Dr.-Ing. Florian Klein

Postdoktorand und wissenschaftlicher Mitarbeiter

Helmholtzbau, Raum H 3520
+49 3677 69-1582


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Erstellt: Sat, 25 Mar 2023 23:13:12 +0100 in 0.0435 sec

Klein, Florian; Surdu, Tatiana; Aretz, Arthur; Birth, Kilian; Edelmann, Niklas; Seitelman, Florian; Ziener, Christian; Werner, Stephan; Sporer, Thomas
A dataset of measured spatial room impulse responses in different rooms including visualization. - In: AES Europe Spring 2022, (2022), S. 621-625

In this contribution, an open-source dataset of captured spatial room impulse responses (SRIRs) is presented. The data was collected in different enclosed spaces at the Technische Universität Ilmenau using an open self-build microphone array design following the spatial decomposition method (SDM) guidelines. The included rooms were selected based on their distinctive acoustical properties resulting from their general build and furnishing as required by their utility. Three different classes of spaces can be distinguished, including seminar rooms, offices, and classrooms. For each considered space different source-receiver positions were recorded, including 360? images for each condition. The dataset can be utilized for various augmented or virtual reality applications, using either a loudspeaker or headphone-based reproduction alongside the appropriate head-related transfer function sets. The complete database, including the measured impulse responses as well as the corresponding images, is publicly available.

Klein, Florian; Surdu, Tatiana; Treybig, Lukas; Werner, Stephan; Aretz, Arthur; Birth, Kilian; Edelmann, Niklas; Seitelman, Florian; Ziener, Christian; Sporer, Thomas
Auditory room identification in a memory task. - In: AES International Conference on Audio for Virtual and Augmented Reality (AVAR 2022), (2022), S. 132-141

How we perceive and remember room acoustics is of particular interest in the domain of spatial audio. For the creation of virtual or augmented acoustic environments, a room acoustic impression needs to be created which matches the expectations of certain room classes or a specific room. These expectations are based on the auditory memory of the acoustic room impression. In this paper, we present an exploratory study to evaluate the ability of listeners to remember specific rooms. The task of the listeners was to detect the reference room in a modified ABX double-blind stimulus test which featured a pre-defined playback order and a fixed time schedule. Furthermore, we explored distraction effects by employing additional non-acoustic interferences. The results show a significant decrease of the auditory memory capacity within ten seconds, which is more pronounced when the listeners were distracted. However, the results suggest that auditory memory depends on what auditory cues are available.

Gupta, Rishabh; He, Jianjun; Ranjan, Rishabh; Gan, Woon Seng; Klein, Florian; Schneiderwind, Christian; Neidhardt, Annika; Brandenburg, Karlheinz; Välimäki, Vesa
Augmented/mixed reality audio for hearables: sensing, control, and rendering. - In: IEEE signal processing magazine, ISSN 1558-0792, Bd. 39 (2022), 3, S. 63-89

Augmented or mixed reality (AR/MR) is emerging as one of the key technologies in the future of computing. Audio cues are critical for maintaining a high degree of realism, social connection, and spatial awareness for various AR/MR applications, such as education and training, gaming, remote work, and virtual social gatherings to transport the user to an alternate world called the metaverse. Motivated by a wide variety of AR/MR listening experiences delivered over hearables, this article systematically reviews the integration of fundamental and advanced signal processing techniques for AR/MR audio to equip researchers and engineers in the signal processing community for the next wave of AR/MR.

Neidhardt, Annika; Schneiderwind, Christian; Klein, Florian
Perceptual matching of room acoustics for auditory augmented reality in small rooms - literature review and theoretical framework. - In: Trends in hearing, ISSN 2331-2165, Bd. 26 (2022), S. 1-22

For the realization of auditory augmented reality (AAR), it is important that the room acoustical properties of the virtual elements are perceived in agreement with the acoustics of the actual environment. This perceptual matching of room acoustics is the subject reviewed in this paper. Realizations of AAR that fulfill the listeners? expectations were achieved based on pre-characterization of the room acoustics, for example, by measuring acoustic impulse responses or creating detailed room models for acoustic simulations. For future applications, the goal is to realize an online adaptation in (close to) real-time. Perfect physical matching is hard to achieve with these practical constraints. For this reason, an understanding of the essential psychoacoustic cues is of interest and will help to explore options for simplifications. This paper reviews a broad selection of previous studies and derives a theoretical framework to examine possibilities for psychoacoustical optimization of room acoustical matching.

Gari, Sebastia V. Amengual; Hassager, Henrik G.; Klein, Florian; Arend, Johannes M.; Robinson, Philip W.
Towards determining thresholds for room divergence: a pilot study on perceived externalization. - In: 2021 Immersive and 3D Audio: from Architecture to Automotive (I3DA), (2021), insges. 7 S.

Klein, Florian; Gari, Sebastia V. Amengual; Arend, Johannes M.; Robinson, Philip W.
Towards determining thresholds for room divergence: a pilot study on detection thresholds. - In: 2021 Immersive and 3D Audio: from Architecture to Automotive (I3DA), (2021), insges. 7 S.

In binaural rendering, the room divergence effect refers to the decrease in perceived externalization due to a mismatch between the room acoustics of the virtual sounds and those of the listening space. However, it is currently unknown which specific acoustic differences cause this effect. In this work, we present a pilot study to determine detection thresholds between sound sources recorded under different acoustic conditions in a variable acoustics room. These results are intended to predict situations where divergence effects can be expected. The participants had to perform a triangle test where they could listen to three sound sources placed at different positions in the room. The test design was motivated by the fact that sound sources are not placed at the same position in real acoustic scenes. One sound source was recorded under different acoustic conditions than the other two, and the task for the participant was to detect the differing source. The test was conducted in the measured room using 3 DoF binaural reproduction and using a virtual reality (VR) headset to display a visual 360 capture of the room enabling the subjects to see the positions of the sources in the room. Detection rates are signal-dependent and increase with differences in reverberation time (RT). For the most critical signal in the test (castanets), an RT difference of 8% was detectable, while the difference was 15% across all conditions. Furthermore, we discuss the influence of sound source distance and absorption configuration (symmetric or asymmetric) on detection thresholds.

Klein, Florian;
Auditive Adaptationsprozesse im Kontext räumlicher Audiowiedergabesysteme. - Ilmenau : Universitätsbibliothek, 2021. - 1 Online-Ressource (ii, 145 Seiten)
Technische Universität Ilmenau, Dissertation 2021

Das Ziel technischer Weiterentwicklungen im Bereich der Unterhaltungselektronik ist die Optimierung der Benutzererfahrung durch die stetige Verbesserung der audiovisuellen Wiedergabe. Durch die Fortschritte im Bereich virtueller und augmentierter Realitäten wurde das Ziel einer realitätsnahen Wiedergabe immer greifbarer. Werden die Sinnesreize so perfekt imitiert, dass es dem Nutzer nicht mehr möglich ist künstlich erzeugte Schallquellen von Realen zu unterscheiden, ist die Rede von einer auditiven Illusion. In erster Linie sind die damit verbundenen Herausforderungen technischer Natur. Allerdings führt eine exakte Reproduktion der Ohrsignale nicht zwangsläufig zur gleichen Wahrnehmung wie in der entsprechenden realen Situation. Neben sinnesübergreifenden Wechselwirkungen, liegt dies daran, dass unsere Wahrnehmung stark von unseren Erwartungen und Erfahrungen abhängt. Diese Erwartungen können sich je nach vorheriger Schallexposition ändern. In Bezug auf das räumliche Hören bedeutet dies, dass Menschen wahrscheinlich lernen können wie räumliche Signale und ihre Merkmale zu interpretieren sind. Solche Mechanismen und ihre Auswirkungen auf die wahrgenommene Qualität von räumlichen Audiowiedergabesystemen ist der Gegenstand dieser Arbeit. In Wahrnehmungsstudien wurde das Erlernen von Lokalisationsmerkmalen untersucht sowie Adaptationsprozesse bei der raumakustischen Wahrnehmung näher beleuchtet. Es wird betrachtet mit welchen Qualitätsdefiziten zu rechnen ist, wenn die Ohrsignale nicht korrekt reproduziert werden und wie sich die Qualitätsbeurteilung abhängig vom Training ändert. Die Ergebnisse deuten darauf hin, dass Lern- und Adaptationsprozesse ein ausschlaggebender Faktor für das Zustandekommen einer auditiven Illusion ist. Die Arbeit diskutiert sowohl die praktische Relevanz dieser Effekte als auch die zugrundeliegenden Lern- und Adaptationsvorgänge.

Arend, Johannes M.; Garí, Sebastià V. Amengual; Schissler, Carl; Klein, Florian; Robinson, Philip W.
Six-degrees-of-freedom parametric spatial audio based on one monaural room impulse response. - In: Journal of the Audio Engineering Society, ISSN 0004-7554, Bd. 69 (2021), 7/8, S. 557-575

Parametric spatial audio rendering is a popular approach for low computing capacity applications, such as augmented reality systems. However most methods rely on spatial room impulse responses (SRIR) for sound field rendering with 3 degrees of freedom (DoF), i.e., for arbitrary head orientations of the listener, and often require multiple SRIRs for 6-DoF rendering, i.e., when additionally considering listener translations. This paper presents a method for parametric spatial audio rendering with 6 DoF based on one monaural room impulse response (RIR). The scalable and perceptually motivated encoding results in a parametric description of the spatial sound field for any listener's head orientation or position in space. These parameters form the basis for the binaural room impulse responses (BRIR) synthesis algorithm presented in this paper. The physical evaluation revealed good performance, with differences to reference measurements at most tested positions in a room below the just-noticeable differences of various acoustic parameters. The paper further describes the implementation of a 6-DoF realtime virtual acoustic environment (VAE) using the synthesized BRIRs. A pilot study assessing the plausibility of the 6-DoF VAE showed that the system can provide a plausible binaural reproduction, but it also revealed challenges of 6-DoF rendering requiring further research.

Werner, Stephan; Klein, Florian; Neidhardt, Annika; Sloma, Ulrike; Schneiderwind, Christian; Brandenburg, Karlheinz
Creation of auditory augmented reality using a position-dynamic binaural synthesis system - technical components, psychoacoustic needs, and perceptual evaluation. - In: Applied Sciences, ISSN 2076-3417, Bd. 11 (2021), 3, 1150, insges. 20 S.

For a spatial audio reproduction in the context of augmented reality, a position-dynamic binaural synthesis system can be used to synthesize the ear signals for a moving listener. The goal is the fusion of the auditory perception of the virtual audio objects with the real listening environment. Such a system has several components, each of which help to enable a plausible auditory simulation. For each possible position of the listener in the room, a set of binaural room impulse responses (BRIRs) congruent with the expected auditory environment is required to avoid room divergence effects. Adequate and efficient approaches are methods to synthesize new BRIRs using very few measurements of the listening room. The required spatial resolution of the BRIR positions can be estimated by spatial auditory perception thresholds. Retrieving and processing the tracking data of the listener’s head-pose and position as well as convolving BRIRs with an audio signal needs to be done in real-time. This contribution presents work done by the authors including several technical components of such a system in detail. It shows how the single components are affected by psychoacoustics. Furthermore, the paper also discusses the perceptive effect by means of listening tests demonstrating the appropriateness of the approaches.

Brandenburg, Karlheinz; Klein, Florian; Neidhardt, Annika; Sloma, Ulrike; Werner, Stephan
Creating auditory illusions with binaural technology. - In: The technology of binaural understanding, (2020), S. 623-663

It is pointed out that beyond reproducing the physically correct sound pressure at the eardrums, more effects play a significant role in the quality of the auditory illusion. In some cases, these can dominate perception and even overcome physical deviations. Perceptual effects like the room-divergence effect, additional visual influences, personalization, pose and position tracking as well as adaptation processes are discussed. These effects are described individually, and the interconnections between them are highlighted. With the results from experiments performed by the authors, the perceptual effects can be quantified. Furthermore, concepts are proposed to optimize reproduction systems with regard to those effects. One example could be a system that adapts to varying listening situations as well as individual listening habits, experience and preference.