Dipl.-Ing. M.Sc. Annika Neidhardt

Wissenschaftliche Mitarbeiterin und Doktorandin

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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.

Neidhardt, Annika; Zerlik, Anna Maria
The availability of a hidden real reference affects the plausibility of position-dynamic auditory AR. - In: Frontiers in virtual reality, ISSN 2673-4192, Bd. 2 (2021), 678875, S. 1-17

This study examines the plausibility of Auditory Augmented Reality (AAR) realized with position-dynamic binaural synthesis over headphones. An established method to evaluate the plausibility of AAR asks participants to decide whether they are listening to the virtual or real version of the sound object. To date, this method has only been used to evaluate AAR systems for seated listeners. The AAR realization examined in this study instead allows listeners to turn to arbitrary directions and walk towards, past, and away from a real loudspeaker that reproduced sound only virtually. The experiment was conducted in two parts. In the first part, the subjects were asked whether they are listening to the real or the virtual version, not knowing that it was always the virtual version. In the second part, the real versions of the scenes where the loudspeaker actually reproduced sound were added. Two different source positions, three different test stimuli, and two different sound levels were considered. Seventeen volunteers, including five experts, participated. In the first part, none of the participants noticed that the virtual reproduction was active throughout the different test scenes. The inexperienced listeners tended to accept the virtual reproduction as real, while experts distributed their answers approximately equally. In the second part, experts could identify the virtual version quite reliably. For inexperienced listeners, the individual results varied enormously. Since the presence of the headphones influences the perception of the real sound field, this shadowing effect had to be considered in the creation of the virtual sound source as well. This requirement still limits test methods considering the real version in its ecological validity. Although the results indicate that the availability of a hidden real reference leads to a more critical evaluation, it is crucial to be aware that the presence of the headphones slightly distorts the reference. This issue seems more vital to the plausibility estimates achieved with this evaluation method than the increased freedom in motion.

Schneiderwind, Christian; Neidhardt, Annika; Meyer, Dominik
Comparing the effect of different open headphone models on the perception of a real sound source. - In: 150th Audio Engineering Society Convention 2021, (2021), S. 389-398

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.

Neidhardt, Annika; Reif, Boris
Minimum BRIR grid resolution for interactive position changes in dynamic binaural synthesis. - In: 148th Audio Engineering Society International Convention 2020, (2020), S. 660-669

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.

Neidhardt, Annika; Schneiderwind, Christian
Physical and perceptual differences of selected approaches to realize an echolocation scenario in room acoustical auralizations. - In: Proceedings of the International Symposium on Room Acoustics, (2019), S. 237

Schneiderwind, Christian; Neidhardt, Annika
Perceptual differences of position dependent room acoustics in a small conference room. - In: Proceedings of the International Symposium on Room Acoustics, (2019), S. 499-506

Remaggi, Luca; Kim, Hansung; Neidhardt, Annika; Hilton, Adrian; Jackson, Philip J. B.
Perceived quality and spatial impression of room reverberation in VR reproduction from measured images and acoustics. - In: Proceedings of the 23rd International Congress on Acoustics, (2019), S. 3361-3368