On the plausibility of simplified acoustic room representations for listener translation in dynamic binaural auralizations

Diese Doktorarbeit untersucht die Wahrnehmung vereinfachter akustischer Raumrepräsentationen in positionsdynamischer Binauralwiedergabe für die Hörertranslation. Die dynamische Binauralsynthese ist eine Audiowiedergabemethode zur Erzeugung räumlicher auditiver Illusionen über Kopfhörer für virtuelle, erweiterte und gemischte Realität (VR/AR/MR). Dabei ist es nun eine typische Anforderung, immersive Inhalte in sechs Freiheitsgraden (6DOF) zu erkunden. Dynamische binaurale Schallfeldimitationen mit hoher physikalischer Genauigkeit zu realisieren, ist meist mit sehr hohem Rechenaufwand verbunden. Frühere psychoakustische Studien weisen jedoch darauf hin, dass Menschen eine begrenzte Empfindlichkeit gegenüber den Details des Schallfelds haben, insbesondere im späten Nachhall. Dies birgt das Potential physikalischer Vereinfachungen bei der positionsdynamischen Auralisation von Räumen. Beispielsweise wurden Konzepte vorgeschlagen, die auf der perzeptiven Mixing Time oder der Hörbarkeitsschwelle von frühen Reflexionen basieren, für welche jedoch eine gründliche psychoakustische Bewertung noch aussteht. Zunächst wurde ein Aufbau zur positionsdynamischen Raumauralisation implementiert und evaluiert. Daran untersucht die Arbeit wesentliche Systemparameter wie die erforderliche räumliche Auflösung eines Positionsrasters für die dynamische Anpassung. Da allgemein etablierte Testmethoden zur wahrnehmungsbezogenen Bewertung von räumlichen auditiven Illusionen unter Berücksichtigung interaktiver Hörertranslation fehlten, untersucht die Arbeit verschiedene Ansätze zur Messung der Plausibilität. Auf dieser Grundlage werden physikalische Vereinfachungen im Verlauf des Schallfeldes in positionsdynamischen binauralen Auralisationen der Raumakustik untersucht. Für die Hauptexperimente wurden binaurale Raumimpulsantworten (BRIRs) entlang einer Linie für die Hörertranslation in einem eher trockenen Hörlabor und einem halligen Seminarraum ähnlicher Größe gemessen. Die erstellten Datensätze enthalten Szenarien von Hörerbewegungen auf eine virtuelle Schallquelle zu, daran vorbei, davon weg oder dahinter. Darüber hinaus betrachten die Untersuchungen zwei Extremfälle der Quellenorientierung, um die Auswirkungen einer Variation der Schallquellenrichtcharakteristik zu berücksichtigen. Die BRIR-Sätze werden systematisch bearbeitet und vereinfacht, um die Auswirkungen auf die Wahrnehmung zu bewerten. Insbesondere das Konzept der perzeptiven Mixing Time und manipulierte räumlich-zeitliche Muster früher Reflexionen dienten als Testfälle in den psychoakustischen Studien. Die Ergebnisse zeigen ein hohes Potential für Vereinfachungen, unterstreichen aber auch die Relevanz der genauen Imitation prominenter früher Reflexionen. Die Ergebnisse bestätigen auch das Konzept der wahrnehmungsbezogenen Mixing Time für die betrachteten Fälle der positionsdynamischen binauralen Wiedergabe. Die Beobachtungen verdeutlichen, dass gängige Testszenarien für Auralisierungen, Interpolation und Extrapolation nicht kritisch genug sind, um allgemeine Schlussfolgerungen über die Eignung der getesteten Rendering-Ansätze zu ziehen. Die Arbeit zeigt Lösungsansätze auf.This thesis investigates the effect of simplified acoustic room representations in position-dynamic binaural audio for listener translation. Dynamic binaural synthesis is an audio reproduction method to create spatial auditory illusions over headphones for virtual, augmented, and mixed reality (AR/VR/MR). It has become a typical demand to explore immersive content in six degrees of freedom (6DOF). Realizing dynamic binaural sound field imitations with high physical accuracy requires high computational effort. However, previous psychoacoustic research indicates that humans have limited sensitivity to the details of the sound field. This fact bears the potential to simplify the physics in position-dynamic room auralizations. For example, concepts based on the perceptual mixing time or the audibility threshold of early reflections have been proposed. This thesis investigates the effect of simplified acoustic room representations in position-dynamic binaural audio for listener translation. First, a setup for position dynamic binaural room auralization was implemented and evaluated. Essential system parameters like the required position grid resolution for the audio reproduction were examined. Due to the lack of generally established test methods for the perceptual evaluation of spatial auditory illusions considering interactive listener translation, this thesis explores different approaches for measuring plausibility. Based on this foundation, this work examines physical impairments and simplifications in the progress of the sound field in position dynamic binaural auralizations of room acoustics. For the main experiments, sets of binaural room impulse responses (BRIRs) were measured along a line for listener translation in a relatively dry listening laboratory and a reverberant seminar room of similar size. These sets include scenarios of walking towards a virtual sound source, past it, away from it, or behind it. The consideration of two extreme cases of source orientation took into account the effects of variations in directivity. The BRIR sets were systematically impaired and simplified to evaluate the perceptual effects. Especially the concept of the perceptual mixing time and manipulated spatiotemporal patterns of early reflections served as test cases. The results reveal a high potential for simplification but also underline the relevance of accurately imitating prominent early reflections. The findings confirm the concept of the perceptual mixing time for the considered cases of position-dynamic binaural audio. The observations highlight that common test scenarios for dynamic binaural rendering approaches are not sufficiently critical to draw general conclusions about their suitability. This thesis proposes strategies to solve this

Space in electroacoustic music: composition, performance and perception of musical space

This thesis concerns space as an essential element of expression and communication in electroacoustic music. It shows that musical space is a complex term which refers to many different aspects of composition, performance and perception of electroacoustic music. It is argued that space is a compound musical element which can be integrated into the compositional structure to a degree where space becomes the primary canier of meaning in the work, and that the creation and interpretation of this meaning is a result of learned cultural aspects of interpersonal communication in terms of personal space and territoriality. Furthermore, the close relationship between electroacoustic music composition and technology is acknowledged, and the influence of available technology on aesthetic choices and decision making with regard to spatial composition and performance is taken into consideration. The structure for the investigation is based on a model of musical space comprising three basic levels: 1) spatial properties of individual sounds in terms of intrinsic space, extrinsic space and spectral space, 2) the spatial arrangement of individual sounds and events into a composed space which is played in, and becomes affected by, the listening space, and 3) the perceived space, which constitutes the listening experience of the combination of composed space and listening space. A framework for describing and analysing spatial elements in electroacoustic composition is proposed. The discussion and findings are largely based on my experience as a listener, composer and performer of electroacoustic music, and in addition finds support in research on auditory perception, particularly Jens Blauert's work on spatial hearing and Albert Bregman's auditory scene theory, as well as Denis Smalley's spectromorphological theory, James Tenney's writings on perception-based music listening and analysis, and Edward T. Hall's investigations into space as an element of non-verbal communication

Proceedings of the EAA Joint Symposium on Auralization and Ambisonics 2014

In consideration of the remarkable intensity of research in the field of Virtual Acoustics, including different areas such as sound field analysis and synthesis, spatial audio technologies, and room acoustical modeling and auralization, it seemed about time to organize a second international symposium following the model of the first EAA Auralization Symposium initiated in 2009 by the acoustics group of the former Helsinki University of Technology (now Aalto University). Additionally, research communities which are focused on different approaches to sound field synthesis such as Ambisonics or Wave Field Synthesis have, in the meantime, moved closer together by using increasingly consistent theoretical frameworks. Finally, the quality of virtual acoustic environments is often considered as a result of all processing stages mentioned above, increasing the need for discussions on consistent strategies for evaluation. Thus, it seemed appropriate to integrate two of the most relevant communities, i.e. to combine the 2nd International Auralization Symposium with the 5th International Symposium on Ambisonics and Spherical Acoustics. The Symposia on Ambisonics, initiated in 2009 by the Institute of Electronic Music and Acoustics of the University of Music and Performing Arts in Graz, were traditionally dedicated to problems of spherical sound field analysis and re-synthesis, strategies for the exchange of ambisonics-encoded audio material, and – more than other conferences in this area – the artistic application of spatial audio systems. This publication contains the official conference proceedings. It includes 29 manuscripts which have passed a 3-stage peer-review with a board of about 70 international reviewers involved in the process. Each contribution has already been published individually with a unique DOI on the DepositOnce digital repository of TU Berlin. Some conference contributions have been recommended for resubmission to Acta Acustica united with Acustica, to possibly appear in a Special Issue on Virtual Acoustics in late 2014. These are not published in this collection.European Acoustics Associatio

Mapping gestures in the creation of intangible artworks

"Mapping gestures in the creation of intangible artworks" considers that what is normally understood as an artwork, such as a painting or music, is in fact a tangible thing experienced via excitation of the physical senses. It is the perceiver's interpretation of this excitation that creates their unique experience of the object, and this interpretation creates the artwork. Rather than a linear, single-trajectory interaction from the art-maker to the art-perceiver, “Mapping gestures ...” hypothesises that this relationship is best understood as having the qualities of a Möbius strip, in that the maker and perceiver are engaged in an interaction in which each are simultaneously creator and perceiver. "Mapping gestures ...” has two parts: the three art-objects, MOTION, SPEECH and VISION, and the accompanying exegesis, which discusses the ideas and processes that informed their development. Its process is to explore the making of these art-objects and the discoveries that that generates. These discoveries in turn influence the process of creating the art-objects, which consequently leads to more discoveries. MOTION, SPEECH, and VISION are designed to engage the perceiver both physically and mentally, and to represent that engagement through simultaneously showing the result of their physical and their mental interactions with it. "Mapping gestures in the creation of intangible artworks" coalesces a bricolage of diverse aspects, including: concepts and theories relating to art making and communication, various art works, and art making concepts and processes, into a set of art-objects that overtly, fundamentally, and in essence rely on the interaction and interpretation of the perceiver in order to become artworks

Groove in Cuban Dance Music: An Analysis of Son and Salsa

The rhythmic feel or 'groove' of Cuban dance music is typically characterised by a dynamic rhythmic energy, drive and sense of forward motion that, for those attuned, has the ability to produce heightened emotional responses and evoke engagement and participation through physical movement and dance. No single work on groove in Cuban dance music considers together the cognitive, cultural, socio-musical and emotional dimensions of the music-making practices and aesthetics that characterise groove production. This study integrates these perspectives into a single theoretical framework with the aim of gaining fresh insights into the nature of groove in two prominent styles of Cuban and Cuban-related dance music: son and salsa. Methodologically, this study blends ethnography and the analysis of timing data extracted from real-world performances to explore the shared cultural knowledge, socio-musical processes, aesthetics and emotional dimensions of groove. Ethnography facilitates the detailed investigation of how performers talk about the music-making practices that characterise aspects of musical culture while the use of timing data, recorded in situ, facilitates the investigation of the real-time nuanced micro-timing relationships that shape effective groove production. The findings of this study paint a picture of groove that is rich, complex and multidimensional, one that is built upon the expressive performances, socio-musical interactions and collectivist attitudes of rhythm section musicians as well as powerful cultural models and intersubjectively shared knowledge. When rhythm section musicians engage in expressive and interactive dialogues and work effectively as a synchronous collective, the resultant groove embodies the dynamic rhythmic, communicative and emotional energies of the individuals that comprise the group. In performance situations, when the groove of the rhythm section spontaneously finds union with the kinaesthetic and emotional energies of dancers and audiences, the cumulative energy possesses the power to inspire, excite, energise, invite participation and unite people in joyous celebration