Assembled landscapes: The sites and sounds of some recent shakuhachi recordings

This article examines the folding together of music and landscape in some recent albums featuring the shakuhachi, a Japanese bamboo flute that today animates an active and international music scene. Through analysis of the texts, images, and sounds on these albums, I explore the reimagining of the shakuhachi's musical geography as the instrument reaches new players and places in Europe, Australia, and North America. Using recordings that incorporate environmental sounds alongside the shakuhachi, I examine ideas about the perceived authenticity of particular sounds, performance spaces, and recording aesthetics. These recordings unsettle our thinking about the relationship between music and landscape in several ways. First they document performers' connections with particular sites, yet complicate any notion that the shakuhachi is related to a single place or nation, signalling a distinctly contemporary sense of place. Second, the centrality of mediation in these artistic projects makes technology crucial to the production of the natural and renders the naturalness of the shakuhachi audible in new ways. Third, the use of environmental sounds provokes questions about agency and the boundaries between human and non-human sound-making. By treating these albums as assemblages of material, social, technological, and natural elements, I reveal the lively and complex character of otherwise everyday musical objects

Archaeologies of Sound: Reconstructing Louis MacNeice’s Wartime Radio Publics

This article approaches the problem of reconstructing the culturally situated audience experience of radio programming through the example of Louis MacNeice's wartime radio broadcasts, notably "Alexander Nevsky" and "Christopher Columbus". The article draws on audience research reports, internal correspondence, and close analysis of the broadcasts themselves in order to triangulate a listening experience that, though it ultimately cannot be recovered, can be better understood through its proximate cultural traces

Application of sound source separation methods to advanced spatial audio systems

This thesis is related to the field of Sound Source Separation (SSS). It addresses the development and evaluation of these techniques for their application in the resynthesis of high-realism sound scenes by means of Wave Field Synthesis (WFS). Because the vast majority of audio recordings are preserved in twochannel stereo format, special up-converters are required to use advanced spatial audio reproduction formats, such as WFS. This is due to the fact that WFS needs the original source signals to be available, in order to accurately synthesize the acoustic field inside an extended listening area. Thus, an object-based mixing is required. Source separation problems in digital signal processing are those in which several signals have been mixed together and the objective is to find out what the original signals were. Therefore, SSS algorithms can be applied to existing two-channel mixtures to extract the different objects that compose the stereo scene. Unfortunately, most stereo mixtures are underdetermined, i.e., there are more sound sources than audio channels. This condition makes the SSS problem especially difficult and stronger assumptions have to be taken, often related to the sparsity of the sources under some signal transformation. This thesis is focused on the application of SSS techniques to the spatial sound reproduction field. As a result, its contributions can be categorized within these two areas. First, two underdetermined SSS methods are proposed to deal efficiently with the separation of stereo sound mixtures. These techniques are based on a multi-level thresholding segmentation approach, which enables to perform a fast and unsupervised separation of sound sources in the time-frequency domain. Although both techniques rely on the same clustering type, the features considered by each of them are related to different localization cues that enable to perform separation of either instantaneous or real mixtures.Additionally, two post-processing techniques aimed at improving the isolation of the separated sources are proposed. The performance achieved by several SSS methods in the resynthesis of WFS sound scenes is afterwards evaluated by means of listening tests, paying special attention to the change observed in the perceived spatial attributes. Although the estimated sources are distorted versions of the original ones, the masking effects involved in their spatial remixing make artifacts less perceptible, which improves the overall assessed quality. Finally, some novel developments related to the application of time-frequency processing to source localization and enhanced sound reproduction are presented.Cobos Serrano, M. (2009). Application of sound source separation methods to advanced spatial audio systems [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8969Palanci

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

Towards soundscape fingerprinting: development, analysis and assessment of underlying acoustic dimensions to describe acoustic environments

Soundscape according to the definition in ISO 12913-1 describes an acoustic environment as perceived by humans in context. In order to be able to assess a soundscape holistically, the components acoustic environment, person and context should be described sufficiently to enable triangulation. Person-based soundscape assessment has been the subject of extensive research over the past decades to date, leading to a good understanding of the main emotional dimensions. On the acoustic side, e.g., in modeling emotional responses by acoustic features, parameters describing loudness are widely used, also from the point of view of legal regulations. These parameters are often complemented by established psychoacoustic measures. However, it is unknown to what extent these parameters are suitable to adequately describe and compare acoustic environments for hypotheses concerning humans. The presented dissertation aims to contribute to this field by means of an exploratory, empirical, and data-based approach. First, the general requirements of the aim – the description of acoustic environments – are defined and accompanied with concepts and findings from current research areas. Subsequently a methodology is developed that allows for the identification of underlying acoustic dimensions on the basis of empirical observational data of real world acoustic environments by means of multivariate statistical methods. It contains considerations on the physical sound field, the human auditory system, as well as appropriate signal processing techniques. The methodology is then applied to an exemplary extensive dataset of various Ambisonics soundscape recordings. The resulting expressions of the acoustic dimensions are evaluated and discussed with respect to plausibility and perceptual consistency. Finally, two application examples are presented to further validate the methodology and to test the applicability of acoustic dimensions in concrete research scenarios. It was found that the presented methodology is suitable to identify dimensions for the description of acoustic environments. Furthermore, the dimensions found form a suitable basis for further soundscape analyses.Soundscape (nach ISO 12913-1) beschreibt eine akustische Umgebung, wie sie von Menschen im Kontext wahrgenommen wird. Eine ganzheitliche Beurteilung einer Soundscape wird demnach durch Triangulation der Aspekte akustische Umgebung, Person und Kontext hergestellt. Die personenbezogene Bewertung von Soundscapes war und ist bis heute Gegenstand umfangreicher Forschungsarbeiten, die zu einem weitreichendem Verständnis der wichtigsten emotionalen Dimensionen geführt haben. Auf der akustischen Seite sind Parameter weit verbreitet, die die Lautstärke beschreiben. Ergänzt werden diese Parameter oft durch etablierte psychoakustische Größen. Unbekannt ist jedoch, inwieweit diese (psycho-)akustischen Parameter tatsächlich geeignet sind, Soundscapes zu beschreiben und zu vergleichen hinsichtlich den Menschen betreffender Hypothesen. Hierzu soll diese Dissertation einen Beitrag leisten. Der dabei verfolgte Ansatz ist explorativ, empirisch und datenbasiert. Zunächst werden Anforderungen an das Ziel – die Beschreibung akustischer Umgebungen – definiert und mit Konzepten aus aktuellen Forschungsgebieten ergänzt. Anschließend wird eine Methodik entwickelt, die es erlaubt, fundamentale akustische Dimensionen zu identifizieren auf der Basis empirischer Beobachtungsdaten realer akustischer Umgebungen und mit Hilfe multivariater statistischer Methoden. Sie enthält Überlegungen zum physikalischen Schallfeld, zur menschlichen Hörwahrnehmung sowie zu geeigneten Signalverarbeitungstechniken. Die Methodik wird anschließend auf einen beispielhaften Datensatz von Ambisonics Soundscape-Aufnahmen angewandt. Die resultierenden akustischen Dimensionen werden hinsichtlich ihrer Plausibilität und wahrnehmungsbezogenen Konsistenz diskutiert. Schließlich werden zwei Anwendungsbeispiele vorgestellt, um die Methodik weiter zu validieren und um die Anwendbarkeit der akustischen Dimensionen in konkreten Forschungsszenarien zu testen. Hierbei kann festgestellt werden, dass die gefundenen Dimensionen einen hohen Grad an Varianz akustischer Umgebungen erklären können und gut interpretierbar sind. Sie bilden somit eine geeignete Grundlage für die hier dargestellte Analyse von Soundscapes. Die Methodik ist dabei variabel erweiterbar, sodass vielfältige Anwendungen und Forschungsarbeiten bzgl. akustischer Umgebungen ermöglicht werden

Real-time Microphone Array Processing for Sound-field Analysis and Perceptually Motivated Reproduction

This thesis details real-time implementations of sound-field analysis and perceptually motivated reproduction methods for visualisation and auralisation purposes. For the former, various methods for visualising the relative distribution of sound energy from one point in space are investigated and contrasted; including a novel reformulation of the cross-pattern coherence (CroPaC) algorithm, which integrates a new side-lobe suppression technique. Whereas for auralisation applications, listening tests were conducted to compare ambisonics reproduction with a novel headphone formulation of the directional audio coding (DirAC) method. The results indicate that the side-lobe suppressed CroPaC method offers greater spatial selectivity in reverberant conditions compared with other popular approaches, and that the new DirAC formulation yields higher perceived spatial accuracy when compared to the ambisonics method