Room acoustic analysis and BRIR matching based on room acoustic measurements. - In: AES International Conference on Audio for Virtual and Augmented Reality (AVAR 2022), (2022), S. 48-57
To achieve the goal of a perceptual fusion between the auralization of virtual audio objects in the room acoustics of a real listening room, an adequate adaptation of the virtual acoustics to the real room acoustics is necessary. The challenges are to describe the acoustics of different rooms by suitable parameters, to classify different rooms, and to evoke a similar auditory perception between acoustically similar rooms. An approach is presented to classify rooms based on measured BRIRs using statistical methods and to select best match BRIRs from the dataset to auralize audio objects in a new room. The results show that it is possible to separate rooms based on their room acoustic properties, that the separation also corresponds to a large extent to the perceptual distance between rooms, and that a selection of best match BRIRs is possible.
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, S. 1-20
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.
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.
Synthesis of binaural room impulse responses for different listening positions considering the source directivity. - In: 147th Audio Engineering Society Convention 2019, (2020), S. 377-385
Perceptual aspects in spatial audio processing. - In: Proceedings of the 23rd International Congress on Acoustics, (2019), S. 3354-3360
Spatial audio processing includes recording, modification and rendering of multichannel audio. In all these fields there is the choice of either a physical representation or of perceptual approaches trying to achieve a target perceived audio quality. Classical microphone techniques on one hand and wave field synthesis, higher order ambisonics or certain methods of binaural rendering for headphone reproduction on the other hand target a good physical representation of sound. As it is known today, especially in the case of sound reproduction a faithful physical recreation of the sound wave forms ("correct signal at the ear drums") is neither necessary nor does it allow a fully authentic or even plausible reproduction of sound. 20 years ago, MPEG-4 standardized different modes for perception based versus physics based reproduction (called "Perceptual approach to modify natural source" and "Acoustic properties for physical based audio rendering"). In spatial rendering today, more and more the perceptual approach is used in state of the art systems. We give some examples of such rendering. The same distinction of physics based versus psychoacoustics (including cognitive effects) based rendering is used today for room simulation or artificial reverb systems. Perceptual aspects are at the heart of audio signal processing today.
Plausible augmentation of auditory scenes using dynamic binaural synthesis for personalized auditory realities. - In: Science, technology, design, and implementation, (2018), S. 258-267
GO-LEM - Charakterisierung der auditorischen und auditorisch-visuellen Wahrnehmung des Menschen in Alltagsszenen. - In: Prävention von arbeitsbedingten Gesundheitsgefahren und Erkrankungen, (2017), S. 349-356
Evaluation of quality features of spatial audio signals in non-standardized rooms: two mixed method studies. - In: 140th Audio Engineering Society International Convention 2016, ISBN 978-1-5108-2570-3, (2016), S. 273-282
Comparison of evaluation methods for the quality assessment of audio signals. - In: Fortschritte der Akustik, ISBN 978-3-939296-10-2, (2016), S. 893-896
When evaluating audio signals not only the overall audio quality but also the underlaying quality parameters are of high interest. For this purpose relevant quality features, e.g., attribute and vocabulary lists, have been determined by several researchers. When evaluating the quality description of a set of audio signals with a few predefined quality features an appropriate evaluation design has to be found. This study presents a comparison of two evaluation paradigms. On one hand a single-stimulus-with-multiple-attributes method and on the other hand a multi-stimulus-with-single-attribute method were used for evaluation of the same stimuli and quality attributes.
Multidimensionality and context dependencies in quality evaluation of spatial audio signals. - In: Proceedings of the International Conference on Spatial Audio, ICSA 2014 in Erlangen, Germany, ISBN 978-3-9812830-4-4, (2014), S. 154-158
To authentically reproduce spatial audio signals it is important to know how these signals are perceived and evaluated by the subjects. The quality of the spatial audio signal can be described in overall quality, called the basic audio quality, or can be stripped down into several quality features. In the literature numerous experiments are conducted in which the multi-dimensionality of spatial audio signals is investigated. Results of these experiments are only reliable for the room in which they were performed. In this project the room is assumed as the contextual factor. The perception of the spatial audio signal is context dependent, this is especially important for loudspeaker reproduction. Goal of the research topic is to find consistent quality features and to assign them either to the technical signal or to the context. The second step is to define a standardised method to evaluate the quality features in different contexts and achieve reproducible and reliable results. A first approach is to evaluate quality features known from previous studies and to explore their correlation with the basic audio quality. This will be done in different reproduction rooms with different room characteristics with the use of a 5.0 loudspeaker setup. The project and the structure of the first listening test is described in this contribution.