On interaction behaviour in telephone conversations under transmission delay

• Quality judgments on delayed telephone lines differ for different experiments.
• Conversational courses change with increasing delay.
• The realities of the two interlocutors diverge with increasing delay.
• Utterance pace decrease explains a significant amount of quality ratings.

This work analyses the interaction behaviour of two interlocutors communicating over telephone connections affected by echo-free delay, for conversation tasks yielding different speed and structure. Based on a series of conversation tests, it is shown that transmission delay in a telephone circuit does not only result in a longer time until information is exchanged between the interlocutors, but also alters various characteristics of the conversational course. It was observed that with increasing transmission delay, the realities perceived by the interlocutors increasingly diverge. As a measure of utterance pace, a new conversation surface structure metric, the so-called utterance rhythm (URY), is introduced. Using surface-structure analysis of conversations from different conversation tests, it is shown that peoples’ utterance rhythm stays rather constant in close-to-natural conversations, but is considerably affected for scenarios requiring fast interaction and a clear answering structure. At the same time, the quality of the connection is perceived less critically in close-to-natural than in tasks requiring fast interaction, that is, interactive tasks leading to a delay-dependant utterance rhythm. Hence, the conclusion can be drawn that the degree of necessary adaption of the utterance rhythm to a certain delay condition co-determines the extent to which transmission delay impacts the perceived integral quality of a call.