1. A method for speaker diarization, comprising: dividing a speech session into segments of duration less than an average duration between speaker change; parameterizing each segment by a time dependent probability density function supervector; computing a difference between successive segment supervectors; and computing a scatter measure of the difference as an estimate of intra-speaker variability; wherein said steps are implemented in either: computer hardware configured to perform said identifying, tracing, and providing steps, or computer software embodied in a non-transitory, tangible, computer-readable storage medium.