Dear subscribers of the colloquium newsletter,
we are happy to inform you about the next date of our Communication Technology Colloquium.
*Wednesday, January 18, 2022* *Speaker*: Konstantin Wehmeyer *Time:* 2:00 p.m. *Location*: hybrid - Lecture room 4G and https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09
Meeting-ID: 979 0415 7921 Passwort: 481650
*Bachelor-Lecture: ***Deep Learning-Based Speech Synthesis as Post-Processing of a Noise Reduction
/Audio and speech signals are often disturbed by noise signals in frequency- and/or time-limited parts. To attenuate or remove these distortions, several methods, including deep learning- based approaches, are known. Often, however, only the magnitude spectrum is processed and the phase spectrum is taken over unchanged due to its comparatively lower relevance. Consequently, the noisy phase is reused when synthesizing the waveform from the processed magnitude spectrum. Therefore, distortions in the magnitude spectrum can be reduced, but not in the phase spectrum which inevitably leads to a deterioration in speech quality and intelligibility./
/This thesis presents methods that allow a reconstruction of the phase spectrum of speech signals based on noise-reduced magnitude spectra. At the Institute of Communication Systems at RWTH Aachen University a phase reconstruction algorithm was developed and this algorithm has already been evaluated in a previous study for the case of smoothed magnitude spectra. It was shown that the deep neural network (DNN) used can benefit from targeted training on the smoothed magnitude spectra even without further modification of the network structures. However, even slight smearing of the magnitude spectra already leads to a significant loss in performance compared to the use of perfect magnitude spectra. In this work, therefore, the DNNs used are optimized for the case of noise-reduced magnitude spectra. // /
/Several deep learning-based models are introduced and compared with each other and with the models already developed. Their properties and aspects such as causality are addressed. Moreover, a new loss function and assessment measure specifically designed to estimate and assess the phase spectrum of speech signals is developed and tested. In order to be able to evaluate the results as independently as possible of a specific type of noise reduction, ideal masks are developed, used, and discussed. /
All interested parties are cordially invited, registration is not required.
General information on the colloquium, as well as a current list of dates of the Communication Technology Colloquium can be found at: https://www.iks.rwth-aachen.de/aktuelles/kolloquium
Dear subscribers of the colloquium newsletter,
we are happy to inform you about the next date of our Communication Technology Colloquium.
*Thursday, March 9, 2023* *Speaker*: Maximilian Tillmann *Time:* 2:00 p.m. *Location*: hybrid - Lecture room 4G and https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09
Meeting-ID: 979 0415 7921 Passwort: 481650
*Master-Lecture: *Investigations on Autoencoder Models for Online System Identification
/Speech communication devices are indispensable in our daily work and personal lives. Using them in hands free mode can create an echo signal, which, if no action is taken, would disturb the speaker. However, the echo signal can be predicted, when the impulse response between loudspeaker and microphone is known. For this task, system identification algorithms exist, such as the Least-Mean-Square (LMS) algorithm, the Normalized-Least-Mean-Square (NLMS) algorithm, and the Kalman filter.They work well in general, but face difficulties when confronted with high correlation input signals, high noise levels, or rapidly changing impulse responses over time./ / This thesis aims to explore whether prior knowledge about the impulse response can improve system identification.The key approach is to utilize the manifold hypothesis, which has shown promising results in previous works in mapping acoustic room impulse responses to a lower dimensional subspace. These approaches require training data of impulse responses. This thesis investigates how well affine subspace models can represent impulse response with a limited number of subspace components compared to the same number of components in the time domain. One well known way to find an optimal affine subspace is by Principal- Component-Analysis (PCA). It is shown that the affine subspace model can have the same achievable system mismatch with significantly less number of subspace components, when the loudspeaker and the microphone are constrained in their positions./ / The manifoldLMSalgorithm, the manifoldNLMSalgorithm and the manifold Kalman filter are proposed in this thesis, which can utilise general non linear manifolds for the acoustic echo compensation task. For the manifoldLMSandNLMSalgorithm in the case of white noise excitation and an affine manifold, the expected convergence speed and the expected steady state system mismatch are derived theoretically and are shown to accurately describe the algorithms behaviour in simulations.For scenarios with constrained loudspeaker and microphone positions it is shown that the manifoldNLMSalgorithm significantly outperforms the time domainNLMSalgorithm.The manifold Kalman filter is compared to the time domain Kalman filter and another subspace approach from literature. /
All interested parties are cordially invited, registration is not required.
General information on the colloquium, as well as a current list of dates of the Communication Technology Colloquium can be found at: https://www.iks.rwth-aachen.de/aktuelles/kolloquium
Dear subscribers of the colloquium newsletter,
I am sorry, but I have to inform about the changing appointment:
*Wednesday, March 8, 2023* *Speaker*: Maximilian Tillmann *Time:* 11:00 a.m. *Location*: hybrid - Lecture room 4G and https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09
Meeting-ID: 979 0415 7921 Passwort: 481650
*Master-Lecture: *Investigations on Autoencoder Models for Online System Identification
see below...
//
Simone Sedgwick Secretariat Institute of Communication Systems(IKS) Prof. Dr.-Ing. Peter Jax RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26956(phone) +49 241 80 22254(fax) sedgwick@iks.rwth-aachen.de https://www.iks.rwth-aachen.de/
Am 27.02.2023 um 15:04 schrieb Simone Sedgwick:
Dear subscribers of the colloquium newsletter,
we are happy to inform you about the next date of our Communication Technology Colloquium.
*Thursday, March 9, 2023* *Speaker*: Maximilian Tillmann *Time:* 2:00 p.m. *Location*: hybrid - Lecture room 4G and https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09
Meeting-ID: 979 0415 7921 Passwort: 481650
*Master-Lecture: *Investigations on Autoencoder Models for Online System Identification
/Speech communication devices are indispensable in our daily work and personal lives. Using them in hands free mode can create an echo signal, which, if no action is taken, would disturb the speaker. However, the echo signal can be predicted, when the impulse response between loudspeaker and microphone is known. For this task, system identification algorithms exist, such as the Least-Mean-Square (LMS) algorithm, the Normalized-Least-Mean-Square (NLMS) algorithm, and the Kalman filter.They work well in general, but face difficulties when confronted with high correlation input signals, high noise levels, or rapidly changing impulse responses over time./ / This thesis aims to explore whether prior knowledge about the impulse response can improve system identification.The key approach is to utilize the manifold hypothesis, which has shown promising results in previous works in mapping acoustic room impulse responses to a lower dimensional subspace. These approaches require training data of impulse responses. This thesis investigates how well affine subspace models can represent impulse response with a limited number of subspace components compared to the same number of components in the time domain. One well known way to find an optimal affine subspace is by Principal- Component-Analysis (PCA). It is shown that the affine subspace model can have the same achievable system mismatch with significantly less number of subspace components, when the loudspeaker and the microphone are constrained in their positions./ / The manifoldLMSalgorithm, the manifoldNLMSalgorithm and the manifold Kalman filter are proposed in this thesis, which can utilise general non linear manifolds for the acoustic echo compensation task. For the manifoldLMSandNLMSalgorithm in the case of white noise excitation and an affine manifold, the expected convergence speed and the expected steady state system mismatch are derived theoretically and are shown to accurately describe the algorithms behaviour in simulations.For scenarios with constrained loudspeaker and microphone positions it is shown that the manifoldNLMSalgorithm significantly outperforms the time domainNLMSalgorithm.The manifold Kalman filter is compared to the time domain Kalman filter and another subspace approach from literature. /
All interested parties are cordially invited, registration is not required.
General information on the colloquium, as well as a current list of dates of the Communication Technology Colloquium can be found at: https://www.iks.rwth-aachen.de/aktuelles/kolloquium -- Simone Sedgwick Institute of Communication Systems(IKS) Prof. Dr.-Ing. Peter Jax RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26956(phone) +49 241 80 22254(fax) sedgwick@iks.rwth-aachen.de https://www.iks.rwth-aachen.de/
Dear subscribers of the colloquium newsletter,
we are happy to inform you about the next date of our Communication Technology Colloquium.
*Friday, April 28, 2023* *Speaker*: Helena Janning *Time:* 11:00 a.m. *Location*: hybrid - Lecture room 4G and https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09
Meeting-ID: 979 0415 7921 Passwort: 481650
*Bachelor-Lecture: **
Direction-of-Arrival Estimation in Headphones using Subspace Methods* *Einfallsrichtungsschätzung bei Kopfhörern mittels Unterraummethoden*
In order to estimate the direction of arrival of a sound source, different algorithms exist which vary in accuracy, robustness, computational complexity and memory requirements.
In the thesis, a modified Steered-Response Power (SRP) algorithm with a Minimum Variance Distortionless Response (MVDR) beamformer is presented, whose computational complexity and memory requirements are reduced compared to the original algorithm. For this purpose, the auto- and cross-energy spectral density of the device-related transfer functions are approximated using a principal component analysis.
It could be shown that the maximum complexity saving is 97,23% and the memory requirement can be reduced by 91,72%. Depending on the requirements for the estimation quality, further savings can be achieved.
All interested parties are cordially invited, registration is not required.
General information on the colloquium, as well as a current list of dates of the Communication Technology Colloquium can be found at: https://www.iks.rwth-aachen.de/aktuelles/kolloquium
Simone Sedgwick Secretariat Institute of Communication Systems(IKS) Prof. Dr.-Ing. Peter Jax RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26956(phone) +49 241 80 22254(fax) sedgwick@iks.rwth-aachen.de https://www.iks.rwth-aachen.de/
kommunikationstechnik-kolloquium@lists.rwth-aachen.de
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Simone Sedgwick