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BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260703T110000
DTEND;TZID=Europe/Berlin:20260703T120000
DTSTAMP:20260816T224913
CREATED:20260619T092833Z
LAST-MODIFIED:20260619T092833Z
UID:4003-1783076400-1783080000@blog.rwth-aachen.de
SUMMARY:Haoyue Liu: Uncertainties in Acoustic Surface Impedance Measurement
DESCRIPTION:Accurate determination of acoustic ground impedance is essential for predicting sound propagation over outdoor surfaces. However\, the measurement process is affected by uncertainties arising from the experimental setup\, particularly from variations in source and receiver positioning. The objective of this thesis is to investigate how geometric uncertainties propagate through impedance measurement procedures and influence the resulting acoustic quantities. \nAn experiment is conducted to characterize geometric positioning uncertainties under practical measurement conditions. The resulting probability distributions are used as input for the Monte Carlo (MC) uncertainty propagation framework. The uncertainty analysis is performed using a simulation based on the analytical Weyl–Van der Pol sound propagation model. Two impedance deduction approaches from the standard ANSI/ASA S1.18-2018\, namely the template method and the direct method\, are investigated\, with the template method serving as the main focus. The propagation of geometric uncertainty is analyzed from the measurement setup to the complex pressure ratio\, level difference\, impedance\, and reflection factor. Boundary analysis is used to evaluate worst-case scenarios\, and the influence of repeated measurements is investigated through a grouping approach based on multiple geometric realizations. \nThe results show that uncertainty arising solely from geometric setup variations is relatively small but strongly frequency-dependent. In general\, the uncertainties of both the real and imaginary parts of the impedance are larger at low frequencies than at high frequencies. The resulting frequency-averaged standard uncertainty in the reflection factor remains well below 1 dB. \nMelden Sie sich hier an um Einladungen zu den Kolloquium-Vorträgen per E-Mail zu erhalten.\nRegister here to receive the invitations to colloquium talks via e-mail. \nZoom-Meeting-ID: 643 7384 8607\nPasswort: 2020000
URL:https://blog.rwth-aachen.de/akustik/event/haoyue-liu-uncertainties-in-acoustic-surface-impedance-measurement/
LOCATION:IHTA Seminarraum (60 Persons) and Zoom-Meeting (Hybrid)\, Kopernikusstr. 5\, Aachen\, 52074\, Deutschland
CATEGORIES:Verteidigung Masterarbeit
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260708T110000
DTEND;TZID=Europe/Berlin:20260708T120000
DTSTAMP:20260816T224913
CREATED:20260630T114058Z
LAST-MODIFIED:20260630T114058Z
UID:4027-1783508400-1783512000@blog.rwth-aachen.de
SUMMARY:Maximilian Semmler: Integrationskosten audiovisueller Sprache im Kurzzeitgedächtnis
DESCRIPTION:Audiovisuelle Sprache verbessert im Allgemeinen\, aber insbesondere unter ungünstigen Hörbedingungen\, die Sprachverständlichkeit\, indem sie ergänzende visuelle Informationen liefert. Es bleibt jedoch unklar\, ob sich diese Wahrnehmungsvorteile auch in einer verbesserten Arbeitsgedächtnisleistung niederschlagen oder ob die Integration von auditiver und visueller Sprache zusätzliche kognitive Kosten mit sich bringt. Bisherige Studien konnten die potenziellen Integrationskosten nicht ermitteln\, da sie oft von den Verständlichkeitsvorteilen überlagert wurden. Die vorliegende Studie untersuchte den Einfluss der audiovisuellen Sprache auf das Arbeitsgedächtnis unter Kontrolle der Sprachverständlichkeit. Um wahrnehmungsbezogenen Effekte zu minimieren\, wurden individuelle Signal-Rausch-Verhältnisse für beide Modalitäten bestimmt\, um vordefinierte Verständlichkeitsniveaus von 80% und 95% für beide Darstellungsmodalitäten zu erreichen. Die Teilnehmer absolvierten eine Serial Recall Aufgabe\, bei der Sequenzen aus neun gesprochenen Buchstaben entweder auditiv oder audiovisuell präsentiert wurden. Darüber hinaus wurde die subjektive Anstrengung anhand eines Fragebogens erfasst. Bei einem Verständlichkeitsgrad von 80% war die Genauigkeit des Serial Recall bei audiovisueller Sprache signifikant geringer als bei rein auditiver Sprache\, während bei einem Verständlichkeitsgrad von 95% kein vergleichbarer Unterschied festgestellt wurde. Obwohl die Interaktion zwischen Verständlichkeit und Präsentationsmodalität statistisch nicht signifikant war\, deutet das beobachtete Muster darauf hin\, dass der Einfluss audiovisueller Sprache auf das Arbeitsgedächtnis möglicherweise von der Verständlichkeit abhängt. Im Gegensatz dazu wurde die subjektive Anstrengung in erster Linie von der Verständlichkeit und weniger von der Präsentationsmodalität beeinflusst. Diese Ergebnisse zeigen\, dass audiovisuelle Sprache nicht zu einer verbesserten Leistung des Arbeitsgedächtnisses führt. Durch die Kontrolle der Verständlichkeit über alle Präsentationsmodalitäten hinweg liefert die vorliegende Studie Belege dafür\, dass audiovisuelle Sprache zusätzliche kognitive Kosten verursachen kann\, die bei Gedächtnisaufgaben unter schwierigen Hörbedingungen auftreten. Der Vortrag wird auf Deutsch gehalten. \nEN: The Cost of Audiovisual Speech Integration in Short-Term Memory \nAudiovisual speech generally improves speech intelligibility by providing complementary visual information\, particularly under adverse listening conditions. However\, it remains unclear whether these perceptual benefits also translate into improved working memory performance or whether the integration of auditory and visual speech cues imposes additional cognitive demands. Previous studies have been unable to distinguish the potential costs of integration because these costs were overshadowed by the benefits in terms of intelligibility. The present study investigated the influence of audiovisual speech presentation on working memory while controlling for speech intelligibility. To minimize perceptual confounds\, individual signal-to-noise ratios were determined separately for auditory-only and audiovisual speech\, yielding predefined intelligibility levels of 80% and 95% for both presentation modalities. Participants completed a serial recall task in which sequences of nine spoken letters were presented either auditorily or audiovisually. In addition\, subjective effort was assessed using a questionnaire. Recall accuracy was significantly lower for audiovisual speech than for auditory-only speech at the 80% intelligibility level\, whereas no comparable difference was observed at 95% intelligibility. Although the interaction between intelligibility and presentation modality was not statistically significant\, the observed pattern suggests that the influence of audiovisual speech on working memory may depend on intelligibility. In contrast\, subjective effort was primarily affected by intelligibility rather than presentation modality. These findings demonstrate that audiovisual speech does not result in improved working memory performance. By controlling for intelligibility across presentation modalities\, the present study provides evidence that audiovisual speech may impose additional cognitive demands that become apparent during memory tasks under challenging listening conditions. The talk will be given in German \nMelden Sie sich hier an um Einladungen zu den Kolloquium-Vorträgen per E-Mail zu erhalten.\nRegister here to receive the invitations to colloquium talks via e-mail. \nZoom-Meeting-ID: 643 7384 8607\nPasswort: 2020000
URL:https://blog.rwth-aachen.de/akustik/event/maximilian-semmler-integrationskosten-audiovisueller-sprache-im-kurzzeitgedaechtnis/
LOCATION:IHTA Seminarraum (60 Persons) and Zoom-Meeting (Hybrid)\, Kopernikusstr. 5\, Aachen\, 52074\, Deutschland
CATEGORIES:Verteidigung Masterarbeit
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260710T110000
DTEND;TZID=Europe/Berlin:20260710T120000
DTSTAMP:20260816T224913
CREATED:20260507T075338Z
LAST-MODIFIED:20260507T075338Z
UID:3974-1783681200-1783684800@blog.rwth-aachen.de
SUMMARY:Cosima A. Ermert: Simulating complex listening scenarios in audiovisual virtual reality - The impact of audiovisual cues\, spatial noise\, and room acoustics on listening performance
DESCRIPTION:Real-life listening is inherently complex. Everyday environments rarely provide clear speech in anechoic conditions. Instead\, they often contain multiple partially masking sound sources\, varying spatial configurations\, and room acoustic reflections. Moreover\, listeners typically rely not only on auditory\, but also on visual cues\, such as lip-movement\, gestures\, gaze\, and embodiment. Thus\, listening performance in such complex environments cannot be predicted from acoustic conditions alone. Recent technological advances enable the simulation of complex auditory and visual environments (e.g.\, through virtual reality). Still\, many studies employ simplified environments when examining listening performance\, which may result in findings that do not generalise to real-life. \nThe primary objective of this thesis was to assess how systematic increments in auditory and audiovisual complexity affect listening performance\, conceptualised in terms of working memory and listening effort. Seven experiments reported in five publications were conducted that gradually increased complexity in controlled steps. The experiments introduced spatial audio reproduction and spatial target and background position changes\, varied the semantic content and temporal structure of background noise\, examined the influence of display device and audiovisual incongruences in virtual environments with embodied conversational agents and finally investigated the influence of room acoustic conditions in a simulated audiovisually complex environment. Further\, throughout the thesis\, the complexity of the task was increased from the classical serial recall task with isolated digits as target items towards a joint analysis of memory and listening effort by employing the heard-text-recall task in a dual-task design. \nAcross studies\, multiple acoustic manipulations\, such as the content of the task-irrelevant stimuli and reverberation\, showed clear effects on listening performance\, whereas the examined variations of visual cues (i.e.\, display device and audio-visual incongruences) had limited impact. The findings suggest a task-dependent relevance of audiovisual cues and highlight the interdependency of environment\, target source\, task\, and receiver. \nConclusively\, the thesis proposes a framework of audiovisual complexity that extends existing acoustic models by explicitly incorporating visual\, receiver-related\, and technical dimensions. In addition\, a conceptual distinction between descriptive and generative approaches to complexity is introduced\, which might aid more differentiated discussions and interpretations of future findings. In this context\, this thesis highlights that current simulation-based approaches and experimental paradigms may not capture real-life listening to a sufficient degree\, and argues for a more holistic perspective on complex listening scenarios that incorporates behaviour- and experience-based dependent variables. \nTogether\, these contributions aim to support the design and interpretation of future listening experiments in complex audiovisual environments and to move towards models that are better suited to predicting everyday listening. This way\, ultimately\, listening experience can be improved particularly for vulnerable listener groups\, such as people with hearing impairment. \nMelden Sie sich hier an um Einladungen zu den Kolloquium-Vorträgen per E-Mail zu erhalten.\nRegister here to receive the invitations to colloquium talks via e-mail. \nZoom-Meeting-ID: 627 6065 6043\nPasswort: Akustik
URL:https://blog.rwth-aachen.de/akustik/event/cosima-a-ermert-simulating-complex-listening-scenarios-in-audiovisual-virtual-reality-the-impact-of-audiovisual-cues-spatial-noise-and-room-acoustics-on-listening-performance/
LOCATION:IHTA Seminarraum (60 Persons) and Zoom-Meeting (Hybrid)\, Kopernikusstr. 5\, Aachen\, 52074\, Deutschland
CATEGORIES:Verteidigung Dissertation
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20260721T110000
DTEND;TZID=Europe/Berlin:20260721T120000
DTSTAMP:20260816T224913
CREATED:20260714T144319Z
LAST-MODIFIED:20260714T144319Z
UID:4069-1784631600-1784635200@blog.rwth-aachen.de
SUMMARY:Anne Heimes: Acoustic Bidirectional Surface Scattering - Analysis\, Validation and Application
DESCRIPTION:Geometrical acoustics simulations are an essential tool for predicting sound propagation in rooms and urban environments. A key requirement for physically accurate simulations is an appropriate representation of surface scattering to capture wave-related phenomena at surfaces. In current acoustic practice\, surface reflection is commonly described by decomposing reflected sound energy into specular and scattered components\, with the scattered part modeled using Lambert’s cosine law. The amount of scattered energy relative to the total reflected energy is quantified by a scattering coefficient\, which is most often determined as a random-incidence value under diffuse-field conditions according to ISO 17497-1. These coefficients typically assume sufficiently large surfaces\, such that scattering behavior can be considered independent of sample size. \nDespite its widespread use\, this conventional framework has fundamental limitations. Random-incidence averaging fails to capture scattering behavior that depends on the incidence direction. In addition\, Lambertian scattering assumes an isotropic redistribution of scattered energy\, independent of the incidence direction and the actual reflection pattern of the surface geometry. For many surfaces\, particularly periodic or pseudo-periodic geometries\, the scattering behavior depends strongly on surface geometry\, incidence direction\, and acoustic wavelength\, producing distinct outgoing scattering directions. These simplifications are especially problematic for surfaces such as acoustic diffusers\, building facades\, or retroreflective elements and lead to systematic inaccuracies in geometrical acoustic simulations. \nDirectional scattering coefficients provide additional information by accounting for the dependence on incidence direction and can be obtained with free-field methods such as the correlation method. However\, these coefficients are rarely used directly in simulations and are often averaged over incidence directions to determine random-incidence values. As a result\, a representation that captures both incidence and outgoing directions in a physically meaningful and practically applicable manner is still missing. \nTo overcome these limitations\, this dissertation introduces the bidirectional scattering coefficient (BSC) as an energy-based metric that explicitly accounts for incidence direction\, scattering direction\, and frequency dependence. Like the scattering coefficient\, the BSC quantifies the fraction of reflected acoustic energy redistributed into a specific outgoing direction relative to the total reflected energy. Determining BSCs requires extending the correlation method to compute complete bidirectional scattering coefficients from numerical simulations and physical measurements on finite-sized samples. The approach is validated using a well-documented sinusoidal test surface\, allowing direct comparison with analytical solutions for infinite surfaces and previously reported random-incidence scattering coefficients. \nMelden Sie sich hier an um Einladungen zu den Kolloquium-Vorträgen per E-Mail zu erhalten.\nRegister here to receive the invitations to colloquium talks via e-mail. \nZoom-Meeting-ID: 643 7384 8607\nPasswort: 2020000
URL:https://blog.rwth-aachen.de/akustik/event/anne-heimes-acoustic-bidirectional-surface-scattering-analysis-validation-and-application/
LOCATION:IHTA Seminarraum (60 Persons) and Zoom-Meeting (Hybrid)\, Kopernikusstr. 5\, Aachen\, 52074\, Deutschland
CATEGORIES:Verteidigung Dissertation
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