Modeling the rate of speech by Markov processes on curves
We propose a statistical model for automatic speech recognition that relates variations in speaking rate to nonlinear warpings of time. The model describes a discrete random variable, s(t), that evolves as a function of the arc length traversed along a curve, parameterized by x(t). Since arc length does not depend on the rate at which a curve is traversed, this evolution gives rise to a family of Markov processes whose predictions, Pr[sjx], are invariant to nonlinear warpings of time. We describe the use of such models, known as Markov processes on curves (MPCs), for automatic speech recognition, where x are acoustic feature trajectories and s are phonetic transcriptions. On two tasks|recognizing New Jersey town names and connected alpha-digits|we nd that MPCs yield lower word error rates than comparably trained hid-