TY  - THES
A1  - Kretzer, Katharina
T1  - Einfluss der Form elektrischer Impulse auf die intracochleäre neuronale Antwort bei Cochlea-Implantat-Trägern: triphasische Pulse mit anodischer und kathodischer zweiter Phase
T1  - Influence of the shape of electrical pulses on the intracochlear neural response in cochlear implant recipients: triphasic pulses with anodic and cathodic second phase
N2  - Vorliegende Arbeit beschäftigte sich mit der Verbesserung von Defiziten der elektrischen Stimulation durch Cochlea Implantate (CI) mit alternativen Pulsformen. Dabei wurde mit elektrophysiologischen und psychophysikalischen Methoden untersucht, wie sich die Pulsformen auf die Effektivität der Stimulation auswirken. Es wurden präzisions-triphasische Pulse (pTP) mit anodischer und kathodischer zweiter Phase anhand der Daten von elf Probanden untersucht.
Im Rahmen der objektiven elektrophysiologischen Messung wurde mit den unterschiedlichen Formen des pTP an drei unterschiedlichen Kontaktpositionen auf den CI-Elektrodenträgern stimuliert, und die Stärke der jeweils evozierten neuronalen Antwort aufgezeichnet. Der subjektive psychophysikalische Test diente dazu, die pulsformspezifischen Hörschwellen zu bestimmen und wurde an zwei unterschiedlichen Kontakten auf den CI-Elektrodenträgern durchgeführt. 
Dabei erzielten pTP, welche eine symmetrisch-triphasische Pulsform aufwiesen, geringere neuronale Antwortstärken und höhere Hörschwellen als die pTP, die einer biphasischen Pulsform glichen. Diejenigen pTP, die biphasischen Pulsen mit anodischer erster Phase glichen, erzielten dabei die höchsten neuronalen Antwortstärken und die niedrigsten Hörschwellen.
N2  - Present work dealt with the improvement of deficits of electrical stimulation by cochlear implants (CI) by means of alternative pulse shapes. This involved the use of electrophysiological und psychophysical methods to investigate the effect of pulse shape on the effectiveness of stimulation. Precision-triphasic pulses (pTP) with anodic and cathodic second phase were examined using data from eleven subjects. 
In the objective electrophysiological measurement, the different shapes of the pTP were stimulated from three different contact positions on the CI electrode arrays and the strength of the neural response evoked in each case was recorded. In the subjective psychophysical test, pTP stimulation was performed from two different contact positions on the CI electrode arrays and the pulse shape-specific detection thresholds were compared.
The results showed that pTP, which exhibited a symmetric-triphasic pulse shape, achieved lower neuronal response strengths and higher detection thresholds than pTP that resembled a biphasic pulse shape. Those pTP, that resembled biphasic pulses with an anodic first phase, achieved the highest neuronal response strengths and the lowest detection thresholds.
KW  - Cochlear-Implantat
KW  - Elektrophysiologie
KW  - Psychophysik
KW  - elektrische Stimulation
KW  - cochlear implant
KW  - electrical stimulation
KW  - psychophysics
KW  - electrophysiology
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-281650
ER  - 
TY  - JOUR
A1  - Muth, Felicitas V.
A1  - Heilig, Michael
A1  - Marquardt, Dorothea
A1  - Mittelberg, Linda
A1  - Sebald, Albrecht
A1  - Kunde, Wilfried
T1  - Lightness perception of structured surfaces
JF  - Color Research and Application
N2  - Visual perception of surfaces is of utmost importance in everyday life. Therefore, it comes naturally, that different surface structures evoke different visual impressions in the viewer even if the material underlying these surface structures is the same. This topic is especially virulent for manufacturing processes in which more than one stakeholder is involved, but where the final product needs to meet certain criteria. A common practice to address such slight but perceivable differences in the visual appearance of structured surfaces is that trained evaluators assess the samples and assign a pass or fail. However, this process is both time consuming and cost intensive. Thus, we conducted two studies to analyze the relationship between physical surface structure parameters and participants visual assessment of the samples. With the first experiment, we aimed at uncovering a relationship between physical roughness parameters and visual lightness perception while the second experiment was designed to test participants' discrimination sensitivity across the range of stimuli. Perceived lightness and the measured surface roughness were nonlinearly related to the surface structure. Additionally, we found a linear relationship between the engraving parameter and physical brightness. Surface structure was an ideal predictor for perceived lightness and participants discriminated equally well across the entire range of surface structures.
KW  - surface structure
KW  - appearance
KW  - color perception
KW  - maximum likelihood difference scaling
KW  - psychophysics
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257314
VL  - 47
IS  - 2
ER  -