Standard Speech Evaluation Test (Phonemes)

Speech recognition test was assessed using four closed-set identification tasks. The four closed-set identification tasks included English vowel recognition, English consonant recognition, Chinese vowel recognition and Chinese tone recognition.

• English vowel recognition was measured in a 12-alternative identification paradigm. The vowel set included 10 monophthongs and 2 diphthongs, presented in a /h/-vowel-/d/ context. The tokens for vowel recognition test were digitized natural productions from 2 men and 2 women drawn from speech samples collected by Hillenbrand et al. (1995).
• Consonant recognition was measured in a 20-alternative identification paradigm. The consonant set included /b d g p t k m n l r y w f s S v z D tS dZ/, presented in an /a/-consonant-/a/ context. Consonant tokens consisted of digitized natural productions from 2 men and 2 women, for a total of 80 tokens. All consonant tokens were recorded at the House Ear Institute (Shannon et al., 1999).
• Chinese vowel recognition was measured in a 6-alternative identification paradigm. The vowel set included 6 Mandarin Chinese single-vowel syllables (/a/, /o/, /e/, /i/, /u/, /ü/). Chinese vowel tokens consisted of digitized natural productions from 2 men and 2 women, each produced 4 tones for 6 single-vowel syllables., for a total of 96 tokens. All these stimuli were derived from the ‘Chinese Standard Database’ (Wang, 1993).
• Chinese tone recognition was measured in a 4-alternative identification paradigm. All stimuli were same as those in the Chinese vowel recognition test.