Syftet med undersökningen är att förstå och beskriva problemen för produktionstekniker och konstnärliga ledare om rumsljudens betydelse under fjärrproduktion av virtuell teater, som är användbar för att skapa upplevd närvaro vid fjärrproduktion till publiken, skådespelarna och slutprodukten. Deltagande observation, intervjuer och webbenkät har använts som metoder för materialinsamling. Hur agerade produktionstekniker och konstnärliga ledare för att via fiber fjärrproducera närvaro under en direktsänd virtuell teater där produktionsteam, skådespelare och publik befann sig på tre platser i Norden? Tidigare forskning har pekat på ljudets betydelse för upplevd närvaro hos publiken och lyckad fjärrproduktion via fibernätet har därför benämnts som presence production (Knudsen, 2004). Forskning har även gjorts om inspelningspraxis av klassisk musik där ett imaginärt rum har betydelse för att göra musiken levande (Burlin, 2008). För analys och beskrivning av resultatet har en teori om förändringarna av konstnärers och hantverkarnas verksamhet, där hantverkarna börjar etablera sig i konstvärlden och konstnärerna börjar etablera sig i hantverkarnas värld, då de båda ser potentiella problem som kan lösas (Becker, 1978). Sedan en teori om olika roller för musikproducenter och om en produktion är dokumenterande eller producerande (Gullö, 2010). Deltagande observationen av den fjärrproducerade virtuella teatern visade att produktionstekniker och konstnärliga ledare saknade kunskapen att skapa och producera rumsljud som kunde öka skådespelarens och publikens upplevelse av närvaro. Observationerna visade även att som ensam ljudtekniker så är det svårt att hinna producera tre rumsljud, en för skådespelaren, en för publiken och en för virtuella teatern.

This thesis investigates the feasibility of using gestures as a means of control for localizing three dimensional (3D) sound sources in a distributed immersive audio system. A prototype system was implemented and tested which uses state of the art technology to achieve the stated goals. A Windows Kinect is used for gesture recognition which translates human gestures into control messages by the prototype system, which in turn performs actions based on the recognized gestures. The term distributed in the context of this system refers to the audio processing capacity. The prototype system partitions and allocates the processing load between a number of endpoints. The reallocated processing load consists of the mixing of audio samples according to a specification. The endpoints used in this research are XMOS AVB endpoints. The firmware on these endpoints were modified to include the audio mixing capability which was controlled by a state of the art audio distribution networking standard, Ethernet AVB. The hardware used for the implementation of the prototype system is relatively cost efficient in comparison to professional audio hardware, and is also commercially available for end users. the successful implementation and results from user testing of the prototype system demonstrates how it is a feasible option for recording the localization of a sound source. The ability to partition the processing provides a modular approach to building immersive sound systems. This removes the constraint of a centralized mixing console with a predetermined speaker configuration.

The thesis deal with the design and construction of single cluster of apparatus which can serve as a signal source for wavefield synthesis. Apparatus can be controlled remotely by Ethernet interface. Thesis contains theoretical analyses of speaker system, class D amplifier, digital to analog conversion, digital format of acoustic data ADAT and Ethernet interface. Conceptual design of cluster and description of constructed module is concerned.

Binaural sound reproduction is most commonly made with headphones, although little research has been dedicated towards evaluating the sound of binaural for headphones reproduced on loudspeakers, which is the purpose of this thesis. An experimental quantitative method was designed in order to measure the objective effect of binaural processing both on headphones and loudspeakers so that they could be compared. Sine sweeps covering the entire audible frequency spectrum were processed with an ambisonics spatializer at different azimuth and distance parameters and then downmixed to binaural. The same source signal was also panned with a traditional equal-power panning law. Both was played back through headphones and loudspeakers then recorded with a dummy head. The recordings were deconvolved into graphs displaying their frequency responses. The results show that binaural sound produce different spectral distortion depending on the panning position on both headphones and loudspeakers, although additional subjective evaluation such as listening tests are required to determine the actual usefulness of binaural sound through loudspeakers.

yes / Purpose Flicker-defined form (FDF) stimuli have recently been adopted for visual field testing. A key difference between FDF and traditional perimetric stimuli is that the entire display background contains flickering dots. The purpose of this study was to determine whether the perception of FDF stimuli is influenced by lateral interactions involving regions beyond the stimulus border in young healthy observers. Methods Experiment 1 measured the effect of surround size and retinal eccentricity on the detection of the FDF contour. Psychometric functions were collected for surround diameters of 20°, 30° and 40°, and with stimuli centred at eccentricities of 0°, 10° and 20°. Experiment 2 measured the effect of target-surround temporal phase difference on apparent temporal contrast (flicker strength) of the target for both the FDF stimulus and a solid-field stimulus. Psychometric functions were collected for target-surround phase differences of 0°, 45°, 90°, 135° and 180°. Results Our results show a mild surround-suppression effect for FDF stimuli that is independent of surround size. Magnitudes of FDF surround suppression were consistent with the reduced temporal contrast energy of the stimulus compared to solid-field stimuli. Conclusion FDF stimuli necessarily have both flickering target and background. Our results suggest that visual field defects outside the target are unlikely to markedly influence the detection and perception of the FDF stimulus. Nevertheless, mild surround suppression of contrast arises for FDF stimuli, hence interactions between the background and the target area may influence FDF results in conditions that alter centre-surround perceptual effects.

The research discussed here examines how normal healthy aging affects spatial suppressive mechanisms in a variety of visual tasks using both static and dynamic stimuli. Prior research has suggested that younger adults demonstrate a center-surround antagonistic pattern in which they show spatial summation at low contrast and spatial suppression at high contrast in brief motion direction discrimination tasks. Older adults have been shown to have reduced spatial suppression at high contrast and this is thought to be related to reduced GABAergic inhibition in the visual cortex. The results obtained from this program of research suggest that age-related changes in optical and neural visual mechanisms do not affect spatiotemporal mechanisms for static stimuli when the target is presented with the mask (embedded masking). However, when the mask appears immediately before (forward masking) or after (backward masking) the target, older adults require more contrast to detect the target (Chapter 2). In addition, spatial suppression is not reduced for older adults in a task with moving stimuli presented at long durations, even with increasing speed (Chapter 3). In Chapter 4, we used static stimuli presented at brief durations to induce a sudden motion onset and found that although there was no significant age difference in spatial suppression, there was a trend showing reduced levels of spatial suppression in older adults. These results taken together suggest that inhibitory neural mechanisms in the visual cortex may mediate spatial suppression for briefly presented stimuli only. / Thesis / Doctor of Philosophy (PhD)

No description available.

Mit der Verbreitung von Linux als Desktopsystem steigen auch die Anforderungen des Nutzers an multimediale Fähigkeiten wie z.B. das Anhören eines digitalisierten Musikstückes, die Einbindung einer Digitalkamera in die Bildverarbeitung, die Nutzung einer Radio/TV-Karte oder gar das Bearbeiten eines kleinen Videofilms.

No description available.

Virtual three-dimensional auditory displays (V3DADs) use digital signal processing to deliver sounds (typically through headphones) that seem to originate from specific external spatial locations. This set of studies investigates the delivery of V3DADs through bone-conduction transducers (BCTs) in addition to conventional headphones. Although previous research has shown that spatial separation can be induced through BCTs, some additional signal adjustments are required for optimization of V3DADs, due to the difference in hearing pathways. The present studies tested a bone-conduction adjustment function (BAF) derived from equal-loudness judgments on pure tones whose frequencies were spaced one critical band apart. Localization performance was assessed through conventional air-conduction headphones, BCTs with only transducer correction, and BCTs with a BAF. The results showed that in the elevation plane, the BAF was effective in restoring the spectral cues altered by the bone-conduction pathway. No evidence for increased percept variability or decreased lateralization in the bone-conduction conditions was found. These findings indicate that a V3DAD can be implemented on a BCT and that a BAF will improve performance, but that there is an apparent performance cost that cannot be addressed with BAFs measured using the methodology in the present studies.