Real time Implementation of a Blind Beamformer for Subband Speech Enhancement using Kurtosis Maximization

B. Sällberg, M. Swartling, N. Grbic, I. Claesson International Workshop on Acoustic Echo and Noise Control, Sep. 2006 This paper presents a real time implementation of a blind beamformer for subband speech enhancement. The beamformer adaptively maximizes the statistical kurtosis measure of the beamformer’s output signal. Speech carries high kurtosis and noise often exhibit lower kurtosis. Hence, maximization of the output signal’s kurtosis enhances speech, in general. The implementation is carried out on a novel framework for real time audio…

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Blind Beamforming Using Parallel Single-channel Speech Enhancers

B. Sällberg, N. Grbic, I. Claesson IEEE ELMAR, pp. 123-126, June 2006 This paper presents an idea to extend a certain class of single channel speech enhancement algorithms to include the spatial domain. The resulting blind beamformer does not rely on a-priori knowledge of source and sensor positions and it enhances one or several speech sources based only on received data. The underlying principle in this approach is the fact that speech signals are short time stationary. Provided that the…

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Applied Methods to Combat Noise in Human Communication

B. Sällberg Blekinge Tekniska Högskola, Licentiate Dissertation 2006:6, June 2006. Acoustic disturbances influence human speech communica-tion by interfering with the communication process. In the worstcase, it is impossible to communicate at all due to these distur-bances. Methods that reduce the influence of the disturbanceswhile preserving speech intelligibility are often desired. This the-sis proposes real-world solutions for applied speech enhancementusing autonomous and robust methods. Most of the work of thethesis concerns solutions to the problem of reducing acoustic dis-turbances within the…

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Implementation Aspects of the Adaptive Gain Equalizer

B. Sällberg, N. Grbic, I. Claesson Blekinge Tekniska Högskola, Research Report 2006:4, Jan. 2006 The quality of speech, or important speech parameters such as the intelligibility, clearness or naturalness of speech, can be emphasized by signal processing. Such processing for improving speech quality can be found in telecommunication applications, e.g. mobile telephony, internet telephony or personal intercom. Blind methods are preferable over conventional because they do not require calibration schemes and are independent of environmental variations. By careful selection of…

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Active Noise Control for Hearing Protection using a Low Power Fixed point Digital Signal Processor

B. Sällberg, L. Håkansson, I. Claesson International Workshop on Acoustic Echo and Noise Control, pp. 65-68, Sep. 2005 This contribution presents a fixed point implementation for acoustical active noise control in hearing defenders. The well known filtered-x least mean squares structure is conformed to fixed point arithmetic and evaluated in real time. The measured performance of the implementation is 20dB to 30dB attenuation of broad band noise and ca 60dB for sinusoidal interference. The implementation uses a low power fixed…

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A Mixed Analog-Digital Hybrid for Speech Enhancement Purposes

B. Sällberg, H. Åkesson, M. Dahl, I. Claesson IEEE International Symposium on Circuits and Systems, vol. 2, pp. 852-855, May 2005 The paper presents and evaluates a hybrid implementation of a low complexity algorithm for speech enhancement, the adaptive gain equalizer (AGE). The AGE is a subband based time domain method for instantaneous boosting of speech. By a combination of digital analysis and analog synthesis, the main advantages of the digital and analog domains are utilized. The hybrid solution is…

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Speech Enhancement Implementations in the Digital, Analog, and Hybrid Domain

B. Sällberg, M. Dahl IEEE Swedish System on Chip Conference, 2005 The general quality of speech or important speech parameters such as the intelligibility, clearness or naturalness of speech can be emphasized by signal processing. Such processing for improving speech quality can be found in telecommunication applications, e.g. mobile telephony, internet telephony or personal intercom. By careful selection of domain for realization, i.e. digital, analog, or hybrid, implementation specific benefits can be utilized to increase the speech quality or performance.…

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Analog Circuit Implementation for Speech Enhancement Purposes

B. Sällberg, H. Åkesson, N. Westerlund, M. Dahl, I. Claesson IEEE 38th Asilomar Conference on Signals Systems, and Computers, vol. 2, pp. 2285-2289, Nov. 2004 Human speech is the main method for personal communication. However, interfering noise could degrade the intelligibility of speech, eventually resulting in errors. Thus, efficient speech enhancement algorithms are needed for example in hand held battery powered hearing aids. This paper presents an implementation of a time domain method for speech enhancement purposes: the adaptive gain…

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Identification and Analysis of Nonlinear Systems

B. Sällberg, H. Åkesson Blekinge Tekniska Högskola, Master Thesis MEE03:32, 2003 In classical mechanical engineering the predominant group of system analysis and identification tools relies on Linear Systems, where research have been carried out for over half a century. Usage of Linear Systems is most widely spread, often due to its simple mathematics and formulation for many engineering problems. Although linearizing is a means for simplifying a problem, it will introduce more or less severe modelling errors. In some cases…

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