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.

Issue Section:
Technical Papers
Keywords:
feedforward, acoustic wave absorption, active noise control, acoustic signal processing, FIR filters, IIR filters
Topics:
Control equipment, Ducts, Feedforward control, Filters, Finite impulse response filters, Acoustics
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.
Copyright © 2001
 by ASME
You do not currently have access to this content.