2. Method
2.1. Subjects
2.2. Materials
2.2.1. Korean consonants
In Korean, each voiceless stop consonant (p, t or k) can be produced in three ways that differ in laryngeal activity and the timing of laryngeal activity relative to supralaryngeal articulation. The main acoustical correlate of these manners of articulation is VOT and the three types of consonants are named tense, plain and aspirated, in the order of increasing VOTs (see Fig. 2). In Seoul and its surrounding areas, a two-way contrast plain vs. tense is also used to distinguish two /s/ phonemes.
Spectrograms of three syllables differing in the first consonant. From left to ...
Fig. 2.
Spectrograms of three syllables differing in the first consonant. From left to right: tense, plain and aspirared.
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2.2.2. Stimuli
Twenty-four CVCV Korean pseudowords were created with the first syllable always starting with a consonant characteristic of Korean: plain, tense or aspirated [k] or [p] or a plain or tense [s], followed by one of the following vowels: [a], [i] or [u] (each type of consonant co-occurred with each vowel). The second syllable was always [ma]. The pseudowords were recorded by two native speakers of the Seoul dialect of Korean (one woman and one man). The recordings were made in a sound-proof booth, low-pass filtered at 20 kHz and sampled at 16 bits/64 kHz. The pseudowords were excised and saved in different files; their mean duration was 644 ms (SD=78 ms).
We used these 24 pseudowords to create 138 pairs. The first pseudoword was always produced by the male speaker and the second by the female speaker. In 48 pairs, the pseudowords were the same (condition P) and in 48 other pairs, they differed in the first vowel (condition ‘DV’). The remaining pairs involved a difference in the first consonant: 12 pairs included a plain–tense contrast (condition DC1), 12 pairs included a plain–aspirated contrast (DC2), and 12 pairs included a tense–aspirated contrast (DC3); these 36 pairs contrasted the /p/ and /k/ sounds. The last six pairs included a plain–tense contrast with the sound /s/ (condition DS).
Pretesting with four native Korean informants revealed that three pairs of stimuli (one from the DC1 condition and two from the DS condition) were not properly identified as different and were thus excluded from the analyses.