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Simon Doclo - One of the best experts on this subject based on the ideXlab platform.

  • comparison of two Binaural beamforming approaches for Hearing aids
    International Conference on Acoustics Speech and Signal Processing, 2017
    Co-Authors: Elior Hadad, Simon Doclo, Daniel Marquardt, Zhiquan Luo, Ivo Merks, Sharon Gannot, Tao Zhang
    Abstract:

    Beamforming algorithms in Binaural Hearing aids are crucial to improve speech understanding in background noise for Hearing impaired persons. In this study, we compare and evaluate the performance of two recently proposed minimum variance (MV) beamforming approaches for Binaural Hearing aids. The Binaural linearly constrained MV (BLCMV) beamformer applies linear constraints to maintain the target source and mitigate the interfering sources, taking into account the reverberant nature of sound propagation. The inequality constrained MV (ICMV) beamformer applies inequality constraints to maintain the target source and mitigate the interfering sources, utilizing estimates of the direction of arrivals (DOAs) of the target and interfering sources. The similarities and differences between these two approaches is discussed and the performance of both algorithms is evaluated using simulated data and using real-world recordings, particularly focusing on the robustness to estimation errors of the relative transfer functions (RTFs) and DOAs. The BLCMV achieves a good performance if the RTFs are accurately estimated while the ICMV shows a good robustness to DOA estimation errors.

  • Speech enhancement for multimicrophone Binaural Hearing aids aiming to preserve the spatial auditory scene
    EURASIP Journal on Advances in Signal Processing, 2016
    Co-Authors: Joachim Thiemann, Simon Doclo, Menno Müller, Daniel Marquardt, Steven Van De Par
    Abstract:

    Modern Binaural Hearing aids utilize multimicrophone speech enhancement algorithms to enhance signals in terms of signal-to-noise ratio, but they may distort the interaural cues that allow the user to localize sources, in particular, suppressed interfering sources or background noise. In this paper, we present a novel algorithm that enhances the target signal while aiming to maintain the correct spatial rendering of both the target signal as well as the background noise. We use a bimodal approach, where a signal-to-noise ratio (SNR) estimator controls a binary decision mask, switching between the output signals of a Binaural minimum variance distortionless response (MVDR) beamformer and scaled reference microphone signals. We show that the proposed selective Binaural beamformer (SBB) can enhance the target signal while maintaining the overall spatial rendering of the acoustic scene.

  • interaural coherence preservation in multi channel wiener filtering based noise reduction for Binaural Hearing aids
    IEEE Transactions on Audio Speech and Language Processing, 2015
    Co-Authors: Daniel Marquardt, Volker Hohmann, Simon Doclo
    Abstract:

    Besides noise reduction an important objective of Binaural speech enhancement algorithms is the preservation of the Binaural cues of all sound sources. To this end, an extension of the Binaural multi-channel Wiener filter (MWF), namely the MWF-ITF, has been proposed, which aims to preserve the Interaural Transfer Function (ITF) of the noise sources. However, the MWF-ITF is well-suited only for directional noise sources but not for, e.g., spatially isotropic noise, whose spatial characteristics cannot be properly described by the ITF but rather by the Interaural Coherence (IC). Hence, another extension of the Binaural MWF, namely the MWF-IC, has been recently proposed, which aims to preserve the IC of the noise component. Since for the MWF-IC a substantial tradeoff between noise reduction and IC preservation exists, in this paper we propose a perceptually constrained version of the MWF-IC, where the amount of IC preservation is controlled based on the IC discrimination ability of the human auditory system. In addition, a theoretical analysis of the Binaural cue preservation capabilities of the Binaural MWF and the MWF-ITF for spatially isotropic noise fields is provided. Several simulations in diffuse noise scenarios show that the perceptually constrained MWF-IC yields a controllable preservation of the IC without significantly degrading the output SNR compared to the Binaural MWF and the MWF-ITF. Furthermore, contrary to the Binaural MWF and MWF-ITF, the proposed algorithm retains the spatial separation between the output speech and noise components while the Binaural cues of the speech component are only slightly distorted, such that the Binaural Hearing advantage for speech intelligibility can still be exploited.

  • coherence preservation in multi channel wiener filtering based noise reduction for Binaural Hearing aids
    International Conference on Acoustics Speech and Signal Processing, 2013
    Co-Authors: Daniel Marquardt, Volker Hohmann, Simon Doclo
    Abstract:

    Besides noise reduction an important objective of Binaural speech enhancement algorithms is the preservation of the Binaural cues, i.e. the Interaural Level Difference and the Interaural Time Difference of all sound sources. Recently, extensions of the Binaural Multi-channel Wiener filter (MWF) have been presented, which aim to preserve the Binaural cues of the residual noise component. However, since these algorithms aim to preserve the Interaural Transfer Function (ITF), they are well-suited only for directional noise sources but not for, e.g. spatially isotropic noise, which can not be fully described by the ITF. In this paper, we present an extension of the Binaural MWF, aiming to preserve the Interaural Coherence of the residual noise component. Experimental results using spatially isotropic noise show that the proposed algorithm yields a good preservation of the Interaural Coherence without significantly degrading the output SNR compared to the Binaural MWF and the Binaural MWF with ITF preservation.

  • speech enhancement with multichannel wiener filter techniques in multimicrophone Binaural Hearing aids
    Journal of the Acoustical Society of America, 2009
    Co-Authors: Tim Van Den Bogaert, Simon Doclo, Jan Wouters, Marc Moonen
    Abstract:

    This paper evaluates speech enhancement in Binaural multimicrophone Hearing aids by noise reduction algorithms based on the multichannel Wiener filter (MWF) and the MWF with partial noise estimate (MWF-N). Both algorithms are specifically developed to combine noise reduction with the preservation of Binaural cues. Objective and perceptual evaluations were performed with different speech-in-multitalker-babble configurations in two different acoustic environments. The main conclusions are as follows: (a) A bilateral MWF with perfect voice activity detection equals or outperforms a bilateral adaptive directional microphone in terms of speech enhancement while preserving the Binaural cues of the speech component. (b) A significant gain in speech enhancement is found when transmitting one contralateral microphone signal to the MWF active at the ipsilateral Hearing aid. Adding a second contralateral microphone showed a significant improvement during the objective evaluations but not in the subset of scenarios t...

Jan Wouters - One of the best experts on this subject based on the ideXlab platform.

  • reduced bandwidth multi channel wiener filter based Binaural noise reduction and localization cue preservation in Binaural Hearing aids
    Signal Processing, 2014
    Co-Authors: Bram Cornelis, Marc Moonen, Jan Wouters
    Abstract:

    Binaural Hearing aids allow for a wireless exchange of microphone signals between a left and a right device. A significant noise reduction performance improvement can be achieved compared to a monaural configuration (a single device) or a bilateral configuration (in which the devices work independently). In addition, the Binaural localization cues, i.e. the Interaural Time Differences and Interaural Level Differences, can also be better preserved in a Binaural procedure. It was previously proven that a Binaural noise reduction procedure based on the Speech Distortion Weighted Multi-channel Wiener Filter (SDW-MWF) indeed preserves the speech localization cues, if all microphone signals can be exchanged. However, in practice, it may not be feasible to exchange all microphone signals between the devices, so that reduced-bandwidth SDW-MWF schemes (where only filtered combinations of microphone signals are exchanged) have to be utilized. This paper demonstrates that a straightforward reduced-bandwidth SDW-MWF scheme still preserves the speech ITD cues, but distorts the speech ILD cues, in a single speech source scenario. Novel reduced-bandwidth SDW-MWF schemes, which make use of a common spectral postfilter, are therefore introduced. Experiments in a reverberant environment demonstrate that the novel schemes reduce the ILD distortion, without severely degrading the noise reduction performance.

  • speech enhancement with multichannel wiener filter techniques in multimicrophone Binaural Hearing aids
    Journal of the Acoustical Society of America, 2009
    Co-Authors: Tim Van Den Bogaert, Simon Doclo, Jan Wouters, Marc Moonen
    Abstract:

    This paper evaluates speech enhancement in Binaural multimicrophone Hearing aids by noise reduction algorithms based on the multichannel Wiener filter (MWF) and the MWF with partial noise estimate (MWF-N). Both algorithms are specifically developed to combine noise reduction with the preservation of Binaural cues. Objective and perceptual evaluations were performed with different speech-in-multitalker-babble configurations in two different acoustic environments. The main conclusions are as follows: (a) A bilateral MWF with perfect voice activity detection equals or outperforms a bilateral adaptive directional microphone in terms of speech enhancement while preserving the Binaural cues of the speech component. (b) A significant gain in speech enhancement is found when transmitting one contralateral microphone signal to the MWF active at the ipsilateral Hearing aid. Adding a second contralateral microphone showed a significant improvement during the objective evaluations but not in the subset of scenarios t...

  • speech enhancement with multichannel wiener filter techniques in multimicrophone Binaural Hearing aids
    Journal of the Acoustical Society of America, 2009
    Co-Authors: Tim Van Den Bogaert, Simon Doclo, Jan Wouters, Marc Moonen
    Abstract:

    This paper evaluates speech enhancement in Binaural multimicrophone Hearing aids by noise reduction algorithms based on the multichannel Wiener filter (MWF) and the MWF with partial noise estimate (MWF-N). Both algorithms are specifically developed to combine noise reduction with the preservation of Binaural cues. Objective and perceptual evaluations were performed with different speech-in-multitalker-babble configurations in two different acoustic environments. The main conclusions are as follows: (a) A bilateral MWF with perfect voice activity detection equals or outperforms a bilateral adaptive directional microphone in terms of speech enhancement while preserving the Binaural cues of the speech component. (b) A significant gain in speech enhancement is found when transmitting one contralateral microphone signal to the MWF active at the ipsilateral Hearing aid. Adding a second contralateral microphone showed a significant improvement during the objective evaluations but not in the subset of scenarios tested during the perceptual evaluations. (c) Adding the partial noise estimate to the MWF, done to improve the spatial awareness of the Hearing aid user, reduces the amount of speech enhancement in a limited way. In some conditions the MWF-N even outperformed the MWF possibly due to an improved spatial release from masking.

  • reduced bandwidth and distributed mwf based noise reduction algorithms for Binaural Hearing aids
    IEEE Transactions on Audio Speech and Language Processing, 2009
    Co-Authors: Simon Doclo, Marc Moonen, Tim Van Den Bogaert, Jan Wouters
    Abstract:

    In a Binaural Hearing aid system, output signals need to be generated for the left and the right ear. Using the Binaural multichannel Wiener filter (MWF), which exploits all microphone signals from both Hearing aids, a significant reduction of background noise can be achieved. However, due to power and bandwidth limitations of the Binaural link, it is typically not possible to transmit all microphone signals between the Hearing aids. To limit the amount of transmitted information, this paper presents reduced-bandwidth MWF-based noise reduction algorithms, where a filtered combination of the contralateral microphone signals is transmitted. A first scheme uses a signal-independent beamformer, whereas a second scheme uses the output of a monaural MWF on the contralateral microphone signals and a third scheme involves an iterative distributed MWF (DB-MWF) procedure. It is shown that in the case of a rank-1 speech correlation matrix, corresponding to a single speech source, the DB-MWF procedure converges to the Binaural MWF solution. Experimental results compare the noise reduction performance of the reduced-bandwidth algorithms with respect to the benchmark Binaural MWF. It is shown that the best performance of the reduced-bandwidth algorithms is obtained by the DB-MWF procedure and that the performance of the DB-MWF procedure approaches quite well the optimal performance of the Binaural MWF.

  • the effect of multimicrophone noise reduction systems on sound source localization by users of Binaural Hearing aids
    Journal of the Acoustical Society of America, 2008
    Co-Authors: Tim Van Den Bogaert, Simon Doclo, Jan Wouters, Marc Moonen
    Abstract:

    This paper evaluates the influence of three multimicrophone noise reduction algorithms on the ability to localize sound sources. Two recently developed noise reduction techniques for Binaural Hearing aids were evaluated, namely, the Binaural multichannel Wiener filter (MWF) and the Binaural multichannel Wiener filter with partial noise estimate (MWF-N), together with a dual-monaural adaptive directional microphone (ADM), which is a widely used noise reduction approach in commercial Hearing aids. The influence of the different algorithms on perceived sound source localization and their noise reduction performance was evaluated. It is shown that noise reduction algorithms can have a large influence on localization and that (a) the ADM only preserves localization in the forward direction over azimuths where limited or no noise reduction is obtained; (b) the MWF preserves localization of the target speech component but may distort localization of the noise component. The latter is dependent on signal-to-noise ratio and masking effects; (c) the MWF-N enables correct localization of both the speech and the noise components; (d) the statistical Wiener filter approach introduces a better combination of sound source localization and noise reduction performance than the ADM approach.

Marc Moonen - One of the best experts on this subject based on the ideXlab platform.

  • reduced bandwidth multi channel wiener filter based Binaural noise reduction and localization cue preservation in Binaural Hearing aids
    Signal Processing, 2014
    Co-Authors: Bram Cornelis, Marc Moonen, Jan Wouters
    Abstract:

    Binaural Hearing aids allow for a wireless exchange of microphone signals between a left and a right device. A significant noise reduction performance improvement can be achieved compared to a monaural configuration (a single device) or a bilateral configuration (in which the devices work independently). In addition, the Binaural localization cues, i.e. the Interaural Time Differences and Interaural Level Differences, can also be better preserved in a Binaural procedure. It was previously proven that a Binaural noise reduction procedure based on the Speech Distortion Weighted Multi-channel Wiener Filter (SDW-MWF) indeed preserves the speech localization cues, if all microphone signals can be exchanged. However, in practice, it may not be feasible to exchange all microphone signals between the devices, so that reduced-bandwidth SDW-MWF schemes (where only filtered combinations of microphone signals are exchanged) have to be utilized. This paper demonstrates that a straightforward reduced-bandwidth SDW-MWF scheme still preserves the speech ITD cues, but distorts the speech ILD cues, in a single speech source scenario. Novel reduced-bandwidth SDW-MWF schemes, which make use of a common spectral postfilter, are therefore introduced. Experiments in a reverberant environment demonstrate that the novel schemes reduce the ILD distortion, without severely degrading the noise reduction performance.

  • speech enhancement with multichannel wiener filter techniques in multimicrophone Binaural Hearing aids
    Journal of the Acoustical Society of America, 2009
    Co-Authors: Tim Van Den Bogaert, Simon Doclo, Jan Wouters, Marc Moonen
    Abstract:

    This paper evaluates speech enhancement in Binaural multimicrophone Hearing aids by noise reduction algorithms based on the multichannel Wiener filter (MWF) and the MWF with partial noise estimate (MWF-N). Both algorithms are specifically developed to combine noise reduction with the preservation of Binaural cues. Objective and perceptual evaluations were performed with different speech-in-multitalker-babble configurations in two different acoustic environments. The main conclusions are as follows: (a) A bilateral MWF with perfect voice activity detection equals or outperforms a bilateral adaptive directional microphone in terms of speech enhancement while preserving the Binaural cues of the speech component. (b) A significant gain in speech enhancement is found when transmitting one contralateral microphone signal to the MWF active at the ipsilateral Hearing aid. Adding a second contralateral microphone showed a significant improvement during the objective evaluations but not in the subset of scenarios t...

  • speech enhancement with multichannel wiener filter techniques in multimicrophone Binaural Hearing aids
    Journal of the Acoustical Society of America, 2009
    Co-Authors: Tim Van Den Bogaert, Simon Doclo, Jan Wouters, Marc Moonen
    Abstract:

    This paper evaluates speech enhancement in Binaural multimicrophone Hearing aids by noise reduction algorithms based on the multichannel Wiener filter (MWF) and the MWF with partial noise estimate (MWF-N). Both algorithms are specifically developed to combine noise reduction with the preservation of Binaural cues. Objective and perceptual evaluations were performed with different speech-in-multitalker-babble configurations in two different acoustic environments. The main conclusions are as follows: (a) A bilateral MWF with perfect voice activity detection equals or outperforms a bilateral adaptive directional microphone in terms of speech enhancement while preserving the Binaural cues of the speech component. (b) A significant gain in speech enhancement is found when transmitting one contralateral microphone signal to the MWF active at the ipsilateral Hearing aid. Adding a second contralateral microphone showed a significant improvement during the objective evaluations but not in the subset of scenarios tested during the perceptual evaluations. (c) Adding the partial noise estimate to the MWF, done to improve the spatial awareness of the Hearing aid user, reduces the amount of speech enhancement in a limited way. In some conditions the MWF-N even outperformed the MWF possibly due to an improved spatial release from masking.

  • reduced bandwidth and distributed mwf based noise reduction algorithms for Binaural Hearing aids
    IEEE Transactions on Audio Speech and Language Processing, 2009
    Co-Authors: Simon Doclo, Marc Moonen, Tim Van Den Bogaert, Jan Wouters
    Abstract:

    In a Binaural Hearing aid system, output signals need to be generated for the left and the right ear. Using the Binaural multichannel Wiener filter (MWF), which exploits all microphone signals from both Hearing aids, a significant reduction of background noise can be achieved. However, due to power and bandwidth limitations of the Binaural link, it is typically not possible to transmit all microphone signals between the Hearing aids. To limit the amount of transmitted information, this paper presents reduced-bandwidth MWF-based noise reduction algorithms, where a filtered combination of the contralateral microphone signals is transmitted. A first scheme uses a signal-independent beamformer, whereas a second scheme uses the output of a monaural MWF on the contralateral microphone signals and a third scheme involves an iterative distributed MWF (DB-MWF) procedure. It is shown that in the case of a rank-1 speech correlation matrix, corresponding to a single speech source, the DB-MWF procedure converges to the Binaural MWF solution. Experimental results compare the noise reduction performance of the reduced-bandwidth algorithms with respect to the benchmark Binaural MWF. It is shown that the best performance of the reduced-bandwidth algorithms is obtained by the DB-MWF procedure and that the performance of the DB-MWF procedure approaches quite well the optimal performance of the Binaural MWF.

  • the effect of multimicrophone noise reduction systems on sound source localization by users of Binaural Hearing aids
    Journal of the Acoustical Society of America, 2008
    Co-Authors: Tim Van Den Bogaert, Simon Doclo, Jan Wouters, Marc Moonen
    Abstract:

    This paper evaluates the influence of three multimicrophone noise reduction algorithms on the ability to localize sound sources. Two recently developed noise reduction techniques for Binaural Hearing aids were evaluated, namely, the Binaural multichannel Wiener filter (MWF) and the Binaural multichannel Wiener filter with partial noise estimate (MWF-N), together with a dual-monaural adaptive directional microphone (ADM), which is a widely used noise reduction approach in commercial Hearing aids. The influence of the different algorithms on perceived sound source localization and their noise reduction performance was evaluated. It is shown that noise reduction algorithms can have a large influence on localization and that (a) the ADM only preserves localization in the forward direction over azimuths where limited or no noise reduction is obtained; (b) the MWF preserves localization of the target speech component but may distort localization of the noise component. The latter is dependent on signal-to-noise ratio and masking effects; (c) the MWF-N enables correct localization of both the speech and the noise components; (d) the statistical Wiener filter approach introduces a better combination of sound source localization and noise reduction performance than the ADM approach.

Daniel Marquardt - One of the best experts on this subject based on the ideXlab platform.

  • comparison of two Binaural beamforming approaches for Hearing aids
    International Conference on Acoustics Speech and Signal Processing, 2017
    Co-Authors: Elior Hadad, Simon Doclo, Daniel Marquardt, Zhiquan Luo, Ivo Merks, Sharon Gannot, Tao Zhang
    Abstract:

    Beamforming algorithms in Binaural Hearing aids are crucial to improve speech understanding in background noise for Hearing impaired persons. In this study, we compare and evaluate the performance of two recently proposed minimum variance (MV) beamforming approaches for Binaural Hearing aids. The Binaural linearly constrained MV (BLCMV) beamformer applies linear constraints to maintain the target source and mitigate the interfering sources, taking into account the reverberant nature of sound propagation. The inequality constrained MV (ICMV) beamformer applies inequality constraints to maintain the target source and mitigate the interfering sources, utilizing estimates of the direction of arrivals (DOAs) of the target and interfering sources. The similarities and differences between these two approaches is discussed and the performance of both algorithms is evaluated using simulated data and using real-world recordings, particularly focusing on the robustness to estimation errors of the relative transfer functions (RTFs) and DOAs. The BLCMV achieves a good performance if the RTFs are accurately estimated while the ICMV shows a good robustness to DOA estimation errors.

  • Speech enhancement for multimicrophone Binaural Hearing aids aiming to preserve the spatial auditory scene
    EURASIP Journal on Advances in Signal Processing, 2016
    Co-Authors: Joachim Thiemann, Simon Doclo, Menno Müller, Daniel Marquardt, Steven Van De Par
    Abstract:

    Modern Binaural Hearing aids utilize multimicrophone speech enhancement algorithms to enhance signals in terms of signal-to-noise ratio, but they may distort the interaural cues that allow the user to localize sources, in particular, suppressed interfering sources or background noise. In this paper, we present a novel algorithm that enhances the target signal while aiming to maintain the correct spatial rendering of both the target signal as well as the background noise. We use a bimodal approach, where a signal-to-noise ratio (SNR) estimator controls a binary decision mask, switching between the output signals of a Binaural minimum variance distortionless response (MVDR) beamformer and scaled reference microphone signals. We show that the proposed selective Binaural beamformer (SBB) can enhance the target signal while maintaining the overall spatial rendering of the acoustic scene.

  • interaural coherence preservation in multi channel wiener filtering based noise reduction for Binaural Hearing aids
    IEEE Transactions on Audio Speech and Language Processing, 2015
    Co-Authors: Daniel Marquardt, Volker Hohmann, Simon Doclo
    Abstract:

    Besides noise reduction an important objective of Binaural speech enhancement algorithms is the preservation of the Binaural cues of all sound sources. To this end, an extension of the Binaural multi-channel Wiener filter (MWF), namely the MWF-ITF, has been proposed, which aims to preserve the Interaural Transfer Function (ITF) of the noise sources. However, the MWF-ITF is well-suited only for directional noise sources but not for, e.g., spatially isotropic noise, whose spatial characteristics cannot be properly described by the ITF but rather by the Interaural Coherence (IC). Hence, another extension of the Binaural MWF, namely the MWF-IC, has been recently proposed, which aims to preserve the IC of the noise component. Since for the MWF-IC a substantial tradeoff between noise reduction and IC preservation exists, in this paper we propose a perceptually constrained version of the MWF-IC, where the amount of IC preservation is controlled based on the IC discrimination ability of the human auditory system. In addition, a theoretical analysis of the Binaural cue preservation capabilities of the Binaural MWF and the MWF-ITF for spatially isotropic noise fields is provided. Several simulations in diffuse noise scenarios show that the perceptually constrained MWF-IC yields a controllable preservation of the IC without significantly degrading the output SNR compared to the Binaural MWF and the MWF-ITF. Furthermore, contrary to the Binaural MWF and MWF-ITF, the proposed algorithm retains the spatial separation between the output speech and noise components while the Binaural cues of the speech component are only slightly distorted, such that the Binaural Hearing advantage for speech intelligibility can still be exploited.

  • coherence preservation in multi channel wiener filtering based noise reduction for Binaural Hearing aids
    International Conference on Acoustics Speech and Signal Processing, 2013
    Co-Authors: Daniel Marquardt, Volker Hohmann, Simon Doclo
    Abstract:

    Besides noise reduction an important objective of Binaural speech enhancement algorithms is the preservation of the Binaural cues, i.e. the Interaural Level Difference and the Interaural Time Difference of all sound sources. Recently, extensions of the Binaural Multi-channel Wiener filter (MWF) have been presented, which aim to preserve the Binaural cues of the residual noise component. However, since these algorithms aim to preserve the Interaural Transfer Function (ITF), they are well-suited only for directional noise sources but not for, e.g. spatially isotropic noise, which can not be fully described by the ITF. In this paper, we present an extension of the Binaural MWF, aiming to preserve the Interaural Coherence of the residual noise component. Experimental results using spatially isotropic noise show that the proposed algorithm yields a good preservation of the Interaural Coherence without significantly degrading the output SNR compared to the Binaural MWF and the Binaural MWF with ITF preservation.

Volker Hohmann - One of the best experts on this subject based on the ideXlab platform.

  • interaural coherence preservation in multi channel wiener filtering based noise reduction for Binaural Hearing aids
    IEEE Transactions on Audio Speech and Language Processing, 2015
    Co-Authors: Daniel Marquardt, Volker Hohmann, Simon Doclo
    Abstract:

    Besides noise reduction an important objective of Binaural speech enhancement algorithms is the preservation of the Binaural cues of all sound sources. To this end, an extension of the Binaural multi-channel Wiener filter (MWF), namely the MWF-ITF, has been proposed, which aims to preserve the Interaural Transfer Function (ITF) of the noise sources. However, the MWF-ITF is well-suited only for directional noise sources but not for, e.g., spatially isotropic noise, whose spatial characteristics cannot be properly described by the ITF but rather by the Interaural Coherence (IC). Hence, another extension of the Binaural MWF, namely the MWF-IC, has been recently proposed, which aims to preserve the IC of the noise component. Since for the MWF-IC a substantial tradeoff between noise reduction and IC preservation exists, in this paper we propose a perceptually constrained version of the MWF-IC, where the amount of IC preservation is controlled based on the IC discrimination ability of the human auditory system. In addition, a theoretical analysis of the Binaural cue preservation capabilities of the Binaural MWF and the MWF-ITF for spatially isotropic noise fields is provided. Several simulations in diffuse noise scenarios show that the perceptually constrained MWF-IC yields a controllable preservation of the IC without significantly degrading the output SNR compared to the Binaural MWF and the MWF-ITF. Furthermore, contrary to the Binaural MWF and MWF-ITF, the proposed algorithm retains the spatial separation between the output speech and noise components while the Binaural cues of the speech component are only slightly distorted, such that the Binaural Hearing advantage for speech intelligibility can still be exploited.

  • coherence preservation in multi channel wiener filtering based noise reduction for Binaural Hearing aids
    International Conference on Acoustics Speech and Signal Processing, 2013
    Co-Authors: Daniel Marquardt, Volker Hohmann, Simon Doclo
    Abstract:

    Besides noise reduction an important objective of Binaural speech enhancement algorithms is the preservation of the Binaural cues, i.e. the Interaural Level Difference and the Interaural Time Difference of all sound sources. Recently, extensions of the Binaural Multi-channel Wiener filter (MWF) have been presented, which aim to preserve the Binaural cues of the residual noise component. However, since these algorithms aim to preserve the Interaural Transfer Function (ITF), they are well-suited only for directional noise sources but not for, e.g. spatially isotropic noise, which can not be fully described by the ITF. In this paper, we present an extension of the Binaural MWF, aiming to preserve the Interaural Coherence of the residual noise component. Experimental results using spatially isotropic noise show that the proposed algorithm yields a good preservation of the Interaural Coherence without significantly degrading the output SNR compared to the Binaural MWF and the Binaural MWF with ITF preservation.

  • real time multiband dynamic compression and noise reduction for Binaural Hearing aids
    Journal of Rehabilitation Research and Development, 1993
    Co-Authors: Birger Kollmeier, Jurgen Peissig, Volker Hohmann
    Abstract:

    A multi-signal-processor set-up is introduced that is used for real-time implementation of digital Hearing aid algorithms that operate on stereophonic (i.e., Binaural) input signals and perform signal processing in the frequency domain. A multiband dynamic compression algorithm was implemented which operates in 24 critical band filter channels, allows for interaction between frequency bands and stereo channels, and is fitted to the Hearing of the individual patient by a loudness scaling method. In addition, a Binaural noise reduction algorithm was implemented that amplifies sound emanating from the front and suppresses lateral noise sources as well as reverberation. These algorithms were optimized with respect to their processing parameters and by minimizing the processing artifacts. Different versions of the algorithms were tested in six listeners with sensorineural Hearing impairment using both subjective quality assessment methods and speech intelligibility measurements in different acoustical situations. For most subjects, linear frequency shaping was subjectively assessed to be negative, although it improved speech intelligibility in noise. Additional compression was assessed to be positive and did not deteriorate speech intelligibility as long as the processing parameters were fitted carefully. All noise reduction strategies employed here were subjectively assessed to be positive. Although the suppression of reverberation only slightly improved speech intelligibility, a combination of directional filtering and dereverberation provided a substantial improvement in speech intelligibility for most subjects and for a certain range of signal-to-noise ratios. The real-time implementation was very helpful in optimizing and testing the algorithms, and the overall results indicate that carefully designed and fitted Binaural Hearing aids might be very beneficial for a large number of patients.