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TU Berlin

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Dr.-Ing. Friedemann Köster


Research Field
- Quality of Speech and Audio
- Speech- and Signal Processing 

Research Topics
- Multidimensional Diagnostic Analysis of Conversational Speech Quality

Friedemann Köster studied Industrial Engineering at the Christian-Albrechts-University of Kiel. In 2012 he finished his studies and received his Dipl.-Wirtsch.-Ing. degree. Currently he is working as a research assistant at the Quality and Usability Lab of Deutsche Telekom Laboratories, TU-Berlin, where he also works towards a Phd degree in the field of quality.



Speech Communication

Quality and Usability Lab
Deutsche Telekom Laboratories
TU Berlin
Ernst-Reuter-Platz 7
D-10587 Berlin, Germany


+49 30 8353 58255
+49 151 14745202


Changes of vigilance caused by varying bit rate conditions
Zitatschlüssel antons2013c
Autor Antons, Jan-Niklas and Köster, Friedemann and Arndt, Sebastian and Möller, Sebastian and Schleicher, Robert
Buchtitel 2013 Fifth International Workshop on Quality of Multimedia Experience (QoMEX)
Seiten 148–151
Jahr 2013
DOI 10.1109/QoMEX.2013.6603228
Workshop Workshop
Ort Klagenfurt am Wörthersee, Austria
Adresse Piscataway, NJ, USA
Monat jul
Notiz Electronic/online
Verlag IEEE
Serie QoMEX
Wie herausgegeben Full
Zusammenfassung Quality aspects of media content are usually assessed by using subjective rating methods where subjects provide active feedback towards the perceived quality. The process how this judgment is being formed and the long-term influences of accompanying physiological processes are not represented by these methods. In this paper we used the electroencephalogram (EEG) to assess the cognitive state (vigilance) of listeners measured by the alpha frequency band power with respect to varying bit rate conditions. We show that stimuli with varying and constant bit rate cause a state of reduced vigilance. In addition we show the potential tendency that an interval of high bit rate audio inserted into a low bit rate stimulus increased the vigilance of listeners at the timescale of minutes. The results show that the perception of degraded media has long-term influences on physiological processes at the time scale of minutes which may influence customer behavior even though it probably stays undetected using purely standard subjective test methods.
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