Detection thresholds of Chinese vowels, Korean vowels, and a complex tone, with harmonic and noise carriers were measured in noise for Mandarin Chinese-native listeners. The harmonic index was calculated as the difference between detection thresholds of the stimuli with harmonic carriers and those with noise carriers. The harmonic index for Chinese vowels was significantly greater than that for Korean vowels and the complex tone. Moreover, native speech sounds were rated significantly more native-like than non-native speech and non-speech sounds. The results indicate that native speech has an advantage over other sounds in simple auditory tasks like sound detection.