The Teleprasenz Consortium: Structure and intentions

The Teleprasenz-Consortium is an open group of currently 37 scientists of different disciplines who devote a major part of their research activities to the foundations of telepresence technology. Telepresence technology is basically understood as a means to bridge spatial and temporal gaps as well as certain kinds of concealment, inaccessibility and danger of exposure. The activities of the consortium are organized into three main branches: virtual environment, surveillance and control systems, and speech and language technology. A brief summary of the main activities in these areas is given

The Reduction of Vertical Interchannel Crosstalk: The Analysis of Localisation Thresholds for Natural Sound Sources

In subjective listening tests, natural sound sources were presented to subjects as vertically-oriented phantom images from two layers of loudspeakers, ‘height’ and ‘main’. Subjects were required to reduce the amplitude of the height layer until the position of the resultant sound source matched that of the same source presented from the main layer only (the localisation threshold). Delays of 0, 1 and 10 ms were applied to the height layer with respect to the main, with vertical stereophonic and quadraphonic conditions being tested. The results of the study showed that the localisation thresholds obtained were not significantly affected by sound source or presentation method. Instead, the only variable whose effect was significant was interchannel time difference (ICTD). For ICTD of 0 ms, the median threshold was −9.5 dB, which was significantly lower than the −7 dB found for both 1 and 10 ms. The results of the study have implications both for the recording of sound sources for three-dimensional (3D) audio reproduction formats and also for the rendering of 3D images

A Comparison between Horizontal and Vertical Interchannel Decorrelation

The perceptual effects of interchannel decorrelation on perceived image spread have been investigated subjectively in both horizontal and vertical stereophonic reproductions, looking specifically at the frequency dependency of decorrelation. Fourteen and thirteen subjects graded the horizontal and vertical image spreads of a pink noise sample, respectively. The pink noise signal had been decorrelated by a complementary comb-filter decorrelation algorithm, varying the frequency-band, time-delay and decorrelation factor for each sample. Results generally indicated that interchannel decorrelation had a significant effect on auditory image spread both horizontally and vertically, with spread increasing as correlation decreases. However, it was found that the effect of vertical decorrelation was less effective than that of horizontal decorrelation. The results also suggest that the decorrelation effect was frequency-dependent; changes in horizontal image spread were more apparent in the high frequency band, whereas those in vertical image spread were in the low band. Furthermore, objective analysis suggests that the perception of vertical image spread for the low and middle frequency bands could be associated with a floor reflection; whereas for the high band, the results appear to be related to spectral notches in the ear input signals

Binaural room simulation

In every-day listening the auditory event perceived by a listener is determined not only by the sound signal that a sound emits but also by a variety of environmental parameters. These parameters are the position, orientation and directional characteristics of the sound source, the listener's position and orientation, the geometrical and acoustical properties of surfaces which affect the sound field and the sound propagation properties of the surrounding fluid. A complete set of these parameters can be called an Acoustic Environment. If the auditory event perceived by a listener is manipulated in such a way that the listener is shifted acoustically into a different acoustic environment without moving himself physically, a Virtual Acoustic Environment has been created. Here, we deal with a special technique to set up nearly arbitrary Virtual Acoustic Environments, the Binaural Room Simulation. The purpose of the Binaural Room Simulation is to compute the binaural impulse response related to a virtual acoustic environment taking into account all parameters mentioned above. One possible way to describe a Virtual Acoustic Environment is the concept of the virtual sound sources. Each of the virtual sources emits a certain signal which is correlated but not necessarily identical with the signal emitted by the direct sound source. If source and receiver are non moving, the acoustic environment becomes a linear time-invariant system. Then, the Binaural Impulse Response from the source to a listener' s eardrums contains all relevant auditory information related to the Virtual Acoustic Environment. Listening into the simulated environment can easily be achieved by convolving the Binaural Impulse Response with dry signals and representing the results via headphones

Investigating biofilm deformation using optical coherence tomography and fluid-structure interaction simulation

Das Feld der Biofilmmechanik ist noch immer einer der am wenigsten untersuchten Bereiche der Biofilmforschung. Um zu verstehen, was Biofilmen eine so große Widerstandskraft gegen Scherspannung verleiht, muss das Wechselspiel von Deformation und Änderung der Biofilmmatrix im Detail untersucht werden. Seit der Einordnung von Biofilmen in viskoelastische Materialien wurden fast keine Untersuchungen hinsichtlich elastischer Deformation durchgeführt. Jedoch sind es die elastischen Eigenschaften eines Biofilms, welche der Biofilmmatrix die Fähigkeit zur Absorption von mechanischem Stress maßgeblich beeinflussen. Diese Dissertation vertieft das Verständnis im Bereich der elastischen Biofilmmechanik. Durch die Nutzung der optischen Kohärenztomographie (OCT) konnten neue Erkenntnisse über die Dynamik der elastischen Biofilmdeformation gewonnen werden. Das beinhaltet die Änderung der Porosität während des Deformationsprozesses, die Änderung der mechanischen Eigenschaften mit der Fließgeschwindigkeit während der Kultivierung, sowie die Bestimmung zuvor noch nicht gemessener mechanischer Parameter wie die Poissonzahl, das Kompressionsmodul, sowie die Kompressibilität von Biofilmen. Zum ersten Mal konnte eine Messgröße für die Poissonzahl bestimmt werden, welche die relative Längenänderung zwischen transversaler und axialer Deformation beschreibt. Da Biofilme einen hohen Wassergehalt haben, wurde lange Zeit angenommen, dass sie sich wie inkompressible Materialien (z.B. Gummi) verhalten. Daher wurden in Simulationsstudien immer positive Werte für die Poissonzahl angenommen. OCT Aufnahmen während Deformationsexperimente zeigten jedoch eine höchst kompressible Biofilmmatrix. Daraus wurde geschlossen, dass es sich bei den untersuchten Biofilmen zum Teil um sogenannte auxetische Materialien mit negativer Poissonzahl handelt. Dies ändert das Verständnis der mechanischen Natur von Biofilmen maßgeblich. Die daraus ermittelten Werte erlaubten zudem die Bestimmung des Kompressionsmoduls, sowie der Kompressibilität. In Fluid-Struktur-Interaktions Simulationen wurden die gewonnenen Parameter daher genutzt, um das mechanische Verständnis von Biofilmen im Detail zu verstehen. Biofilmdeformationen, welche mittels OCT verfolgt wurden, lieferten reale Geometrien, die als strukturelle Vorlage für die Simulationen dienten. Durch die Implementierung von realen Geometrien konnte die Abschätzung von Materialkonstanten weiter verbessert werden. Mit diesen Simulationen konnte gezeigt werden, dass der Young\u27s Modulus bei ansteigender Schubspannung nicht konstant bleibt. Dies ist eine direkte Konsequenz der Heterogenität der Biofilmstruktur. Zuletzt wurde der Ein Fluss von negativen Poissonzahlen untersucht und die Qualität der Simulationen diskutiert. Biofilme zeigten in Simulationen mit negativen Poissonzahlen Deformationen, welche vergleichbar mit den realen OCT Aufnahmen waren. Die Simulationen zeigten, dass es sich bei Biofilmen teilweise um auxetische Materialien handelt

Crime and History – the German Workshop

As in other Western European countries, although with some delay, Crime and Criminal Justice History has become a distinctive sub-discipline of social history in Germany in the last few years. The first impulsion came from historical research on lower social strata and marginal groups, but also from the investigation of social unrest. This area soared in the seventies and eighties. A large number of scholars working in the field of crime and criminal justice history in Germany came to the sub..

Häusliche Gewalt gegen Frauen in Deutschland

Im vorliegenden Beitrag wird mithilfe von zwei deutschlandweit repräsentativen Dunkelfeldstudien ermittelt, inwiefern sich die Prävalenz häuslicher Gewalt gegen Frauen in Deutschland zwischen 1992 und 2011 verändert hat. Diese Angaben werden durch Daten zum individuellen Anzeigeverhalten ergänzt. Aus den Befunden lässt sich ein unmittelbarer Handlungsbedarf in Hinblick auf verstärkte Informationskampagnen zu den bestehenden Schutzmöglichkeiten vor häuslicher Gewalt ableiten. (Autorenreferat)Based on two representative victim surveys, the present article aims at clarifying how the prevalence of domestic violence against women in Germany has changed from 1992 to 2011. The results are complemented by data on domestic violence that were reported to the police. These findings are discussed with respect to practical implications. (author's abstract

Adjustment of interaural-time-difference analysis to sound level

To localize low-frequency sound sources in azimuth, the binaural system compares the timing of sound waves at the two ears with microsecond precision. A similarly high precision is also seen in the binaural processing of the envelopes of high-frequency complex sounds. Both for low- and high-frequency sounds, interaural time difference (ITD) acuity is to a large extent independent of sound level. The mechanisms underlying this level-invariant extraction of ITDs by the binaural system are, however, only poorly understood. We use high-frequency pip trains with asymmetric and dichotic pip envelopes in a combined psychophysical, electrophysiological, and modeling approach. Although the dichotic envelopes cannot be physically matched in terms of ITD, the match produced perceptually by humans is very reliable, and it depends systematically on the overall sound level. These data are reflected in neural responses from the gerbil lateral superior olive and lateral lemniscus. The results are predicted in an existing temporal-integration model extended with a level-dependent threshold criterion. These data provide a very sensitive quantification of how the peripheral temporal code is conditioned for binaural analysis