Role of Acoustic Properties in Biomedical Active Noise Control

2020 ◽  
Vol 9 (1) ◽  
pp. 48-60
Author(s):  
Sajil C. K. ◽  
Achuthsankar S. Nair
Keyword(s):  
Numerical Simulation ◽  
Biomedical Applications ◽  
Noise Control ◽  
Active Noise Control ◽  
Acoustic Properties ◽  
Reflection Coefficients ◽  
Sensors And Actuators ◽  
Active Noise ◽  
Source Signal

Active noise control (ANC) systems are tailored for user-specific scenarios which are required in biomedical applications due to the physical restrictions in the placement of sensors and actuators. This study examines the role of spectral flatness of acoustic channels and room reflection coefficients in ANC performance. Each room has a unique characteristic response in transforming a source signal. By employing preliminary measurements and numerical simulation, the authors show that improved noise control is possible by optimizing room reverberation and spectral flatness of the secondary acoustic channel. This result has potential application in improving existing ANC systems in biomedical applications like fMRI.

Noise Reduction in Ducts Achievable by Point Control

1998 ◽  
Vol 120 (2) ◽  
pp. 216-223 ◽  
Author(s):  
K. A. Morris
Keyword(s):  
Noise Reduction ◽  
Closed Loop ◽  
Noise Control ◽  
Active Noise Control ◽  
Practical Interest ◽  
Noise Levels ◽  
Sensors And Actuators ◽  
One Dimensional ◽  
Active Noise ◽  
Point Control

Noise control in a one-dimensional duct is analyzed. This problem is of practical interest and is also simple enough that a complete theoretical analysis is possible. It is shown that the optimal controller leads to an unstable closed loop. The noise reduction level achievable with a stable closed loop is calculated for arbitrary choices of sensor and actuator locations. This enables the best placement of sensors and actuators to be determined. Also, the analysis indicates that a “spatial waterbed” effect exists in some configurations of active noise control: i.e., that noise levels are increased for points outside of the region over which the design is done.

SIMULATION OF ACTIVE NOISE CONTROL IN ENCLOSURES USING DIRECT SOUND FIELD PREDICTION

2009 ◽  
Vol 17 (01) ◽  
pp. 83-107 ◽  
Author(s):  
CHRISTOPHER G. PROVATIDIS ◽  
SPIRIDON T. MOUZAKITIS ◽  
GEORGE N. CHARALAMPOPOULOS
Keyword(s):  
Boundary Conditions ◽  
Noise Control ◽  
Active Noise Control ◽  
Sound Field ◽  
New Method ◽  
Test Case ◽  
Sensors And Actuators ◽  
Sound Fields ◽  
Secondary Sources ◽  
Active Noise

This paper is concerned with the active control of sound fields in enclosures. Specifically, the numerical problem of determining the optimum locations of control sensors and actuators is addressed. A new method for determining the optimum secondary sources strength is proposed, based on the explicit prediction of the sound field, which makes the simulation of realistic acoustical applications feasible, in terms of the enclosure's boundary conditions. The irregular geometry of a car cabin with complex boundary conditions is used in order to demonstrate the application of the new method to a test case where the existing methods cannot theoretically apply without resolving to significant numerical error. The new method of determining the secondary sources strength is combined with a modified genetic and a gradient optimization algorithm so as to locate the optimum positions of active noise control transducers for global sound field control. The overall algorithm, constituting of the method for calculating the secondary sources' strength and the optimization algorithms, is adjusted with computational improvements for better performance.

Modelling and simulation of active noise control in a small room

2016 ◽  
Vol 24 (3) ◽  
pp. 607-618 ◽  
Author(s):  
Fauzi Aslan ◽  
Roshun Paurobally
Keyword(s):  
Control System ◽  
Noise Control ◽  
Single Channel ◽  
Active Noise Control ◽  
Single Frequency ◽  
Frequency Noise ◽  
Sensors And Actuators ◽  
Multichannel System ◽  
Active Noise ◽  
Small Room

This paper presents the modeling and simulation results of active noise control (ANC) in a small room using the wave-based approach defined by particle velocities and sound pressure within the defined boundary conditions. The ANC system excitation is a single-frequency noise with an adaptive feedforward configuration. The Finite Difference Time Domain (FDTD) algorithm is used to model the room acoustics due to a boxed loudspeaker of single frequency. A control system based on the filtered-x least mean-squared (FxLMS) algorithm is utilized to synthesize a cancelling noise using a secondary loudspeaker. The single channel system is modified into a multichannel system and genetic algorithm (GA) is used to optimize the sensors and actuators placements simultaneously. Numerical results are plotted to demonstrate the performance of the control system. These show that the numerical modelling technique can be used to combine room acoustic simulation and FxLMS adaptive control. This provides a way for the optimum placement of the microphones and loudspeakers before being used in a practical complex enclosure.

Sign in / Sign up

Export Citation Format

Share Document