Development and Experiment of Narrowband Active Noise Equalizer

Abstract

This paper presents a narrowband active noise equMizer (ANE) that can either amplify or attenuate acoustic narrowband noise. The output of the ANE system contains residual narrowband noise components, the amplitudes of which can be linearly and arbitrarily controlled by adjusting the gain parameter of the ANE, thus providing the desired noise shaping capability. Each ANE consists of a sinusoidal reference input, a gain parameter and two adaptive weights. A novel pseudo error minimum method is developed to effectively use the least mean square algorithm. Simulations were conducted to verify effectiveness of the algorithm and validity of the analysis. Real-time ANE experiments implemented on a DSP56001 system board have also been presented.

Frequency-domain periodic active noise control and equalization

“…The residual noise spectrum can be reshaped arbitrarily by the periodic ANE with the designed gain vector . A more detailed analysis of the time-domain ANE algorithm can be found in [15].…”

“…The output of the ANE system contains residual narrowband components, the amplitudes of which can be linearly and arbitrarily controlled by adjusting the gain parameter of the equalizer, thus providing the desired noise shaping capability. In this section, the concept of the time-domain asynchronous ANE [15] is applied to the frequency-domain synchronous technique discussed in the previous section.…”

“…The steady-state system transfer function from to at the th frequency bin can be expressed as (15) Therefore, the frequency-domain adaptive filter employing a periodic train of impulses with period as reference signal acts as a comb filter for removing narrowband components in the primary noise.…”

“…The time-domain narrowband ANE, which can either amplify or attenuate narrowband noise, is developed and analyzed in [15]. The output of the ANE system contains residual narrowband components, the amplitudes of which can be linearly and arbitrarily controlled by adjusting the gain parameter of the equalizer, thus providing the desired noise shaping capability.…”

“…This demand leads to an extension of the ANC scheme to noise equalization. Unfortunately, the concept of narrowband adaptive noise equalization (ANE) [15] cannot be directly extended to the time-domain waveform synthesis method. This paper shows that the periodic ANE can be implemented in the frequency domain for synchronously sampled systems.…”