1. A method, comprising: using an audio pick up device to capture a speech sample from a claimant claiming an identity; and using computer software embodied on a computer readable medium to perform the following steps: calculating a ratio of unvoiced frames to a total number of frames in the speech sample, determining an equal error rate value corresponding to the speech sample based on the calculated ratio, comparing the determined equal error rate value corresponding to the speech sample to an equal error rate value associated with the claimed identity to select a decision threshold, generating a match score based on a comparison of the speech sample to a voice sample associated with the claimed identity, and deciding whether to accept the identity claim of the claimant based on a comparison of the match score to the decision threshold.