Improved automatic recognition of Norwegian natural numbers by incorporating phonetic knowledge

This paper addresses the problem of speaker-independent connected natural number recognition over telephone lines. Increasing the vocabulary from digits (0-9) to natural numbers (0-99) opens for more user-friendly services, but also introduces many new, language-specific problems, such as more similar sounding words, a more complex grammar network, and more ambiguities due to segmentation problems of connected natural numbers. The paper shows that incorporating phonetic knowledge into a Norwegian natural number recogniser, improved the recognition performance from 70.6% to 76.3% correctly recognised 8-digit telephone numbers in noisy conditions