Method and apparatus for hierarchical training of speech models for use in speaker verification

A method and apparatus for generating a pair of data elements is provided suitable for use in a speaker verification system. The pair includes a first element representative of a speaker independent template and a second element representative of an extended speaker specific speech pattern. An audio signal forming enrollment data associated with a given speaker is received and processed to derive a speaker independent template and a speaker specific speech pattern. The speaker specific speech pattern is then processed to derive an extended speaker specific speech pattern. The extended speaker specific speech pattern includes a set of expanded speech models, each expanded speech model including a plurality of groups of states, the groups of states being linked to one another by inter-group transitions. Optionally, the expanded speech models are processed on the basis of the enrollment data to condition at least one of the plurality of inter-group transitions.