1. A method of controlling access to a computing system comprising: selecting first test text data to be articulated as a first speech utterance by a first entity providing input to the computing system based on measurable differences in articulation between a human speaker and a machine for the first test text data exceeding a target threshold; storing a voice print for the first entity at the computing system based on said first speech utterance being converted into recognized speech data; wherein said first entity can include either a human or a computer using a synthesized voice; receiving a second speech utterance by a second entity; processing said second recognized speech data with said computing system to determine whether said second speech utterance also originated from said first entity; and controlling whether said second entity is allowed to access an account and/or data based on comparing said voice print to said second recognized speech data.