Overlap behaviour in task-oriented dialogue

Speakers change the way they speak depending on the surrounding environment. When masking noise obstructs the communication channel between interlocutors, they consistently engage in Lombard speech, whose spectral characteristics are well described (e.g. [1, 2, 3]) and are believed to result in better intelligibility through energetic masking reduction (e.g. [4]). However, less is known about how speakers adapt to the temporal characteristics of a fluctuating masker, and whether any such changes aid communication. In this study pairs of speakers were recorded while engaged in a sudoku-solving task in quiet and in several masking conditions. Maskers were either a competing talker or speech modulated noise with identical temporal characteristics, chosen to investigate the informational masking potential of the masker. The silence density of each masker was also manipulated by adjusting the durations of pauses in the masker to 33% or 66% of the overall duration of the masker. In all masking conditions, speakers displayed a reduction of overlap with the masker relative to a baseline computed from the masker and speech produced in quiet (Figure 1). The overlap reduction tended to be larger for less