English words. Accordingly, we have learned to ignore it. In Thai, on the other hand, many pairs of words differ only in this respect.
16. Just as English p may be either aspirated or unaspirated, so English b may be voiced or unvoiced. This choice depends less on position in the word than on the identity of the speaker: some people almost always voice b in English, but many others virtually never do. The result, however is the same as for p-ph because the difference between voiced and unvoiced b never carries a difference of meaning in English, we have learned to ignore it.
17. English speakers therefore may have considerable difficulty in hearing the difference between Thai b and p, or between p and ph, or both. Comparable problems exist in dealing with Thai d,t,th; c, ch; k, kh.
18. One logically minor but in practice troublesome fact is that the consonant ŋ which occurs only at the ends of English syllables (e.g. sing) is hard for English speakers to pronounce when it begins a word, as it often does in Thai.
19. 'Though many Thai vowels have similar—sounding counterparts_in English. there are differences in the details of pronunciation.'
If we compare a chart of the simple vowel contrasts of the surface structure of English with a chart of the vowels of Thai, the two charts look virtually identical:
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