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Kommunikationstechnisches Kolloquium am IKS
by Simone Sedgwick 30 Apr '25

30 Apr '25

Sehr geehrte Abonnenten des Kolloquium-Newsletters, gerne informieren wir Sie über den nächsten Termin unseres Kommunikationstechnischen Kolloquiums. *Freitag, 20. Oktober 2023* *Vortragender:* Kenan Linden *Zeit*: 12:00 Uhr *Ort*: hybrid - Hörsaal 4G und https://rwth.zoom.us/j/61215027648?pwd=MTJvayt5bkdka04raWZVempPZGE0Zz09 Meeting ID: 612 1502 7648 Passcode: 380386 *Bachelor-Vortrag:* */*Untersuchungen zur Interaktion von Feedforward- und Feedback-Regelung bei aktiver Störgeräuschkompensation in Kopfhörern*/* Für das Erstellen eines aktiven störgeräuschkompensierenden Systems (“ANC“) für Kopfhörer werden hauptsächlich die Ansätze eines Feedforward-System, eines Feedback-System oder einer Kombination der beiden, eines Hybrid-Systems verwendet. In dieser Arbeit werden Verfahren zum optimalen Entwurf eines Feedforward-Filters für die Integration in ein Hybrid-ANC-System vorgestellt und verglichen. Dabei werden weitere Variationen des Filters untersucht, mit dem Hintergrund, das Filter für realistische Anwen- dungen weiter zu optimieren. Um die Wichtigkeit bestimmter Frequenzen beim Erstellen des Filters hervorzuheben, wird eine Gewichtung eingeführt. Für das Entwerfen eines solchen Gewichts, wurde eine Messung durchgeführt, in welcher vier mögliche Eingangssignale zu einem Gewicht zusammengefasst wurden. Des Weiteren wurden zwei verschiedene variierende Feedback-Systeme und ihr Effekt auf das Hybrid-ANC-System genauer untersucht. Insgesamt wurden mit dem vorgestellten Hybrid-ANC-System eine deutliche Verbesserung in der Dämpfungen gegenüber dem verglichenen Feedforward-System erreicht. Mithilfe der eingeführten Gewichtung konnte das Filter eines Hybrid-Systems noch weiter für reale Anwen- dungen optimiert werden. Dabei stellte sich heraus, dass das Feedback-System komplett von einer geschickt gewählten Gewichtung kompensiert werden konnte, woraus sich entnehmen ließ, dass ein Hybrid-System auch unabhängig von einem Feedback-System ausgelegt werden kann, wenn die Gewichtung entsprechend gewählt wird. Zuletzt konnte beim Untersuchen des Feedback-Anteils für ein Hybrid-System gezeigt werden, dass das Hybrid-Filter, auch wenn es für den okklusions Effekt (“OE“) oder variante Feedback-Filter ausgelegt wird, deutlich bessere Ergebnisse verspricht als das Feedforward-System. Alle Interessierten sind herzlich eingeladen, eine Anmeldung ist nicht erforderlich. Allgemeine Informationen zum Kolloquium, sowie eine aktuelle Liste der Termine des Kommunikationstechnischen Kolloquiums finden Sie unter: http://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(a)iks.rwth-aachen.de https://www.iks.rwth-aachen.de/

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Communication Technology Colloquium at IKS
by Simone Sedgwick 09 Apr '25

09 Apr '25

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 -- 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(a)iks.rwth-aachen.de https://www.iks.rwth-aachen.de/

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Communication Technology Colloquium at IKS
by Anett Schindler 20 Nov '24

20 Nov '24

Dear subscribers of the colloquium newsletter, we are happy to inform you about the next date of our Communication Technology Colloquium. *Monday, November 25, 2024* *Speaker*: Eylül Ercandogu *Time:* 2:00 p.m. *Location*: hybrid - Lecture room 4G and https://rwth.zoom.us/j/61215027648?pwd=MTJvayt5bkdka04raWZVempPZGE0Zz09 Meeting-ID: 612 1502 7648 Passwort: 380386 *Master-Lecture: ** **Low-Complexity Noise Reduction for Hearables * In everyday life, noise interference significantly affects speech quality and intelligibility in various applications, such as hearing aids, earbuds, and mobile communication devices. These devices, known for their compactness and limited processing power, face challenges in implementing complex signal-processing algorithms. This work focuses on designing and evaluating efficient, real-time speech enhancement models tailored for low-complexity hearables. We adopted the Grouped Temporal Convolutional Recurrent Network (GTCRN), which reduces computational demands through efficient design elements. The real-time adaptation, RT-GTCRN, achieves competitive performance with minor quality trade-offs, making it well-suited for deployment on low-power devices. Additionally, we explored the axial self-attention mechanism to capture long-range dependencies efficiently. To improve speech quality, we incorporated advanced loss functions, including perceptual losses, which led to significant improvements in perceptual speech quality metrics. To enhance model generalization, we investigated data augmentation techniques and evaluated their impact across inter- and intra-corpus assessments. These data augmentation methods demonstrated promising improvements in handling diverse acoustic scenarios. Furthermore, knowledge distillation techniques were explored to enhance model efficiency by maintaining a small model while improving its performance. While the method demonstrated promise, further optimization could be beneficial to bridge the performance gap between the teacher and student models. The RT-GTCRN model was successfully implemented on the GAP9 processor, yielding promising results despite the observation of minor artifacts during implementation. These findings highlight potential areas for future refinement. 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 Best regards Anett Schindler Secretariat Institute of Communication Systems(IKS) Prof. Dr.-Ing. Peter Jax RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958(phone) +49 241 80 22254(fax) schindler(a)iks.rwth-aachen.de https://www.iks.rwth-aachen.de/

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Communication Technology Colloquium at IKS - Einladung Promotionsvortrag
by Anett Schindler 29 Oct '24

29 Oct '24

Dear subscribers of the colloquium newsletter, we are happy to inform you about the next date of our Communication Technology Colloquium. *Thursday, November 14, 2024* *Speaker*: Sebastian Nagel, M. Sc. *Topic*: Interactive Reproduction of Binaurally Recorded Signals *Time:* 11:30 a.m. *Location*: hybrid - Lecture room 4G *Online*: https://rwth.zoom.us/j/61215027648?pwd=MTJvayt5bkdka04raWZVempPZGE0Zz09 Meeting-ID: 612 1502 7648 Passwort: 380386 Abstract of the Dissertation *Interactive Reproduction of Binaurally Recorded Signals * by Sebastian Nagel, M.Sc. Motivation, Goal, and Task of this Dissertation The goal of acoustic augmented or virtual reality is to artificially invoke a realistic auditory impression in the listener. One technique to achieve this goal is /binaural reproduction/, which refers to the reproduction of certain audio signals at the two ears of the listener. The ear signals can be obtained by /binaural recording/ or /binaural rendering/, that is, by spatially sampling a real or virtual sound field with two microphones, one at each ear of a recording head. Such signals are referred to as /binaurally recorded signals/ in the following. For a moving listener to perceive sound sources as fixed in the environment, the reproduced signals need to match the listener’s movements. State-of-the-art methods for this /interactive binaural reproduction/ generate such signals based on denser spatial samplings of sound fields (i.e., more than two microphones), or they perform real-time binaural rendering. The goal of this thesis is to achieve interactive binaural reproduction based on binaurally recorded signals, that is, on two ear signals originally intended for non-interactive binaural reproduction for a non-moving listener. This is desirable for two major reasons. It makes binaural recordings usable for immersive playback. This potentially improves the user experience in applications such as telecommunications, or for consumer-generated content, where greater technical effort for recording may not be feasible. Furthermore, the resulting methods seamlessly interoperate with established technologies. Technically, binaurally recorded signals are ordinary stereo signals, and their spatial relationships are defined by human anatomy. This eliminates the coordination and standardization efforts that would be required to make the state-of-the-art methods widely usable. The task of this dissertation is to develop algorithms that interact with a complex biological system (the human auditory system). The ultimate evaluation criterion is the subjective quality of the listening experience to the human listener, which can only be assessed through listening experiments. Therefore, to validate the result, a listening experiment is presented at the end of the dissertation. Before that, algorithms are developed and evaluated on a theoretical basis. Derivations are based on signal models, and evaluations are based on the interpretation of signal properties, both of which are rooted in knowledge of human auditory perception. Major Scientific Contributions The model-based algorithms are developed in two steps. First, binaurally recorded signals with only coherent sound from a single sound source are regarded. The derived algorithms act as a time-variant filter to modify the spatial properties of the binaurally recorded signals. The filter is parameterized with the measured listener head motion and the source direction estimated from the recorded signals. This novel principle allows the listener to perceive the source in a stable position in the environment. It was first proposed by the author in [NJ18], and it has been patented [NJ23]. This dissertation provides analyses of different filter design methods and architectures. The subjective quality of the first algorithms is not suitable for signals which violate the model assumption of only direct sound, such as reverberant signals. Therefore, signals with a mix of coherent and incoherent sound are regarded in the second step. The derived algorithms perform a coherence-adaptive trade-off between the spatial modification of the coherent sound and the preservation of incoherent sound [NHJ20]. Their performance is theoretically limited by the limited ability of linear spatial filters to separate coherent and incoherent signal components [NJ21]. This dissertation provides a thorough analysis of the theoretical limitations. It also proposes perceptually motivated improvements to the filter structure that significantly extend the theoretical limits. Finally, this dissertation presents a listening experiment to validate the proposed method. Acoustic scenes with speech sources were binaurally recorded at the ears of human test subjects. A real-time prototype with head tracking provided interactive binaural reproduction of these recordings via headphones. Subjects were asked to distinguish, in an indirect comparison, the artificial binaural reproduction from reality (ground-truth signals emitted by the loudspeakers in the same room). Results show that this task was difficult even for expert listeners, indicating that the method provides a natural and plausible listening experience. Major Publications [NJ18] S. Nagel and P. Jax, “Dynamic Binaural Cue Adaptation,” in Proceedings of International Workshop on Acoustic Signal Enhancement (IWAENC), September 2018. [NHJ20] S. Nagel, D. Haupt, and P. Jax, “Coherence-Adaptive Binaural Cue Adaptation,” inProceedings of International Conference on Audio for Virtual and Augmented Reality (AVAR), August 2020. [NJ21] S. Nagel and P. Jax, “On the Use of Additional Microphones in Binaural Cue Adaptation,” in Proceedings of ITG Conference on Speech Communication, September 2021. [NJ23] S. Nagel and P. Jax, “Methods for obtaining and reproducing a binaural recording,” U.S. patent, US 11,546,703 B2, January 2023. 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 Best regards Anett Schindler *Anett Schindler* Institute of Communication Systems (IKS) RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958 schindler(a)iks.rwth-aachen.de https://www.iks.rwth-aachen.de/

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Communication Technology Colloquium at IKS
by Anett Schindler 08 Oct '24

08 Oct '24

Dear subscribers of the colloquium newsletter, we are happy to inform you about the next date of our Communication Technology Colloquium. *Monday, October 14, 2024* *Speaker*: Johannes Hahn *Time:* 14:00 pm *Location*: hybrid - Lecture room 4G and https://rwth.zoom.us/j/61215027648?pwd=MTJvayt5bkdka04raWZVempPZGE0Zz09 Meeting-ID: 612 1502 7648 Passwort: 380386 *Master-Lecture: ** * */*Identification of Time-Variant MIMO Systems using Acoustic Manifolds*/* Many applications in digital signal processing such as Acoustic Echo Cancellation (AEC) and adaptive Crosstalk Cancellation (CTC) rely on methods of Acoustic System Identification (ASI), which aims at determining the impulse responses between loudspeakers and microphones in a given acoustic enclosure. This task is particularly challenging if multiple inputs and outputs have to be considered, leading to a large number of parameters to be identified. The complexity increases further if the system and thus the parameters are time-varying. Moreover, such Multiple Inputs Multiple Outputs (MIMO) systems suffer from the non-uniqueness problem, which impairs the performance of established ASI methods. To overcome these challenges, recent developments focus on the incorporation of prior knowledge into the system identification. In this context, several approaches take advantage of the manifold hypothesis. It states that the Room Impulse Responses (RIRs) in a given MIMO scenario can be modeled by a low-dimensional representation lying on or close to a usually nonlinear manifold, which can be learned a-priori or estimated online. This thesis investigates a novel approach to the identification of time-variant MIMO systems which exploits the manifold hypothesis to greatly reduce the number of tracked parameters. A Variational Auto-Encoder (VAE) is trained to learn the manifold in terms of a low-dimensional coordinate representation. During ASI, only this representation is tracked, using an Extended Kalman Filter (EKF). As a result, less time-variant parameters have to be identified. Additionally, measurements are conducted using an artificial head and two loudspeakers to create a data set of real-world RIRs, and test sequences are recorded that facilitate the evaluation of ASI algorithms in a real-world scenario. In an extensive parameter study, the architecture and hyperparameters of the VAE are investigated and tuned. A validation of the proposed method in simulated scenarios as well as on the test recordings showcases its superiority in the identification of time-varying systems and its robustness towards the non-uniqueness problem in comparison to established ASI methods and related approaches built on the manifold hypothesis. 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 Anett Schindler Institute of Communication Systems(IKS) Prof. Dr.-Ing. Peter Jax RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany <https://www.google.com/maps/search/Muffeter+Weg+3a,+52074+Aachen,+Germany?e…> +49 241 80 26958(phone) +49 241 80 22254(fax) schindler <mailto:sedgwick@iks.rwth-aachen.de>@iks.rwth-aachen.de <mailto:sedgwick@iks.rwth-aachen.de> https://www.iks.rwth-aachen.de/

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Communication Technology Colloquium at IKS
by Anett Schindler 07 Oct '24

07 Oct '24

Dear subscribers of the colloquium newsletter, we are happy to inform you about the next date of our Communication Technology Colloquium. *Friday, October 11, 2024* *Speaker*: Lea Brehm *Time:* 11:00 am *Location*: hybrid - Lecture room 4G and https://rwth.zoom.us/j/61215027648?pwd=MTJvayt5bkdka04raWZVempPZGE0Zz09 Meeting-ID: 612 1502 7648 Passwort: 380386 *Bachelor-Lecture: ** * */*Evaluation of Sound Source Localization Algorithms with Recorded Binaural Signals*/* /The localization of binaural sound sources is essential for various modern applications. While most algorithms struggle with dynamic situations caused by the movement of the head, the movement invariant beamforming binaural direction of arrival estimator (MIBF DoA estimator) involves the information on head rotations. This algorithm applies the motion information to a target beamforming direction-of-arrival (DoA) estimator in order to identify the position of a sound source on the horizontal plane in dynamic situations./ /This thesis implements an extension of this algorithms to three dimensions, achieved by the usage of quaternions for the MIBF DoA estimator. We evaluate the algorithm based on simulations and data from an experimental set up. The results demonstrate that the algorithm identifies sound source positions in the three dimensional space correctly, especially during the movement of the head around multiple rotation axes. Furthermore, the utilization of head motions resolves problems caused by an ambiguous interaural time difference (ITD) and interaural level difference (ILD)./ / / 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 Anett Schindler Institute of Communication Systems(IKS) Prof. Dr.-Ing. Peter Jax RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany <https://www.google.com/maps/search/Muffeter+Weg+3a,+52074+Aachen,+Germany?e…> +49 241 80 26958(phone) +49 241 80 22254(fax) schindler <mailto:sedgwick@iks.rwth-aachen.de>@iks.rwth-aachen.de <mailto:sedgwick@iks.rwth-aachen.de> https://www.iks.rwth-aachen.de/

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Communication Technology Colloquium at IKS
by Anett Schindler 15 Aug '24

15 Aug '24

Dear subscribers of the colloquium newsletter, we are happy to inform you about the next date of our Communication Technology Colloquium. *Friday, August 23, 2024* *Speaker*: José Luis Conesa Pérez *Time:* 10.00 AM *Location*: hybrid - Lecture room 4G and https://rwth.zoom.us/j/61215027648?pwd=MTJvayt5bkdka04raWZVempPZGE0Zz09 Meeting-ID: 612 1502 7648 Passwort: 380386 *Master-Lecture: ** **Characterization of Vibration Transfer Paths for Earphones * Devices that seal the ear canal from the outside, such as insert earphones, create what is usually referred to as the Occlusion Effect. This effect generates a coloration of the signals, other than the ones produced by the device, that reach the eardrum. The consequences of this coloration are a reduction of the higher components of the spectrum of air-borne sounds, and an amplification of low-frequency sounds that reach the ear canal through bone vibration. In the efforts to cancel the Occlusion Effect, there is new research into adding vibration sensors to the earphones. These sensors can record the body-conducted sounds to counter the coloration introduced on the voice by the Occlusion Effect and enhance speech. Due to the closeness of the vibration sensor to the earphone, the Feedback Path has to be characterized in order to ensure stability of the system and avoid possible echoes. Therefore, this project’s objective is to study the feedback of the system. To this aim, a series of experiments have been conducted to test how the feedback from the loudspeaker is affected by different variables such as the tightness of the fit (how well the earphone seals the ear canal), the silicone tips used or changing the mass of the earphone. With these tests some insights into how the earphones work was gained, such as how the feedback can be reduced due to the ear canal not being perfectly sealed or by making the earphone heavier. The reduction caused by both previous examples is due to the loudspeaker having increased difficulties in moving the earphone due to energy escaping from the ear canal or a higher inertia of the earphone. In addition to these experiments, a measurement of a group of participants was conducted to inspect how the Feedback Path varies between individuals. To finalize the project, the basic mechanical behavior of the earphone when it reproduces inside of the ear canal was analyzed with the aim of creating a basic lumped element model that roughly describes its movements. This model proved to be only good as a first approximation, as it could not represent all the complexities of the vibration paths due to its simplicity. A system identification was also performed, with N4SID, on the lower parts of the spectrum of the Feedback Path to obtain the various poles and zeroes that represent the filter and observe their placement in the complex plane. 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 * * * * *Mit freundlichen Grüßen* *Anett Schindler* Institute of Communication Systems (IKS) Prof. Dr. -Ing. Peter Jax RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958 schindler(a)iks.rwth-aachen.de https://www.iks.rwth-aachen.de/

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Communication Technology Collquium at IKS
by Irina Esser 11 Oct '23

11 Oct '23

Dear subscribers of the Colloquium Newsletter, we are happy to inform you about the next date of our Communication Technology Colloquium. *Wednesday, 30. November 2022** **Speaker:* Frederick Pietschmann *Time*: 14:00 *Location:* Lecture room 4G and https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09 Meeting-ID: 979 0415 7921 Passwort: 481650 *Master-Lecture*: Perceptual Optimization and Evaluation of a Binaural Signal Modification Algorithm With individualized binaural signals, it is possible to reproduce auditory scenes such that the signal is perceived similar to the real scene. However, perceptual similarity is no longer achieved when the binaural signal doesn’t fully adapt to diﬀerent listeners and diﬀerent orientations of the listener’s head. To address these problems, a perceptually motivated algorithm referred to as the Binaural Cue Adaptation (BCA) system has been developed at the Institute of Communication Systems. The BCA system is capable of adding both interactivity and individualization to existing binaural signals, thereby achieving a higher degree of perceptual similarity to a corresponding real auditory scene. In this thesis, a perceptual optimization of the existing BCA system is conducted in that new approaches for some components of the algorithm are proposed, all parametrization options are identiﬁed and the overall best parametrization is chosen. To identify the best parametrization, both an isolated analysis of individual components is conducted and a perceptually motivated optimization procedure for a full system analysis is proposed and implemented. Finally, a perceptual evaluation based on the result of the perceptual optimization is realized. For this, two listening tests with a total number of 17 participants are conducted – one for a normal and one for a highly reverberant scenario. The results of these listening tests suggest that signals produced by the optimized BCA system achieve a high degree of perceptual plausibility for both reverberation scenarios, with an averaged 2AFC probability to detect a BCA-generated signal of 0.563 for the normal scenario and 0.604 for the highly reverberant scenario. 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 fount at: https://www.iks.rwth-aachen.de/aktuelles/kolloquium -- Irina Esser Institute of Communication Systems (IKS) RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958 (phone) esser(a)iks.rwth-aachen.de http://www.iks.rwth-aachen.de/

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Kommunikationstechnisches Kolloquium am IKS
by Irina Esser 16 Nov '22

16 Nov '22

Sehr geehrte Abonnenten des Kolloquium-Newsletters. gerne informieren wir Sie über den nächsten Termin unseres Kommunikationstechnischen Kolloquiums. *Mittwoch, 23. November 2022* *Vortragender: *Philipp Tigges *Zeit: *11:00 Uhr *O**rt*: hybrid - Hörsaal 4G und https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09 Meeting-ID: 979 0415 7921 Passwort: 481650 *Master-Vortrag*: Charakterisierung der Körperschallübertragung von Sprache für Hearables Körperschall ist ein wesentlicher Bestandteil bei der Wahrnehmung der eigenen Stimme. Das Übertragungsverhalten von Körperschall ist deutlich komplexer als bei Luftschall, da verschiedenste Gewebearten mit unterschiedlichen Eigenschaften durchlaufen werden. Da die Erzeugung von Sprachlauten ein vielschichtiger Prozess ist und die Bildung eines spezifischen Klangs auch mit dem Erzeugungsort zusammenhängt, liegt die Annahme eines phonemspezifischen Übertragungsverhaltens nahe. Ziel der Arbeit ist es, die Übertragung von Sprache über Körperschall zu charakterisieren, um die Eigenstimmwahrnehmung bei der Benutzung von Hearables zu verbessern. Für eine Auswahl an Phonemen wurde der Körperschall per Beschleunigungssensor und der Schall im inneren des Ohrkanal über ein Mikrofon gemessen. Die beiden Signale wurden dann auf lineare Zusammenhänge hin untersucht. Auf den Signalen wurden dann Filter ausgelegt, um aus dem Signal des Sensors das Signal im Ohrkanal zu schätzen und dann den Okklusionseffekt zu reduzieren. Es hat sich gezeigt, dass zwischen dem Signal des Beschleunigungssensors und dem Signal im Ohrkanal ein linearer Zusammenhang gefunden werden kann. Das Übertragungsverhalten der verschiedenen Phoneme unterscheidet sich, jedoch sind die Unterschiede klein genug, so dass sich Filter zur Okklusionsreduktion auch auf andere Laute anwenden lassen. Auch für gesprochenen Text können Filter gefunden werden, die den Okklusionseffekt effektiv reduzieren können. Zusätzlich wurden auch einige Geräusche, die sich auch über Körperschall ausbreiten, analysiert. Hier war es deutlich schwerer lineare Zusammenhänge zu finden. Im weiteren Verlauf wurden dann die Rahmenbedingungen realistischer gestaltet, indem der Sekundärpfad mit einbezogen wurde. Außerdem fordern reale Anwendungen kausalen Filtern. Diese zeigten sich ähnlich performant, wie ihre akausalen Äquivalente, jedoch mit starken Überhöhungen vor allem zu hohen Frequenzen, da sie nah an der Kausalitätsgrenze arbeiten müssen. Im letzten Teil der Analyse konnten erste Einblicke in die Frage, ob die erstellten Filter eine ausgeprägte Abhängigkeit von der jeweiligen Person haben, gewonnen werden. Diese Abhängigkeit hat sich insbesondere bei den auf einzelnen Phonemen ausgelegten Filtern gezeigt. Alle Interessierten sind herzlich eingeladen, eine Anmeldung ist nicht erforderlich. Allgemeine Informationen zum Kolloquium sowie eine aktuelle Liste der Termine des Kommunikationstechnischen Kolloquiums finden Sie unter: http://www.iks.rwth-aachen.de/aktuelles/kolloquium -- Irina Esser Institute of Communication Systems (IKS) RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958 (phone) ronkartz(a)iks.rwth-aachen.de http://www.iks.rwth-aachen.de/

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Kommunikationstechnisches Kolloquium am IKS
by Irina Esser 10 Nov '22

10 Nov '22

Sehr geehrte Abonnenten des Kolloquium-Newsletters, gerne informieren wir Sie über den nächsten Termin unseres Kommunikationstechnischen Kolloquiums. *Mittwoch, 16. November 2022* *Vortragende:* Jana Lorenz *Zeit*: 09:00 Uhr *Ort*: hybrid - Hörsaal 4G und https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09 Meeting-ID: 979 0415 7921 Passwort: 481650 *Bachelor-Vortrag:* Vergleich adaptiver Algorithmen für die aktive Störgeräuschkompensation bei Kopfhörern in komplexen Schallfeldern Lärmbelästigung ist ein alltägliches Problem. Es gibt viele Ansätze diese zu reduzieren. Kopfhörer mit aktiver Störgeräuschunterdrückung (ANC, engl. Active Noise Cancellation) sind einer davon. Sie kompensieren vor allem tieffrequente Geräusche, welche passiv nur unzureichend gedämpft werden können. Dabei hat das Störgeräusch einen großen Einfluss auf die aktiven Kompensationsmöglichkeiten. Dieses kann sich in realen Umgebungen bezogen auf seine Einfallsrichtung oder seine statistischen Eigenschaften verändern und somit die aktive Störgeräuschunterdrückung erschweren. Daher sind adaptive Feedforward-Algorithmen von großer Bedeutung, da diese sich kontinuierlich an das sich verändernde Störgeräusch anpassen können. So werden in dieser Arbeit zwei ANC-Filterstrukturen, der Filtered-x Least Mean Square Algorithmus (FxLMS) und der Adaptive Linear Combiner (ALC), betrachtet. Es wird untersucht, wie sich die feste adaptiv gewichtete Parallelfilterstruktur des ALC, verglichen zum FxLMS-Algorithmus, auf das Konvergenzverhalten und die aktive Dämpfung auswirkt. In dieser Arbeit werden beide Algorithmen anhand von Schallfeldern verschiedener Komplexität verglichen. Es werden ruhende, sich räumlich bewegende und komplexere Schallfelder verwendet. Dabei erreicht die ALC-Filterstruktur, verglichen zum FxLMS-Algorithmus, auf Kosten einer geringeren maximal möglichen aktiven Dämpfung, eine schnellere Konvergenzzeit. Alle Interessierten sind herzlich eingeladen, eine Anmeldung ist nicht erforderlich. Allgemeine Informationen zum Kolloquium, sowie eine aktuelle Liste der Termine des Kommunikationstechnischen Kolloquiums finden Sie unter: http://www.iks.rwth-aachen.de/aktuelles/kolloquium -- Irina Esser Institute of Communication Systems (IKS) RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958 (phone) esser(a)iks.rwth-aachen.de http://www.iks.rwth-aachen.de/

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