August 2024 - Kommunikationstechnik-Kolloquium

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 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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