The effect of soft, modal and loud voice levels on entrainment in noisy conditions
Éva Székely, Mark T. Keane, Julie Carson-Berndsen · 2015
Conversation partners have a tendency to adapt their vocal in- tensity to each other and to other social and environmental fac- tors. A socially adequate vocal intensity level by a speech syn- thesiser that goes beyond mere volume adjustment is highly de- sirable for a rewarding and successful human-machine or ma- chine mediated human-human interaction. This paper examines the interaction of the Lombard effect and speaker entrainment in a controlled experiment conducted with a confederate inter- locutor. The interlocutor was asked to maintain either a soft, a modal or a loud voice level during the dialogues. Through half of the trials, subjects were exposed to a cocktail party noise through headphones. The analytical results suggest that both the background noise and the interlocutor’s voice level affect the dynamics of speaker entrainment. Speakers appear to still en- train to the voice level of their interlocutor in noisy conditions, though to a lesser extent, as strategies of ensuring intelligibility affect voice levels as well. These findings could be leveraged in spoken dialogue systems and speech generating devices to help choose a vocal effort level for the synthetic voice that is both intelligible and socially suited to a specific interaction.