Sebastian Moeller

Audio and video channel impact on perceived audio-visual quality in different interactive contexts

With the advent of audio-visual IP clients, video telephony becomes a realistic option in many application scenarios. In order to guarantee an adequate quality to its users, providers of audio-visual telephony services need to know the impact of the audio and video transmission channel characteristics on perceived Quality of Experience (QoE) in a realistic interactive setting. For this aim, a conversational video telephony experiment was conducted where the audio and video channel settings were adjusted in a controlled way, and participants were asked about the perceived audio, video and overall quality after carrying out a conversation over the audio-visual channel. We analyze the results with respect to the impact the two modalities have, as well as with respect to the impact of the conversation scenario.

Security and usability research using a microworld environment

Technological developments and the addition of new features to existing applications or services require the inclusion of security mechanisms to protect the user. When using these mechanisms the user faces a tradeoff between more risky and more efficient or safer and less efficient use of the system. We discuss this tradeoff and present a novel complementary experimental system which provides researchers and corporations the ability to explore and model the usability and security tradeoff in the context of user interaction with security systems and psychological acceptability, even before the actual development and implementation processes have ended.