Voice source parameters for speaker verification

In this paper we report on a study of the variability of voice source parameters in the context of speaker characterisation, and we propose a speaker verification system which incorporates these parameters. The motivation for this approach is that, whilst we have conscious control over the action of our vocal tract articulators such as the tongue and jaw, we have only limited voluntary muscle control over the vocal cords. The conjecture is, therefore, that impostors are less likely to be able to mimic vocal cord effects than vocal tract effects. The hybrid speaker verification system that is proposed incorporates two sub-systems to improve the overall performance: (i) a cepstral-based HMM with cohort normalisation and (ii) voice source parameters derived from Multi-cycle Closed-phase Glottal Inverse Filtering (MCGIF). Preliminary experimental results show that the hybrid system performs better than either of the sub-systems in terms of the equal error rate (EER). Specifically, the hybrid system improved the performance of the cepstral-based HMM system by 78% on average, resulting in a mean EER of 0.42% for the specific tests conducted.