Ali A. Milani

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—Subband adaptive filtering (SAF) techniques play a prominent role in designing active noise control (ANC) systems. They reduce the computational complexity of ANC algorithms, particularly, when the acoustic noise is a broadband signal and the system models have long impulse responses. In the commonly used uniform-discrete Fourier transform (DFT)-modulated(More)
Performance of commonly used Hearing aid systems is degraded by the presence of acoustic feedback between loudspeaker and microphone. Prediction Error Method Adaptive Feedback Canceller (PEM-AFC) has been proposed recently that could attenuate the feedback effect. In this paper, we present a new delayless frequency-based sub-band filtering method for(More)
We present application of adaptive LMS-based method using two different sub-band filtering techniques for active reduction of 3T-fMRI acoustic noise. Analysis and design of the sub-band filters are discussed based on the characteristics of the noise. Using the fMRI-brain scanner acoustic noise, performance of the methods are analyzed and compared for(More)
Functional magnetic resonance imaging (fMRI) acoustic noise exhibits an almost periodic nature (quasi-periodicity) due to the repetitive nature of currents in the gradient coils. Small changes occur in the waveform in consecutive periods due to the background noise and slow drifts in the electroacoustic transfer functions that map the gradient coil(More)
Active noise control (ANC) is primarily a signal estimation problem. The nature of noise to be canceled, the acoustic paths, and the transfer functions of microphones/loudspeakers place fundamental limits on the performance of ANC systems. In this paper we analyze the performance of ANC systems from the maximum achievable noise attenuation level (NAL max)(More)
PURPOSE To recover speech corrupted by functional magnetic resonance imaging (fMRI) acoustic noise using two-channel adaptive speech enhancement techniques. MATERIALS AND METHODS Speech corrupted by noise generated from a 3 T MRI scanner was recorded using diffuse-field microphones and a data acquisition board. Multiband and subband adaptive speech(More)
Multichannel speech enhancement has been shown to be an effective method to decrease speech distortion introduced during speech enhancement, especially in environments like MRI (magnetic resonance imaging) which have a distributed noise source. However, these methods suffer from high computational complexity which makes them almost impractical. The use of(More)