6. A method of identifying a source of data input to a computing system using prosodic elements of speech comprising: a) presenting a challenge item to an entity, which challenge item is associated with a reference set of words and associated prosodic characteristics; b) receiving speech utterance from an entity related to said challenge item; wherein said reference set of words represents a selected set of one or more contiguous words which when vocalized have a measurable difference in prosodic characteristics between a reference human voice and a reference computer synthesized voice that exceeds a target threshold; c) processing said speech utterance with said computing system to compute first prosodic characteristics of said entity; d) generating a determination of whether said speech utterance originated from a machine or a human based on step (c).
6. A method of identifying a source of data input to a computing system using prosodic elements of speech comprising: a) presenting a challenge item to an entity, which challenge item is associated with a reference set of words and associated prosodic characteristics; b) receiving speech utterance from an entity related to said challenge item; wherein said reference set of words represents a selected set of one or more contiguous words which when vocalized have a measurable difference in prosodic characteristics between a reference human voice and a reference computer synthesized voice that exceeds a target threshold; c) processing said speech utterance with said computing system to compute first prosodic characteristics of said entity; d) generating a determination of whether said speech utterance originated from a machine or a human based on step (c). 7. The method of claim 6 further including the steps: estimating a first computer synthesized voice that best correlates to said entity; and selecting said challenge item based on an identity of said first entity so as to maximize a difference in prosodic characteristics.