Thresholds of formant discrimination of speech and non-speech sounds were compared for native listeners of English and Chinese. English listeners showed significantly better thresholds than Chinese listeners, not only for English vowels, but also for Chinese vowels. Thresholds for vowel-spectrum-shaped noise were comparable for the two groups. These results suggest that English listeners are more sensitive to formant frequency changes of vowel stimuli than Chinese listeners, possibly due to the denser vowel space for English than for Mandarin Chinese. However, the psychophysical capacity to discriminate formant frequency changes in non-speech sounds is similar for English and Chinese listeners.