A confidence based tree structured decoder for private automatic branch exchange

A high performance voice controlled private automatic branch exchange (PABX) is difficult to achieve, especially when users are not required to follow a rigid speaking format. By incorporating hierarchical confidence measures into a tree structured PABX decoder, the keyword accuracy is increased from 89.86% to 92.63%. Further improvement is made by a confidence measure based postprocessor, which rejects 5.68% of all testing utterances and improves the accuracy to 97.18%.