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.
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.
Bridging distance with a collaborative telepresence robot for older adults - report on progress in the CO-HUMANICS project. - In: IEEE Xplore digital library, ISSN 2473-2001, (2023), S. 346-353
In an aging society, the social needs of older adults, such as regular interactions and independent living, are crucial for their quality of life. However, due to spatial separation from their family and friends, it is difficult to maintain social relationships. Our multidisciplinary project, CO-HUMANICS, aims to meet these needs, even over long distances, through the utilization of innovative technologies, including a robot-based system. This paper presents the first prototype of our system, designed to connect family members or friends virtually present through a mobile robot with an older adult. The system incorporates bi-directional video telephony, remote control capabilities, and enhanced visualization methods. A comparison is made with other state-of-the-art robotic approaches, focusing on remote control capabilities. We provide details about the hard- and software components, e.g., a projector-based pointing unit for collaborative telepresence to assist in everyday tasks. Our comprehensive scene representation is discussed, which utilizes 3D NDT maps, enabling advanced remote navigation features, such as autonomously driving to a specific object. Finally, insights about past and concepts for future evaluation are provided to assess the developed system.
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.
Acoustic inter- and intra-room similarity based on room acoustic parameters. - In: Engineering for a changing world, (2023), 5.2.136, S. 1-15
This paper shows various approaches for determining acoustic (dis-)similarity based on room acoustic parameter values derived from real measurements. The similarity is calculated across different room configurations and/or between different microphone-loudspeaker positions within the same room configuration. We compare supervised (LDA, Random Forrest) and unsupervised techniques (PCA, SPPA) and pre-selected visualizations in terms of their ability to exhibit inter- and intra-room (dis-)similarities. The data set generated comprises spatially high-resolution room impulse responses obtained from multiple source-receiver positions within a room configuration. The room acoustics are varied by introducing active walls and geometries accounting for specific room configurations. The results show that the separation of room configurations primarily relies on specific acoustic parameters, with the reverberation time playing an important role. Within a given room configuration, the acoustic parameters excluding the reverberation time mainly capture the orientation and distance between the source and receiver.
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.
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.
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.
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.
Digital media in intergenerational communication: status quo and future scenarios for the grandparent-grandchild relationship. - In: Universal access in the information society, ISSN 1615-5297, Bd. 0 (2022), 0, insges. 16 S.
Communication technologies play an important role in maintaining the grandparent-grandchild (GP-GC) relationship. Based on Media Richness Theory, this study investigates the frequency of use (RQ1) and perceived quality (RQ2) of established media as well as the potential use of selected innovative media (RQ3) in GP-GC relationships with a particular focus on digital media. A cross-sectional online survey and vignette experiment were conducted in February 2021 among N = 286 university students in Germany (mean age 23 years, 57% female) who reported on the direct and mediated communication with their grandparents. In addition to face-to-face interactions, non-digital and digital established media (such as telephone, texting, video conferencing) and innovative digital media, namely augmented reality (AR)-based and social robot-based communication technologies, were covered. Face-to-face and phone communication occurred most frequently in GP-GC relationships: 85% of participants reported them taking place at least a few times per year (RQ1). Non-digital established media were associated with higher perceived communication quality than digital established media (RQ2). Innovative digital media received less favorable quality evaluations than established media. Participants expressed doubts regarding the technology competence of their grandparents, but still met innovative media with high expectations regarding improved communication quality (RQ3). Richer media, such as video conferencing or AR, do not automatically lead to better perceived communication quality, while leaner media, such as letters or text messages, can provide rich communication experiences. More research is needed to fully understand and systematically improve the utility, usability, and joy of use of different digital communication technologies employed in GP-GC relationships.