What User Interface to Use for Virtual Reality? 2D, 3D or Speech-A User Study

In virtual reality different demands on the user interface have to be addressed than on classic screen applications. That's why established strategies from other digital media cannot be transferred unreflected and at least adaptation is required. So one of the leading questions is: which form of interface is preferable for virtual reality? Are 2D interfaces that are mostly used in combination with mouse or touch interactions the means of choice, although they do not use the medium's full capabilities? What about 3D interfaces that can be naturally integrated into the virtual space? And last but not least: are speech interfaces, the fastest and most natural form of human interaction/communication, which have recently established themselves in other areas (e.g. digital assistants), ready to conquer the world of virtual reality? To answer these question this work compares these three approaches based on a quantitative user study and highlights advantages and disadvantages of the respective interfaces for virtual reality applications.