Abstract
Voice assistants (VA) are an emerging technology that have become an essential tool of the twenty-first century. The VA ease of access and use has resulted in high usability curiosity in voice assistants. Usability is an essential aspect of any emerging technology, with every technology having a standardized usability measure. Despite the high acceptance rate on the use of VA, to the best of our knowledge, not many studies were carried out on voice assistants' usability. We reviewed studies that used voice assistants for various tasks in this context. Our study highlighted the usability measures currently used for voice assistants. Moreover, our study also highlighted the independent variables used and their context of use. We employed the ISO 9241-11 framework as the measuring tool in our study. We highlighted voice assistant's usability measures currently used; both within the ISO 9241-11 framework, as well as outside of it to provide a comprehensive view. A range of diverse independent variables are identified that were used to measure usability. We also specified that the independent variables still not used to measure some usability experience. We currently concluded what was carried out on voice assistant usability measurement and what research gaps were present. We also examined if the ISO 9241-11 framework can be used as a standard measurement tool for voice assistants.