Non-coherent detection of impulse radio UWB signals based on fourth order statistics

M. G. Khan, B. Sällberg, J. Nordberg, I. Claesson IEEE International Conference on Ultra-Wideband, pp. 824-828, Oct. 2009 Non-coherent receivers are an attractive solution for impulse radio (IR) ultra wideband (UWB) systems due to their low-complexity implementation and low power consumption. However, low-complexity detection is achieved at the expense of some loss in performance. In this paper, a non-coherent detection scheme based on fourth order statistics, i.e., kurtosis is proposed for low data rate IR-UWB systems. The performance of a…

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Statistical Analysis of a Local Quadratic Criterion for Blind Speech Extraction

B. Sällberg, N. Grbic, I. Claesson IEEE Signal Processing Letters, vol. 16, no. 2, pp. 89-92, Feb. 2009 This letter aims at complementing previous empirical work regarding a certain beamforming technique for blind speech extraction that uses a local quadratic approximation of a Kurtosis expression. It is shown here that the proposed method possesses a fixed-point property which means that it remains at an optimal solution once this solution has been reached. The proposed method’s fixed-point property is valid for…

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Applied Methods for Blind Speech Enhancement

B. Sällberg Blekinge Tekniska Högskola, Doctoral Dissertation 2008:15, Dec. 2008 Acoustic disturbances influence human speech communication by interfering with the communication process. In the worst case, it is impossible to communicate at all due to these disturbances. Methods that reduce the influence of the disturbances while preserving speech intelligibility are often desired. This thesis proposes real-world solutions for applied speech enhancement using autonomous and robust methods. Most of the work of the thesis concerns solutions to the problem of reducing…

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Complex-valued Independent Component Analysis for Online Blind Speech Extraction

B. Sällberg, N. Grbic, I. Claesson IEEE Transaction on Audio, Speech and Language Processing, vol. 16, no. 8, pp. 1624-1632, Nov. 2008 This paper presents a theoretical analysis of a certain criterion for complex-valued independent component analysis (ICA) with a focus on blind speech extraction (BSE) of a spatio-temporally nonstationary speech source. In the paper, the proposed criteria denoted KSICA is related to the well-known FastICA method with the Kurtosis contrast function. The proposed method is shown to share the…

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On a Method for Improving Impulsive Sounds Localization in Hearing Defenders Directional Aid for Hearing Defenders: Enhancement of Impulsive Sounds using ILD

B. Sällberg, F. Sattar, I. Claesson EURASIP Journal on Audio, Speech, and Music Processing, Special issue on Intelligent Audio, Speech, and Music Processing Applications, 2008 This paper proposes a new algorithm for a directional aid with hearing defenders. Users of existing hearing defenders experience distorted information, or in worst cases, directional information may not be perceived at all. The users of these hearing defenders may therefore be exposed to serious safety risks. The proposed algorithm improves the directional information for…

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Direction of Arrival Estimation for Speech Sources using Fourth Order Cross Cumulants

M. Swartling, B. Sällberg, N. Grbic IEEE International Symposium on Circuits and Systems, pp. 1696-1699, May 2008 In many applications where speech separation and enhancement is of interest, e.g. conferencing systems, mobile phones and hearing aids, accurate speaker localization is important. This paper presents an alternative criteria for the well known steered response power with phase transform (SRP-PHAT) algorithm, in which the steered response relates to peaks in the fourth order cross cumulant, rather than peaks in the second order…

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An Adaptive Blind Beamformer with an Integrated Single-channel Noise Reduction Method for Robust Realtime Blind Speech Extraction

B. Sällberg, N. Grbic, I. Claesson IEEE International Conference on Acoustics, Speech, and Signal Processing, pp. 309-312, Mar. 2008 The performance of single-channel temporal noise reduction methods generally deteriorate in high noise environments, whereas spatial beamformers can maintain some level of speech enhancement. This paper presents a solution where a low complexity single-channel noise reduction method is integrated into the feedback control loop of an adaptive blind beamformer with the purpose of robust blind speech extraction in high noise environments.…

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Online Blind Speech Extraction based on a Locally Quadratic Kurtosis Criteria and a Preprocessing Automatic Gain Controller

B. Sällberg, N. Grbic, I. Claesson IEEE ELMAR, pp. 139-142, Sept. 2007 This paper focuses on realtime speech extraction using blind adaptive beamforming. The speech extraction is carried out using an approximation of the kurtosis measure in a subband domain. The introduced kurtosis approximation is an improvement of a recently proposed approximation technique where a locally quadratic criterion was solved at each iteration. The improvement introduced in this paper regards an approach to normalize this same criterion using a pre-processing…

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Online Maximization of Subband Kurtosis for Blind Adaptive Beamforming in Realtime Speech Extraction

B. Sällberg, N. Grbic, I. Claesson IEEE 15th International Conference on Digital Signal Processing, pp. 603-606, 2007 This paper presents a method for blind beamforming with application in realtime speech extraction in a non-stationary environment. The blind beamforming is carried out using an online kurtosis maximization approach where the optimization is based on Newton’s method. The main novelty of the paper lies in the formulation of the subband kurtosis approximation, where a locally quadratic criterion is solved at each iteration.…

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Real-Time DSP Implementation of a Subband Beamforming Algorithm for Dual Microphone Speech Enhancement

Z. Yermeche, B. Sällberg, N. Grbic, I. Claesson IEEE International Symposium on Circuits and Systems, pp. 353-356, May 2007 A real-time digital signal processor (DSP) based implementation of a subband beamforming algorithm and its evaluation for dual microphone speech enhancement is presented. The algorithm, a calibrated constrained beamformer, is described theoretically and a real-time structure is proposed, including an efficient approach for multichannel data transformation. Measurements show that the battery driven DSP implementation supports 20 h operation-time, with an improved…

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