High levels of automation in future aviation technologies such as Unmanned Aircraft Systems could lead to human operators losing essential Situation Awareness and becoming 'out-of-the-loop'. Research into Human Autonomy Teaming proposes that improved communication between the human and autonomous agents of a system can address this problem. However, knowledge around the effect of automation audio communication is lacking in the literature and we propose audio-voice conversation would provide the optimum form of communication. In this study we evaluated the impact that providing a conversational interface to a synthetic teammate had on the performance, Situation Awareness and perception of teaming of the human teammate. Twenty-four participants conducted experimental trials on a computer-based task adapted from a Levels Of Automation test method developed by Endsley and Kaber (1999). The results show that synthetic voice communication had a significant positive effect on human performance and perception of teaming. Also demonstrated was that teaming structure has an effect on how that performance increases, with participants in higher Levels Of Automation where the automation provides decision making advice demonstrating a habit of consistently following voice provided advice, even when that advice results in the participant adopting new behaviours and taking more risks.