Automatic text-independent pronunciation scoring of foreign language student speech

SRI International is currently involved in the development of a new generation of software systems for automatic scoring of pronunciation as part of the Voice Interactive Language Training System (VILTS) project. This paper describes the goals of the VILTS system, the speech corpus and the algorithm development. The automatic grading system uses SRI's Decipher/sup TM/ continuous speech recognition system to generate phonetic segmentations that are used to produce pronunciation scores at the end of each lesson. The scores produced by the system are similar to those of expert human listeners. Unlike previous approaches, in which models were built for specific sentences or phrases, we present a new family of algorithms designed to perform well even when knowledge of the exact text to be used is not available.