Perceptual contribution of vowel sub-segments to Mandarin tone identification

Abstract

Recent noise-replacement studies showed that (1) vowels carried more intelligibility information in Mandarin sentence recognition, and (2) a little vowel onset portion could significantly increase the intelligibility when it was added to the consonant-only Mandarin sentences. This study further evaluated the perceptual contribution of vowel sub-segments to Mandarin tone identification. The original duration-normalized vowels (FULL) were modified to produce two types of stimulus, i.e., (1) Left-only [LO (p)], which preserved p = 10% to 50% of the initial vowel portion, and replaced the rest vowel portion with speech-shaped noise (SSN), and (2) center-only [CO (p)], which preserved p = 15% to 60% of the center vowel portion, and replaced the rest initial and final vowel portions with SSN. Tone identification scores were collected from 20 normal-hearing native-Mandarin listeners. Results in the present study showed that (1) Mandarin tone perception at the LO (10%) condition was slightly higher than the chance level (i.e., 25%); (2) tone identification at the CO (60%) condition was not significantly different with that at the FULL condition. These findings suggest that vowel onset portion provides information redundant to vowel centers for Mandarin tone identification, and vowel centers contain sufficient information for reliable Mandarin tone identification.