1. A biometric speaker-identification apparatus that generates one or more speaker-identity candidates for a speaker based on probe match scores obtained by performing a voice matching operation between a probe and templates in a biometric corpus, comprising: a plurality of prototypes; and a speaker-identification processor coupled to the biometric corpus, the speaker-identification processor configured to select templates of the biometric corpus as the speaker-identity candidates based on the prototypes, wherein the speaker-identification processor is further configured to: perform the voice matching operation between the speaker-identity candidates and the templates in the biometric corpus to obtain one or more speaker-identity-candidate match scores; perform a similarity measurement between the speaker-identity-candidate match scores and the probe match scores to obtain one or more similarity values; and order the speaker-identity candidates based on the similarity values, and wherein the similarity measurement for an i th speaker-identity candidate is a dot product defined as: 
 DOT i =SUM(tms it *pms t ), where the sum is taken over all the templates in the biometric corpus, tms it is a template match score between the i th speaker-identity candidate and a t th template, and pms t is a probe match score for the t th template.