This paper describes the development, implementation and validation of an automatic speaker recognition system on an iPad tablet. A score normalization approach, referred as Nearest Neighbor Normalization (3N), is applied in order to improve the baseline speaker verification system. The system is evaluated on the MOBIO corpus and results show an absolute improvement of the HTER by more than 4% when the score normalization is performed. A human-centered interface is implemented for the speaker recognition system and a survey is collected from 28 users in order to evaluate the application. The results showed that the users, familiar with touchscreen interface, found the application easy to learn and use