Dr.-Ing. Florian Klein

Postdoctoral researcher and research assistant

Helmholtzbau, Room H 3520
+49 3677 69-1582
florian.klein@tu-ilmenau.de

Bibliography

Anzahl der Treffer: 47
Erstellt: Sun, 19 May 2024 20:42:53 +0200 in 0.0999 sec


Klein, Florian; Treybig, Lukas; Schneiderwind, Christian; Werner, Stephan; Sporer, Thomas
Just noticeable reverberation difference at varying loudness levels. - In: AES Europe 2023, (2023), S. 361-368

In order to successfully fuse virtual sound sources with the real acoustic environment, the acoustic properties of the real environment must be estimated and utilized for the synthesis of virtual sound sources. Often, just noticeable differences (JNDs) of room acoustic parameters are utilized to predict a good match between virtual and real acoustics. However, several studies in this domain have shown that existing JND values of room acoustic parameters are often not able to predict the perception of the listeners. This can have various reasons: Differences in first reflection patterns are barely measurable with classical acoustic parameters; Even if acoustic differences are above the JND, a plausible reproduction might still be possible; JNDs depend on various factors (such as sound signal, etc.) and existing studies do not cover all of them. The last factor is addressed in this research paper. A three-alternative forced (3AFC) choice test was conducted at four different loudness levels (75 dB(A), 65 dB(A), 55 dB(A), and 45 dB(A)) in a reverberation time range from 0.5 s to 0.8 s. A dependency of the loudness on the detectability of reverberation differences was found for the randomly interleaved presentation of loudness levels but not for sequential presentation. Individual hearing thresholds as well as expertise level significantly influence the JND of reverberation time.



Treybig, Lukas; Werner, Stephan; Klein, Florian; Amengual Garí, Sebastià V.
Robust reverberation time estimation for audio augmented reality applications. - In: AES Europe 2023, (2023), S. 47-55

The paper presents an alternative approach for estimating reverberation time from measurements in real rooms when the requirements of the standard DIN EN ISO 3382-1/2 for the characteristics of the sound source, receiver, and measurement positions cannot be met. The main goal is to minimize the variance of the calculated reverberation times when using a directional source and receiver, or source-receiver relative positions with very small distances. For this purpose, the energy decay curve for individual octave bands is sampled in time. The estimation starts 2 ms after the direct sound. This is followed by several estimates of the RT over a 20 dB drop, starting 1 dB later with each iteration. The best fit mean of these values gives the estimated reverberation time. A comparison with the standard reverberation time estimation shows a variance reduction of 10% to 30% for binaural room impulse responses (BRIRs). The proposed method finds its application in situations where measurements can only be made at a few positions in the room and/or only in a few areas of the room. Furthermore, the method should be better suitable for measurements with receivers located near or at the head of a person.



Stolz, Georg; Klein, Florian; Werner, Stephan; Treybig, Lukas; Bley, Andreas; Martin, Christian
Discussion of acoustic and perceptual optimization methods for measuring spatial room impulse responses with a mobile robotic platform. - In: 2023 Immersive and 3D Audio: from Architecture to Automotive (I3DA), (2023), insges. 7 S.

In the field of Auditory Augmented Reality (AAR), one aim is to provide a listening experience that is as close as possible to a real scenario. Measured Spatial Room Impulse Responses (SRIRs) describe the acoustics of a room and can serve as a reference for acoustic simulations or parametrization of room acoustics. In previous works, a measurement system for SRIRs using a mobile robotic platform was introduced. The system consists of a commercially available self-driving platform on which a microphone array is mounted, while the sound sources are distributed at fixed positions in the room. The system is able to conduct high spatial resolution measurements of SRIRs in a uniform grid. In applications where time is limited and/or the area to discover is large, however, a high-resolution measurement is not always feasible.Therefore, the goal of this contribution is to compare different approaches for optimizing the measurement grid. One approach is to use mathematical optimization on acoustic parameters derived from a small set of initial measurements to determine new measurement positions in a iterative manner. Another approach is to optimize the measurement grid in respect to human auditory perception, incorporating e.g. just-noticeable differences of distance and localization perception.The results show that both approaches can achieve significant reductions in the number of measurements required for a adequate acoustic spatial reproduction, with different trade-offs depending on the application scenario and the available prior information.



https://doi.org/10.1109/I3DA57090.2023.10289338
Klein, Florian; Surdu, Tatiana; Treybig, Lukas; Werner, Stephan
The ability to memorize acoustic features in a discrimination task. - In: Journal of the Audio Engineering Society, ISSN 0004-7554, Bd. 71 (2023), 5, S. 254-266

How humans perceive, recognize, 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 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, the authors present an exploratory study to evaluate the ability of listeners to recognize room acoustic features. The task of the listeners was to detect the reference room in a modified ABX double-blind stimulus test that featured a pre-defined playback order and a fixed time schedule. Furthermore, the authors explored distraction effects by employing additional nonacoustic interferences. The results show a significant decrease of the auditory memory capacity within 10 s, which is more pronounced when the listeners were distracted. However, the results suggest that auditory memory depends on what auditory cues are available.



https://doi.org/10.17743/jaes.2022.0073
Klein, Florian; Amengual Garí, Sebastià V.
The R3VIVAL dataset: repository of room responses and 360 videos of a variable acoustics lab. - In: IEEE ICASSP 2023 conference proceedings, (2023), insges. 5 S.

This paper presents a dataset of spatial room impulse responses (SRIRs) and 360˚ stereoscopic video captures of a variable acoustics laboratory. A total of 34 source positions are measured with 8 different acoustic panel configurations, resulting in a total of 272 SRIRs. The source positions are arranged in 30˚ increments at concentric circles of radius 1.5, 2, and 3 m measured with a directional studio monitor, as well as 4 extra positions at the room corners measured with an omnidirectional source. The receiver is a 7 channel open microphone array optimized for its use with the Spatial Decomposition Method (SDM). The 8 acoustic configurations are achieved by setting a subset of the panels to their absorptive configuration in 5 steps (0%, 25%, 50%, 75%, 100% of the panels), as well as 3 configurations in which entire walls are set to their absorptive configuration (right, right/back, right/back/left). Video captures of the laboratory and a second room are obtained using a 360˚ stereoscopic camera with a resolution of 4096 × 2160 pixels, covering the same source/receiver combinations. Furthermore, we present an acoustic analysis of both time-energy and spatio-temporal parameters showcasing the differences in the measured configurations. The dataset, together with spatial analysis and rendering scripts, is publicly released in a GitHub repository1.



https://doi.org/10.1109/ICASSP49357.2023.10097257
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; Seitelmann, 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
Richtiger Name des Verfassers: Florian Seitelmann

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.



https://doi.org/10.1109/MSP.2021.3110108
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.



https://doi.org/10.1177/23312165221092919
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.

https://doi.org/10.1109/I3DA48870.2021.9610835