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Derivative-Based regularisation of inverse problems in acoustic holography

Year 2019
Thesis Type Master's thesis
Topic Audio Signal Processing
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Alternative discretizations for the numerical evaluation of Rayleigh’s integral based on Fourier acoustics

Authors Pagavino, M.
Year 2019
Thesis Type Audio Engineering project
Topic Audio Signal Processing
Keywords Akustische Holografie
Abstract This audio engineering project deals with the numerial evaluation of sound fields from plane radiators, based on the spatial Fourier method. By the means of the fast Fourier transform it is possible to evaluate the Rayleigh integral at high computational efficiency, a feature that made the near field holography popular in its beginnings. Nowaday, efficiency of the implementation is not a pre-requisite anymore, but it could potentially be advantageous, therefore it is reconsidered in this work. The calculation in via the discrete wave-number domain implies: (i) by the discretization of the propagator, waves propagating in parallel to the radiating plane get singular at some frequencies, and (ii) the inherent spatial periodization of the sound source affects the waves propagating into directions inclined with regard to the plane by interference. The work shows up possible strategies to mitigate these effects. As a thinkable remedy concerning the singularity, a rectangular or triangular interpolant is proposed in 2D, and a trapezoidal one in 3D. The results of FFT-based holography are compared with the correct results of the discretized Rayleigh integral. Moreover, the effects of the alternative discretization interpolants are investigated concerning the inverse holographic problem. The results provided justify the question if, from today's perspective, the FFT-based nearfield acoustic holography is still meaningful, compared to the Rayleigh integral discretized in the space domain.
Supervisors Zotter, F.
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The influence of reverberation on externalization

Authors Giller, P.
Year 2019
Thesis Type Master's thesis
Topic Psychoacoustics
Abstract Realistic binaural synthesis produces well externalized sound images. Externalization is a subjective quantity that refers to the sensation of auditory events being located outside the listener's head. It is a fragile experience which, in addition to the sound field at the entrance of the ear canals, also depends on visual cues, training, and expectation. Various studies have examined perceptual and technical aspects of the phenomenon. It was found that the presence of reverberation can increase the degree of externalization. Furthermore, recent findings indicate the benefit of individual HRTFs may be negligible in reverberant conditions. This work investigates how reverberation influences externalization in a listening experiment, considering different HRTFs and listening conditions. Techniques shall be developed to add helpful reverberation cues to generic HRTFs while preserving the original room impression and sound coloration. Ideally, the results will be integrated in an application for robust binaural rendering of virtual sound scenes.
Supervisors Wendt, F., Höldrich, R.
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Acoustic Analysis of the modern Recorder

Authors Kocher, L.
Year 2019
Thesis Type Bachelor's thesis
Topic Audio Signal Processing
Keywords Klanganalyse
Abstract This thesis considers the acoustic analysis of the so-called Helder Tenor, a modern recorder. Since the Helder Tenor is a rather new instrument and poorly studied, the analysis is focused on the frequency response characteristics and the partial harmonics of the flute. In order to make any conclusions, a baroque model, the most common used recorder model, and two more, are analysed, too. This allows to draw a direct comparison from the new model, which is still in development, to a well-tried model. Ultimately, the thesis should provide an interpretation of the main differences and advantages of the Helder Tenor compared to other, older recorder models.
URL http://phaidra.kug.ac.at/o:79028
Supervisors Höldrich, R.
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Authors Koch, J.
Year 2019
Thesis Type Master's thesis
Topic Audio Signal Processing
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Supervisors Sontacchi, A.
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Interactive virtual walkthrough by position-dependent interpolation of first-order room impulse responses

Authors Müller, K.
Year 2019
Thesis Type Master's thesis
Topic Spatial Audio
Abstract The spatial decomposition method (SDM) enables the mapping of first-order ambisonic room impulse responses to arbitrary higher orders. Thus, a sharper directionality of sound sources and reverberation can be achieved. Based on the SDM an efficient method for position-dependent interpolation of ambisonic room impulse responses will be developed first. Then influences of single components of the utilized approach will be evaluated to achieve a computational efficient algorithm which only deals with the necessary components. Finally, utilizing the position-dependent interpolation of a finite number of measured room impulse responses, a virtual acoustic walk through the room will be possible. To preserve natural acoustics when moving in the virtual room, the real-time capable algorithm is focused on consistent source positions, timbre and room impression related to the reference measurements.
Supervisors Zotter, F., Höldrich, R.
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Distance-coded Ambisonics Formats and their Reproduction on Headphones and Loudspeaker Arrays

Authors Riedel, S.
Year 2019
Thesis Type Audio Engineering project
Topic Spatial Audio
Abstract This work introduces distance-coded Ambisonics formats and their reproduction on headphones and loudspeaker arrays. The first simple and practically motivated format proposes two ambisonic streams, a far-field and a near-field stream, to which sounds are distributed according to a distance parameter at encoding stage. In binaural decoding this enables the application of near-field HRTFs with inherent binaural cues which cannot be applied at encoding stage, for example the frequency-dependent increase in interaural level differences compared to far-field HRIRs. Blending between two ambisonic reverberation patterns (model or measured DRIR) is combined with a physically meaningful level attenuation to achieve a plausible distance effect that includes a change in the direct-to-reverberant sound energy ratio. Compatibility with loudspeaker arrays is given by combining the two ambisonic streams into one single stream after introducing differences in level and the two reverberation patterns to retain a relative distance effect. An efficient and more accurate way to render distance is to restrict the effect to the horizontal plane. Therefore, a second format that interprets negative elevation as the distance of a horizontal source is proposed. In binaural reproduction, this format allows for a high spatial resolution in the precomputation of distance-dependent HRTFs and early reflections, applied at decoding stage. Moreover, this format could motivate future research on loudspeaker systems that employ horizontal sound field synthesis (rendering of near-field sources) combined with AllRAD for elevated sources.
Supervisors Höldrich, R.
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Discrimination of short frequency glides depending on reverberation

Authors Brands, B.
Year 2019
Thesis Type Bachelor's thesis
Topic Psychoacoustics
Abstract Differences in phase or group-delay are crucial properties that help the ear to discriminate between short sounds. To obtain further insights in the ability of short-time discrimination of the auditory system, a forced-choice adaptive listening experiment was performed. The subjects were exposed to chirp-like sounds varying in length, direction of the chirp and added reverberation. These chirp-like sounds were rendered by filtering test-signals with an all-pass filter with logarithmic group-delay. The group-delay was varied and the just notable difference (JND) between the logarithmic group-delay of two stimuli was measured. The results depict that by adding more reverberation, the discrimination decreased. Furthermore, upward chirp-like sounds were discriminable in a better way than downward chirp-like sounds and so were short versus long stimulus lengths. The influence of direction was only significant for short durations.
Supervisors Höldrich, R.
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Tangible user interface for sound field control

Authors Roenisch, T., Haider, M.
Year 2019
Thesis Type Bachelor's thesis
Topic Interaction Design
Keywords Auditory Visual Environment
Abstract Controlling the origin of sound sources in a three-dimensional audio field is a complex task, particularly in a live environment. Since multiple sources can be involved, a good overview, fast access to every source and simple automation commands are required. A user interface should facilitate straightforward handling and situational awareness. The following thesis presents the further development of "A Tangible User Interface for Playing Virtual Acoustics" by Birgit Gasteiger in 2010, with an emphasis on improved usability and advanced Ambisonic-controls and automation. Furthermore, it strives to devine a field of application for the "Tangible User Interface for Auditory Virtual Environments" (TUI-AVE). Several controls for the spatialization of sound sources, the respective development as well as designs of the corresponding visual presentation are outlined.
Supervisors Ritsch, W.
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Room divergence effect in virtual environments

Authors Enge, K.
Year 2019
Thesis Type Master's thesis
Topic Audio Signal Processing
Abstract Virtual reality environments are becoming an increasingly important factor in various applications such as architecture, film and computer games. For a long time, all these areas concentrated primarily on visual impressions. It is undisputed, however, that three-dimensional sound plays an important role in the credibility of virtual environments, if only for the reason that humans characterize real space to a large extent by listening. For the ears, the equivalent of VR glasses is binaural reproduction via headphones. The virtualization of real spaces using CAD-programs opens up new possibilities for psychoacoustic investigations, namely with binaural sounds in virtual spaces. How do virtualization and binaural reproduction influence each other? Does virtualization have an effect on the perceived externalization, distance and direction of binaural reproduction? Can the room divergence effect also be shown in virtual environments? How detailed must spaces be modelled in order to achieve credible experiences for test subjects? Does the possibility of physical movement around a source change the results? Is it possible to "learn" the virtual environment by walking through it? In order to investigate such questions, several spaces with different virtualization techniques will be used: One space by modeling in Unity, one by photo projection on a rectangular virtual space and one by photogrammetry. In these spaces, appropriate psychoacoustic investigations are carried out.
Supervisors Frank, M., Höldrich, R.
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Classification of mechanical noises of motorised cylinder locks

Authors Merz, P.
Year 2019
Thesis Type Audio Engineering project
Topic Audio Signal Processing
Keywords Psychoakustik, Music Information Retrieval
Abstract This thesis examines the classifiability of mechanical noises. The used test data is a set of recordings of motorised cylinder locks, which have been classified according to their build quality. Methods from unsupervised machine learning will be used to study whether it is possible or not to reproduce the classification based on a selection of psychoacoustic features implemented in Python. Finally it will be examined if this classification can also be done automatically.
Supervisors Sontacchi, A.
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Derivative-based regularization of inverse problems in acoustic holography

Authors Pagavino, M.
Year 2019
Thesis Type Master's thesis
Topic Audio Signal Processing
Keywords Akustische Holographie
Abstract The visualization of the sound field close to the source is often helpful to understand the vibroacoustic origin. This gave rise to the development of several acoustic imaging techniques that can be used to model the measured sound field radiated by an arbitrary source. One of these models is the equivalent source method (ESM). It models the local sound field by superimposing distributed elementary sources of different strengths. From spatially discrete sound pressure measurements, the strength of these sources can be determined through solving a linear inverse problem. Due to the underdetermined and ill-posed nature of the inverse problem, the introduction of some form of regularization is a prerequisite for obtaining a meaningful solution. Imposing additional constraints on the solution to enforce expected spatial structures can provide suitable regularization. Inverse problems with constraints typically minimize some norm functional acting on the spatial domain. Sparsity promotion through Compressive Sensing, based on L1-norm minimization, has received increasing attention in recent years due to its ability of providing solutions that are valid beyond the spatial sampling limit. However, typical vibroacoustic source phenomena are not necessarily spatially sparse themselves, as they frequently contain spatially distributed patterns as well. This thesis regards regularization methods that impose sparsity on first- and second-order spatial derivatives. This promotes piecewise constant or linear solutions with minimum curvature as a more probable spatial constraint. Such regularizers are heavily used in various fields of image processing. They were only recently introduced in acoustics, where they have consistently proven to effectively model common structures. In this thesis, I propose to adapt the Schatten-norms of the Hessian as regularizers, which to the best of my knowledge has not been considered for acoustic holography yet. What is more, a fused approach is considered where additional sparsity is imposed on the spatial domain, suitable for the characterization of sparse and extended sources. A proximal splitting algorithm is adopted to solve the minimization problem, which allows an efficient implementation of the proposed regularizers. This work provides the fundamental understanding of derivative-based regularization and reveals its characteristics and abilities. The proposed methods are investigated and verified by numerical simulations and by using measurements obtained from an experimental setup. The required theory behind the algorithm is examined and a detailed exposition of its use is provided.
Supervisors Zotter, F., Höldrich, R.
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Derivative-Based Regulatisation of inverse problems in acoustic holography

Authors Pacher, S.
Year 2019
Thesis Type Bachelor's thesis
Topic Algorithmic Composition
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ELSE: An Artistic Study on Algorithmic Agency in Sound Synthesis Composition

Authors Pozzi, D.
Year 2018
Thesis Type Computer Music project
Topic Algorithmic Composition
Abstract This article presents the development of a SuperCollider patch as a case study of the influence of algorithmic processes and algorithmic thinking in computer music practice. The crucial stages involved in the experimental design of a sound synthesis algorithm are analysed from a critical perspective that aims at exploring the multifaceted dynamics underpinning the relationship between artist and algorithmic process. In doing this, I’ll try to highlight the different agencies that contribute to shape the creative process of composing music with computers. It is suggested that the process of constant reconfiguration, intended as the iterative adaptation that takes place between an artist and the algorithms employed, has a major generative role in algorithmic practice. We may identify this generative element as one specific expression of the agency of the algorithmic. The case study is based on a retrospective documentation of Else, a generative algorithm conceived and realised in SuperCollider.
URL http://phaidra.kug.ac.at/o:77435
Supervisors Pirrò, D.
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Perceptually Motivated Ambient Scene Recording and Parametric Source Embedding

Authors Frauscher, E.
Year 2018
Thesis Type Master's thesis
Topic Audio Signal Processing
Keywords Spatial Audio
Abstract Various auditory experiments rely on the availability of highly authentic or highly plausible reference reproductions of real acoustic environments, for which the required capture, reproduction, and customization methods are investigated in this work. Most of the current approaches are based on simulated room impulse responses which allows a great freedom in customization; however, they can still be challenging as not all simulation settings will sound natural. As an alternative, this thesis targets a hybrid spatial recording and reproduction technique that allows to record real 3-dimensional acoustic scenes, and to customize them by parameterising embedded source material or the given recording by modifying its content. To preserve naturalness, parameterization requires to utilize estimated sound field parameters derived either from features captured in the recording environment or the recording itself. The proposed capture and parameterization approaches target loudspeaker-based reproduction. They are tested against reference dummy head and main microphone recordings in listening experiments to evaluate their authenticity and plausibility, among some relevant attributes.
Supervisors Zotter, F., Höldrich, R.
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Akustische Warnsignale und Verkehrslärmumgebung: Wiedererkennbarkeit und wahrgenommene Dringlichkeit von Fahrradklingeln

Authors Frohmann, L.
Year 2018
Thesis Type Bachelor's thesis
Topic Sonification
Keywords Psychoakustik
Abstract Raising awareness about how alarm sounds are perceived and evaluated by an individual in traffic scenery is important for developing new alarm designs, as well as for improving existing ones. Bearing a positive contribution to road safety, cyclists and pedestrians especially can benefit from appropriate alarming bell and horn sounds. This work focuses on the perception of urgency for various types of bicycle bells, as well as on acoustical descriptors influencing our judgement. The conducted listening experiments reveil the recognizability of bike bells among other everyday sounds and show urgency scores for testing in both silent surrounding and with additional traffic noise background. The results support a warning sound ranking in terms of efficiency and lead to an objective urgency model formed by spectral and temoral sound parameters.
URL http://phaidra.kug.ac.at/o:76982
Supervisors Höldrich, R., Weger, M.
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Optimum-phase primal signal and radiation-filter modelling of musical instruments

Authors Zagala, F.
Year 2018
Thesis Type Master's thesis
Topic Spatial Audio
Abstract Capture of musical instruments including directivity by spherically surrounding microphone array often leads to either overly complex radiation patterns or destructive interferences at high frequencies. There, small differences in the distance from the instrument to each of the microphones yield different arrival times in the captured signal and hereby large phase differences. Therefore, be it by linear triangular or spherical harmonics interpolation, frequency-independent directional interpolation of the microphone signals can result either in spectral degradation or in a shift of the signal energy to higher orders; especially affecting high frequencies. In this work, an analysis method is proposed in order to decompose directional signals of any measured instrument into an interference-free primal signal and a directivity filter. Both the directivity filter and the primal source signal utilise only the short-term spectral magnitude of each microphone signal in order to avoid artefacts. The magnitudes are complemented by a simplified phase using phase-retrieval techniques
URL http://phaidra.kug.ac.at/o:79029
Supervisors Höldrich, R., Zotter, F.
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Waterside - Die Entwicklung eines Audio Games

Authors Böhm, J.
Year 2018
Thesis Type Bachelor's thesis
Topic Algorithmic Composition
Abstract Diese Bachelorarbeit ist im Rahmen des Seminars ”Computermusik und Medienkunst“ zum Thema ”Audio Games“ entstanden. Im Unterschied zu traditionell eher visuell orientierten Computerspielen spielt in Audio Games der H¨orsinn eine zentrale Rolle. Im Zuge des Seminars wurde von jedem teilnehmenden Studierenden ein eigenes Audio Game konzipiert und als Prototyp implementiert. In dieser Arbeit werden zunächst Spiele im Allgemeinen – bis hin zu Audio Games im Speziellen – aus unterschiedlichen Perspektiven beleuchtet. Kern dieser Arbeit ist die Dokumentation des Designs und der Implementation eines Jump’n’Run Gehörbildungs-Lernspiels. Im Spiel – Waterside – werden auditiv vermittelte Aufgabenstellungen innerhalb einer zweidimensionalen Spielwelt durch ”physikalische“ Interaktion mit visualisierten Lösungsmöglichkeiten beantwortet. Die zu lösenden Aufgaben sind vom Seashore Test inspiriert und sollen eine spielerische Vorbereitung für diesen ermöglichen.
URL http://phaidra.kug.ac.at/o:76977
Supervisors Zmölnig, J.
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Calculation and Validation of the Noise Emission of Electric Machines

Authors Reitz, L.
Year 2018
Thesis Type Master's thesis
Topic Audio Signal Processing
Keywords Technische Akustik
Abstract The recent development of more powerful computers makes the simulation of electrical engines as data source for the computation of its noise emission, as opposed to measurements on the real object, more and more attractive. This work shall contribute to the response to the question to what extent Finite Element Method (FEM) based Multi-Body-Simulation (MBS) computation and noise emission computation are suited for qualitative and quantitative assessment of electric machines and where there is need for further research. At the focal point there are objective criteria such as torsional oscillation, level of structure-borne noise and noise level. Especially the accuracy of results, frequency range, model accuracy, and model depth should be put in the center of attention. A comparison of simulation results and existing measurement results is therefore executed. The simulation is carried out using a SIMULINK-model in combination with a commercial MBS-tool. Within the Multi-Body-Simulation the excitation of the chassis originating from the magnetic field is considered and from there first the structure-borne noise on the stator surface and subsequently the air-borne noise are calculated. The master’s thesis is conducted on behalf of and in cooperation with AVL List GmbH.
URL http://phaidra.kug.ac.at/o:73333
Supervisors Sontacchi, A., Pomberger, H.
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Attractive Correlations

Authors Giannoutakis, K.
Year 2018
Thesis Type Master's thesis
Topic Algorithmic Composition
Abstract This thesis presents the performance ecosystem “Attractive Correlations”. In the emerging field of the ecosystemic framework in music, an overlooked conviction seems to contradict a fundamental principle in this line of creative thought. “Attractive Correlations” propose new directions for dealing with the problematic of the reduced ability of experiencing some of the reciprocal relationships between the involved agencies. The methods that were implemented in the artistic work and investigated in this thesis are: the dissolution of the central stage by the installative articulation of space with various smaller stages and spots, the dynamic alteration of listening modes for the human-agents, the reduced influence of the agency of technocratic determinism via dynamical DSP routines, the extension of the algorithmicity in a perceivable performative domain and the audience conditioning through preparatory events and unconventional concert configurations.
URL http://phaidra.kug.ac.at/o:73300
Supervisors Eckel, G.
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"El Camino" Texturbasiertes Komponieren in der Computermusik

Authors Mayer, J.
Year 2018
Thesis Type Bachelor's thesis
Topic Algorithmic Composition
Abstract „El Camino“ (dt. der Weg) ist Titel und Thema sowohl des künstlerischen Klangstücks wie auch der vorliegenden schriftlichen Arbeit. Diese versteht sich einerseits retrospektiv als ideologische wie auch technisch-handwerkliche Dokumentation, andererseits auch als tiefer gehende Betrachtung und Kontextualisierung des künstlerisch-kreativen Zugangs an das genannte Stück. Dass sich hierbei Texturen zum zentralen Bedeutungsschwerpunkt erheben, suggeriert bereits der Untertitel der Arbeit. Der Weg, den es hierbei zu beschreiten gilt, beginnt zunächst mit der Auseinandersetzung mit Begrifflichkeiten (Kapitel 2), welche sich sowohl in der vorliegenden Arbeit wie auch möglicherweise darüber hinaus als Hilfsmittel zur Beschreibung klanglicher Phänomene begreifen lassen. So sollen hier Begriffe wie „Textur“, „Drone“ und „Geste“ einander gegenübergestellt und miteinander verglichen sowie auch deren Misch- bzw. Übergangsformen herausgestellt werden. Fortgesetzt wird die Wanderung mit Kapitel 3 mit einer Darstellung jener Inspirationsquellen, welche sich für das eigene Schaffen in mannigfaltiger Hinsicht als – im buchstäblichen Sinne – wegweisend zeichnen. Kern-Wegstück der Arbeit ist unmissverständlich Kapitel 4, der Weg – „El Camino“ – per se. Hier sollen einerseits metaphorisch-ideologische Überlegungen zum Stück angestellt, andererseits dessen Entstehungsprozess sowohl künstlerisch als auch technisch umrissen werden. Um dem Untertitel der vorliegenden Arbeit gerecht zu werden, sollen in diesem Zusammenhang drei unterschiedliche repräsentative Klangtexturen des Stücks eingehend beleuchtet werden, was mit einer groben Erläuterung des zugrunde liegenden Programmiercodes mit entsprechendem klanglichen Resultat einhergeht.
URL http://phaidra.kug.ac.at/o:73329
Supervisors Ciciliani, M.
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Musicking - kammermusikalische Aspekte in "together - alone" und "encounters"

Authors Trenkwalder, A.
Year 2018
Thesis Type Bachelor's thesis
Topic Algorithmic Composition
Abstract In der vorliegenden Bachelorarbeit beschreibe ich zwei Stücke für Instrumente mit Live-Elektronik, die sich mit der Frage der „kammermusikalischen Qualitäten“ von Live-Elektronik künstlerisch auseinandersetzen. Zu diesem Zeitpunkt stellten sich mir folgende Fragen: „Wie kann ich Live-Elektronik als einen gleichwertigen Partner zu einem Instrumentalisten etablieren bzw. vice versa?“ „Welche Formen der Interaktion zwischen Instrumentalist und Live-Elektronik-Musiker sind möglich?“ „Welche Rolle spielt physische Präsenz beim Musizieren (mit Live-Elektronik)?“ Diese Fragen werden in den Stücken together – alone und encounters auf verschiedene Weise behandelt und bilden die Grundlage für diese Bachelorarbeit.
URL http://phaidra.kug.ac.at/o:73303
Supervisors Eckel, G.
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Das soziopolitische Potential von Raumakustik im Angesicht zeitgenössischer Gestaltungsmöglichkeiten

Authors Manhartsberger, A.
Year 2018
Thesis Type Bachelor's thesis
Topic Algorithmic Composition
Abstract Ausgangspunkt der Arbeit bilden zwei, musikalische Strömungen nach 1950, deren soziopolitische Forderungen zum fruchtbaren Boden künstlerischer Auseinandersetzung mit Raum werden sollten. Der historische Abriss ist als selektive Interpretation vorliegender Quellen zu deuten, um jene Aspekte zu verdeutlichen, die meiner Meinung nach im Kontext elektronischer Raummusik nach wie vor von Bedeutung sind. Durch den Exkurs in die Raumsoziologie und den Verweis auf die Phänomenologie der Wahrnehmung, soll die folgende Argumentation in den zeitgenössischen Diskurs der Konstitution von Raum, gebettet werden. Den Hauptteil bildet die Besprechung von zwei Installationen und einem fixed-media Stück eigener Praxis, für deren Realisierung die Auseinandersetzung mit Raum und seinen sozialen und soziopolitischen Wirkungen zentral von Bedeutung wurde. Motivation dieser Arbeit ist meine Ansicht, dass wir als Komponist*innen besonders heute, in Zeiten des zunehmendem politischen Totalitarismus und dem Verfall der Demokratie, dazu aufgerufen sind, die zur Verfügung stehenden künstlerischen Mittel zu erkennen, um gestalterisch am Konstitutionsprozess der gesellschaftlichen Wirklichkeit, teilzunehmen.
URL http://phaidra.kug.ac.at/o:73304
Supervisors Ciciliani, M.
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DIY Mixed Order Ambisonics Microphone Array

Authors Romanov, M.
Year 2018
Thesis Type Audio Engineering project
Topic Spatial Audio
Abstract In this work a Mixed-Order-Ambisonics microphone is build. Several approaches to equalize spherical microphones are presented and the easiest way used by multichannel filters to achieve a good sounding result. The idea here is to build a cheap microphone array that can compete with others available on the market. Also it must be easy to build alone without assuming to much theory so everyone can do this at home.
URL http://phaidra.kug.ac.at/o:73334
Supervisors Ritsch, W.
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Compact spherical loudspeaker arrays: new filter and layout ideas

Authors Riedel, S.
Year 2018
Thesis Type Master's thesis
Topic Spatial Audio
Abstract Compact spherical loudspeaker arrays employ modal beam forming techniques to precisely excite wall reections. In its performance practice it turned out that it is mostly the horizontal plane, in which walls and reectors are close enough to create distinct auditory objects in space. Moreover, human sound localization is known to be more precise in the horizontal plane. This motivates the development of mixed-order control and dedicated mixed-order arrays that concentrate their loudspeakers in the horizontal plane. Furthermore, this thesis presents a two-band approach for the control of spherical loudspeaker arrays. In the lower band, spherical beamforming is feasible and fast crosstalk-cancellation lters can be designed. In the higher band, where beamforming is impaired due to spatial aliasing and uncontrolled interferences between the loudspeakers, an amplitude panning approach based on AllRAD is employed.
Supervisors Zotter, F.