Investigating consonant reduction in Mandarin Chinese with improved forced alignment

Phonetic reduction has been an important topic in linguistics research. It also presents a great challenge for forced alignment, a technique widely used for automatic phonetic segmentation. In this study, we employed skip-state HMMs to improve forced alignment quality and to make forced alignment applicable to the investigation of phonetic reduction and deletion. With skip-state HMMs, forced alignment accuracy at 10 ms agreement was improved from 73.3% to 75.6% on a corpus of Mandarin Chinese broadcast news speech. Our analysis based on the improved forced alignment of Mandarin broadcast news speech – verified by hand segmentation of a random sample of cases – shows that: 1. The durations of frication and aspiration are additive in the production of plosives and affricates; 2. Plosives are more likely to be deleted than affricates; and 3. Plosives and affricates in higher-frequency words and at word-medial position are more likely to be reduced.