Vowel formant discrimination: Effects of listeners’ hearing status and language background

Abstract

The goal of this study was to examine effects of listeners’ hearing status (e.g., normal and impaired hearing) and language background (e.g., native and non-native) on vowel formant discrimination. Thresholds of formant discrimination were measured for F1 and F2 of English vowels at 70 dB SPL for normal- (NH) and impaired-hearing (HI) listeners using a three-interval, two-alternative forced-choice procedure with a two-down, one-up tracking algorithm. Formant thresholds of HI listeners were comparable to those of NH listeners for F1, but significantly higher than NH listeners for F2. Results of a further experiment indicated that an amplification of the F2 peak could markedly improve formant discrimination for HI listeners, but a simple amplification of the sound level did not provide any benefit to them. On the other hand, another experiment showed that vowel density of listeners’ native language appeared to affect vowel formant discrimination, i.e., more crowded vowel space of listeners’ native language, better their vowel formant discrimination. For example, English-native listeners showed significantly lower thresholds of formant discrimination for both English and Chinese vowels than Chinese-native listeners. However, the two groups of listeners had similar psychophysical capacity to discriminate formant frequency changes in non-speech sounds.