The Importance of Lexical Tone for Sentence Understanding: Utilizing Functional Load Principle to Simulate Comprehension Process

The missing information of lexical tone of Chinese has been proved to have no inhibitory effect on understanding in quiet environment in previous study. The current study set out to examine the importance of tone for speech comprehension when the contextual information is incomplete. The first experiment examined the correlation between second language (L2) speech comprehensibility and tone error ratio through 180 L2 speech samples with severe segmental and suprasegmental errors. The second experiment investigated the correlation between functional load of missing tone and word choices of sentences with tone-caused ambiguity pinyin sequences without tone information, and 30 native Mandarin speakers were asked to dictate the 14 ambiguous level-tone sentences. The results showed that tone error ratio strongly correlated with comprehensibility, and the word choice is also significantly correlated with the FL of the tones, suggesting that tone is not a redundant information in communication, and its ambiguity resolution function can be measured through FL model.