The use of non-intrusive virtual environments is gaining more and more importance but was focused mainly on addressing the visual sense. However, the human perception consists not only of visual input and thus it would be worthwhile to create multi-modal and interactive virtual environments. This thesis describes the techniques required to include the acoustic component into a virtual environment and furthermore the implementation of a software system, which takes advantage of these techniques to create complex acoustical scenes in real time. The system is based on the binaural technology. It features spatially distributed sound sources which are utilized to create an environment that is as authentic as possible. This comprises a description of the source, including its relevant angle-, distance- and time- dependent radiation, the sound distribution in the virtual scene (room acoustics), the perception-related consideration of all sound field components, as well as the exact reproduction of the artificial sound at the ears of the user. The focus of this thesis is put on the reproduction technology. In this context, an approach for dynamic crosstalk cancellation is presented, which enables a loudspeaker-based reproduction. The required filters are processed in real time on the basis of the position data and measured transfer functions of the outer ear. Furthermore the integration of this spatial audio system into a five-sided Virtual Reality display system is described and evaluated.
In this work the importance of individualization in binaural technique is investigated. The results extend the present knowledge on the efficient measurement of individual head-related transfer functions (HRTFs) and highlight the importance of individual equalization filters in binaural reproduction, using both loudspeakers and headphones. Moreover, an integrated framework for the calculation of such equalization filters is presented. An innovative measurement setup was developed to allow the fast acquisition of individual HRTFs. The hardware was designed to be compatible with the range extrapolation technique. An individual HRTF dataset with 4000 directions can be measured in less than 6 minutes with this new setup. A framework was presented that integrates causality constraints to the regularized frequency domain calculation of crosstalk cancellation (CTC) filter. This framework also addresses the switching of active loudspeakers applying a weighted filter calculation method. A sound localization test showed that individualized CTC systems provide performance similar to that of binaural listening while nonindividualized CTC systems provide a significantly lower localization performance. Finally, a robust individual headphone equalization method was proposed. Perceptual tests showed that, in all but one of the tested situations, no audible differences between the original sound source and its binaural auditory display could be perceived.
The current popular and scientific interest in virtual environments has provided a new impetus for investigating binaural and spatial hearing. However, the many intriguing phenomena of spatial hearing have long made it an exciting area of scientific inquiry. Psychophysical and physiological investigations of spatial hearing seem to be converging on common explanations of underlying mechanisms. These understandings have in turn been incorporated into sophisticated yet mathematically tractable models of binaural interaction. Thus, binaural and spatial hearing is one of the few areas in which professionals are soon likely to find adequate physiological explanations of complex psychological phenomena that can be reasonably and usefully approximated by mathematical and physical models. This volume grew out of the Conference on Binaural and Spatial Hearing, a four-day event held at Wright-Patterson Air Force Base in response to rapid developments in binaural and spatial hearing research and technology. Meant to be more than just a proceedings, it presents chapters that are longer than typical proceedings papers and contain considerably more review material, including extensive bibliographies in many cases. Arranged into topical sections, the chapters represent major thrusts in the recent literature. The authors of the first chapter in each section have been encouraged to take a broad perspective and review the current state of literature. Subsequent chapters in each section tend to be somewhat more narrowly focused, and often emphasize the authors' own work. Thus, each section provides overview, background, and current research on a particular topic. This book is significant in that it reviews the important work during the past 10 to 15 years, and provides greater breadth and depth than most of the previous works.
This book explores the nature and importance of sound in virtual reality (VR). Approaching the subject from a holistic perspective, the book delivers an emergent framework of VR sound. This framework brings together numerous elements that collectively determine the nature of sound in VR; from various aspects of VR technology, to the physiological and psychological complexities of the user, to the wider technological, historical and sociocultural issues. Garner asks, amongst other things: what is the meaning of sound? How have fictional visions of VR shaped our expectations for present technology? How can VR sound hope to evoke the desired responses for such an infinitely heterogeneous user base? This book if for those with an interest in sound and VR, who wish to learn more about the great complexities of the subject and discover the contemporary issues from which future VR will surely advance.
Immersive Sound: The Art and Science of Binaural and Multi-Channel Audio provides a comprehensive guide to multi-channel sound. With contributions from leading recording engineers, researchers, and industry experts, Immersive Sound includes an in-depth description of the physics and psychoacoustics of spatial audio as well as practical applications. Chapters include the history of 3D sound, binaural reproduction over headphones and loudspeakers, stereo, surround sound, height channels, object-based audio, soundfield (ambisonics), wavefield synthesis, and multi-channel mixing techniques. Knowledge of the development, theory, and practice of spatial and multi-channel sound is essential to those advancing the research and applications in the rapidly evolving fields of 3D sound recording, augmented and virtual reality, gaming, film sound, music production, and post-production.
Virtual reality has the potential to simulate a variety of real-world scenarios for training- and entertainment-purposes, as it has the ability to induce a sense of 0́−presence0́+: the illusion that the user is physically transported to another location and is really 0́−there0́+. VR and VR-technologies have seen a recent market resurgence due to the arrival of affordable, mass-market VR-display systems, such as the Oculus Rift, HTC Vive, PlayStation VR, Samsung GearVR, and Google Cardboard. However, the use of tactile feedback to convey information about the virtual environment is often lacking in VR applications. This study addresses this lack by proposing the use of binaural audio in VR to induce illusory tactile feedback. This is done by examining the literature on intersensory illusions as well as the relationship between audio and tactile feedback to inform the design of a software prototype that is able to induce the desired feedback. This prototype is used to test the viability of such an approach to induce illusory tactile feedback and to investigate the nature of this feedback. The software prototype is used to collect data from users regarding their experiences of this type of feedback and its underlying causes. Data collection is done through observation, questionnaires, interviews, and focus groups and the results indicate that the use of binaural audio in VR can be used to effectively induce an illusory sense of tactile feedback in the absence of real-world feedback. This study contributes insights regarding the nature of illusory sensations in VR, focusing on touch-sensations. This study also provides consolidated definitions of immersion and presence as well as a consolidated list of aspects of immersion, both of which are used to detail the relationship between immersion, presence, and illusory tactile feedback. Findings provide insight into the relationship between the design of audio in VR and its ability to alter perception in the tactile modality. Findings also provide insight into aspects of VR, such as presence and believability, and their relationship to perception across various sensory modalities.
Sound, devoid of meaning, would not matter to us. It is the information sound conveys that helps the brain to understand its environment. Sound and its underlying meaning are always associated with time and space. There is no sound without spatial properties, and the brain always organizes this information within a temporal–spatial framework. This book is devoted to understanding the importance of meaning for spatial and related further aspects of hearing, including cross-modal inference. People, when exposed to acoustic stimuli, do not react directly to what they hear but rather to what they hear means to them. This semiotic maxim may not always apply, for instance, when the reactions are reflexive. But, where it does apply, it poses a major challenge to the builders of models of the auditory system. Take, for example, an auditory model that is meant to be implemented on a robotic agent for autonomous search-&-rescue actions. Or think of a system that can perform judgments on the sound quality of multimedia-reproduction systems. It becomes immediately clear that such a system needs • Cognitive capabilities, including substantial inherent knowledge • The ability to integrate information across different sensory modalities To realize these functions, the auditory system provides a pair of sensory organs, the two ears, and the means to perform adequate preprocessing of the signals provided by the ears. This is realized in the subcortical parts of the auditory system. In the title of a prior book, the term Binaural Listening is used to indicate a focus on sub-cortical functions. Psychoacoustics and auditory signal processing contribute substantially to this area. The preprocessed signals are then forwarded to the cortical parts of the auditory system where, among other things, recognition, classification, localization, scene analysis, assignment of meaning, quality assessment, and action planning take place. Also, information from different sensory modalities is integrated at this level. Between sub-cortical and cortical regions of the auditory system, numerous feedback loops exist that ultimately support the high complexity and plasticity of the auditory system. The current book concentrates on these cognitive functions. Instead of processing signals, processing symbols is now the predominant modeling task. Substantial contributions to the field draw upon the knowledge acquired by cognitive psychology. The keyword Binaural Understanding in the book title characterizes this shift. Both books, The Technology of Binaural Listening and the current one, have been stimulated and supported by AABBA, an open research group devoted to the development and application of models of binaural hearing. The current book is dedicated to technologies that help explain, facilitate, apply, and support various aspects of binaural understanding. It is organized into five parts, each containing three to six chapters in order to provide a comprehensive overview of this emerging area. Each chapter was thoroughly reviewed by at least two anonymous, external experts. The first part deals with the psychophysical and physiological effects of Forming and Interpreting Aural Objects as well as the underlying models. The fundamental concepts of reflexive and reflective auditory feedback are introduced. Mechanisms of binaural attention and attention switching are covered—as well as how auditory Gestalt rules facilitate binaural understanding. A general blackboard architecture is introduced as an example of how machines can learn to form and interpret aural objects to simulate human cognitive listening. The second part, Configuring and Understanding Aural Space, focuses on the human understanding of complex three-dimensional environments—covering the psychological and biological fundamentals of auditory space formation. This part further addresses the human mechanisms used to process information and interact in complex reverberant environments, such as concert halls and forests, and additionally examines how the auditory system can learn to understand and adapt to these environments. The third part is dedicated to Processing Cross-Modal Inference and highlights the fundamental human mechanisms used to integrate auditory cues with cues from other modalities to localize and form perceptual objects. This part also provides a general framework for understanding how complex multimodal scenes can be simulated and rendered. The fourth part, Evaluating Aural-scene Quality and Speech Understanding, focuses on the object-forming aspects of binaural listening and understanding. It addresses cognitive mechanisms involved in both the understanding of speech and the processing of nonverbal information such as Sound Quality and Quality-of- Experience. The aesthetic judgment of rooms is also discussed in this context. Models that simulate underlying human processes and performance are covered in addition to techniques for rendering virtual environments that can then be used to test these models. The fifth part deals with the Application of Cognitive Mechanisms to Audio Technology. It highlights how cognitive mechanisms can be utilized to create spatial auditory illusions using binaural and other 3D-audio technologies. Further, it covers how cognitive binaural technologies can be applied to improve human performance in auditory displays and to develop new auditory technologies for interactive robots. The book concludes with the application of cognitive binaural technologies to the next generation of hearing aids.
The new realities are here. Virtual and Augmented realities and 360 video technologies are rapidly entering our homes and office spaces. Good quality audio has always been important to the user experience, but in the new realities, it is more than important, it’s essential. If the audio doesn’t work, the immersion of the experience fails and the cracks in the new reality start to show. This practical guide helps you navigate the challenges and pitfalls of designing audio for these new realities. This technology is different from anything we’ve seen before and requires an entirely new approach; this book will introduce the broad concepts you need to know before delving into the practical detail you need. Key Features This book covers audio for all types of new reality technology. At the moment, VR and 360 video are getting a lot of press, but in a few years we will be hearing a lot more about Augmented and Mixed reality technologies as well. A practical guide to creating, designing and implementing audio for this new technology by a leading sound design and implementation expert. Conceptual explanations address the new approaches necessary to designing effective audio for the new realities. Real-world examples and analysis of what does and does not work including detailed case study discussions.
It is anticipated that 3-D sound will become a major component in virtual reality environments. In this thesis, we investigate the development of a Windows(TM) 3-D sound system using binaural technology. This work should eventually be integrated in complex virtual environment software. The 3-D sound effects are achieved by applying a filter pair representing audio cues from a specific point in space to the left and right channels of headphones. As a first step, an offline 3-D audio file generation system is developed, and effects such as sound reflections in a virtual rectangular room are added to this system. The real-time implementation is considered next. The first approach tested for the real-time implementation uses the time domain convolution of a sound source signal with head-related transfer functions, but the computational load of this approach is such that it cannot run in real-time at audio sampling rates. As an alternative, a second approach with a Fast Fourier Transform overlap and save technique is used to reduce the computational load, and a real-time implementation at audio frequencies is therefore successfully achieved.
