Abstract
A hybrid active sound quality control system, in which a hybrid feedforward and feedback structure is applied, can not only be used in cases where the line-spectrum noise is obtained easily with reference sensors, but it can also improve the comfortability of noise and eliminate unexpected Gaussian random noise. However, the traditional structure for a hybrid active sound quality control system, whereby a reference signal in the feedback control structure is synthesized by the output signals of the feedforward control filter, feedback control filter, and line-spectrum noise cancellation control filter, introduces couplings of the three control filters. To remove the coupling interactions of the feedforward and feedback control structures and to reduce the complexity of the control system, two modified structures with less computational complexity or a smaller increase in computation are investigated in this paper. The first one involves a simplified structure in which the reference signal in the feedback control structure is replaced by the summation of the residual error signal and the output signal of the line-spectrum noise cancellation control filter, and the second one is a modified structure which integrates the output signals of the feedback control filter and the line-spectrum noise cancellation control filter for the reference signal in the feedback control structure. Numerical simulations are carried out to show the performance of the modified structures. The results illustrate that the two modified structures have the ability to cancel Gaussian random noise and to reduce or enhance the amplitude of line-spectrum noise to promote sound quality. Moreover, a simplified structure with a new leaky filtered-x least mean square (FxLMS) algorithm is proposed to upgrade the noise reduction performance and elevate stability in the feedback control structure. The effectiveness of the proposed algorithm also is proven by the simulation results.
Highlights
Active noise control (ANC) technology is mainly applied to reduce the low-frequency noise at points or zones inside a sound field, such as the area near human ears [1,2,3]
Unlike the feedforward control system, the feedback ANC system does not need a reference sensor to acquire the primary noise information, and the reference signal is the summation of the error signal and the control filter output signal filtered by the estimated model of the secondary path [17,18]
The reference signal in the feedback structure is synthesized by three different signals: the residual error signal, the output signal of the line-spectrum noise cancellation control filter, and the total output signal filtered by the estimated model of the secondary path [15]
Summary
Active noise control (ANC) technology is mainly applied to reduce the low-frequency noise at points or zones inside a sound field, such as the area near human ears [1,2,3]. Unlike the feedforward control system, the feedback ANC system does not need a reference sensor to acquire the primary noise information, and the reference signal is the summation of the error signal and the control filter output signal filtered by the estimated model of the secondary path [17,18]. The traditional hybrid sound quality control algorithm includes a feedforward structure, a feedback structure, and a line-spectrum noise cancellation control structure. The reference signal in the feedback structure is synthesized by three different signals: the residual error signal, the output signal of the line-spectrum noise cancellation control filter, and the total output signal filtered by the estimated model of the secondary path [15]. The reference signal of the feedback control structure is replaced by the summation of the residual error signal and the output signal of the line-spectrum noise cancellation control filter. In order to improve the performance of the leaky FxLMS algorithm in the simplified feedback ANC system, a simplified structure with a new leaky FxLMS algorithm is proposed to upgrade the noise reduction and elevate stability in the feedback control structure
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