
,”
J. Sound Vib.
,
101
, pp.
429
441
.
3.
Elliott
,
S. J.
, and
Nelson
,
P. A.
,
1993
, “
Active Noise Control
IEEE Signal Process. Mag.
,
10
, No.
4
, pp.
12
35
.
4.
Kuo, S. M., and Morgan, D. R., 1995, Active Noise Control Systems: Algorithms and DSP Implementations, Wiley, New York.
5.
Bai
,
M. R.
, and
Lee
,
D. J.
,
1997
, “
Implementation of an Active Headset by using the H Robust Control Theory
,”
J. Acoust. Soc. Am.
,
102
, No.
4
, pp.
2184
2190
.
6.
MacMartin
,
D. G.
, and
Hall
,
S. R.
,
1991
, “
Structural Control Experiments Using and H Power Flow Approach
,”
J. Sound Vib.
,
148
, No.
2
, pp.
223
241
.
7.
Hong
,
J.
, and
Bernstein
,
D. S.
,
1998
, “
Bode Integral Constraints, Colocation, and Spillover in Active Noise and Vibration Control
,”
IEEE Control Syst. Tech.
,
6
, pp.
111
120
.
8.
Desoer, C. A., and Kuh, E. S., 1969, Basic Circuit Theory, McGraw-Hill, New York.
9.
Clark
,
R. L.
, and
Bernstein
,
D. S.
,
1996
, “
Hybrid Control: Separation in Design
,”
J. Sound Vib.
,
214
, No.
4
, pp.
784
791
.
10.
Bai
,
M. R.
, and
Lin
,
Z.
,
1998
, “
Active Noise Cancellation for a Three-dimensional Enclosure by Using Multiple-Channel Adaptive Control and H Control
,”
ASME J. Vibr. Acoust.
,
120
, pp.
958
964
.
11.
Tomizuka
,
M.
,
Tsao
,
T. S.
, and
Chew
,
K. K.
,
1989
, “
Analysis and Synthesis of Discrete-time Repetitive Controllers
,”
ASME J. Dyn. Syst., Meas., Control
,
111
, pp.
353
358
.
12.
Swinbanks
,
M. A.
,
1973
, “
The Active Control of Sound Propagation in Long Ducts
,”
J. Sound Vib.
,
27
, pp.
411
436
.
13.
La Fontaine
,
R. F.
, and
Shepherd
,
I. C.
,
1983
, “
An Experimental Study of a Broadband Active Attenuator for Cancellation of Random Noise in Ducts
,”
J. Sound Vib.
,
91
, No.
3
, pp.
351
362
.
14.
Beranek, L. L., 1996, Acoustics, Acoustical Society of America, Woodbury, NY.
15.
Bai
,
M. R.
, and
Wu
,
H. P.
,
1998
, “
Robust Control Design of a Sensorless Bass-enhanced Moving-Coil Loudspeaker System
,”
J. Acoust. Soc. Am.
,
105
, pp.
3283
3289
.
16.
Juang, J. N., 1994, Applied System Identification, Prentice-Hall, Englewood Cliffs, NJ.
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