15. A computer-readable storage device having instructions stored which, when executed by a computing device, result in the computing device performing operations comprising: receiving, from a user of a speech verification system, a plurality of speech samples of a same word, wherein the plurality of speech samples of the same word comprise: a current speech response; and a plurality of previously recorded speech samples, wherein each of the previously recorded speech samples is associated with a distinct location; generating a sample similarity from the plurality of speech samples; making a decision whether to enroll the user in the speech verification system according to a comparison of the sample similarity with a threshold, wherein the decision is a first decision if the sample similarity is above the threshold and the decision is a second decision different from and mutually exclusive with the first decision if the sample similarity is below the threshold; and enrolling the user in the speech verification system responsively to the decision's being the second decision.
16. The computer-readable storage device of claim 15 , wherein the sample similarity has a range which varies based on a job title of the user.