Aspiration of voiceless stops further illustrates the asymmetry of the phonological systems of different languages. Both aspirated and unaspirated voiceless stops occur in English and Thai (the major language spoken in Thailand), but they function differently in the two languages. Aspiration in English is not a phonemic or distinctive feature, because its presence or absence is predictable. In Thai, however, it is not predictable, as the following examples show :
The voiceless unaspirated and the voiceless aspirated stops in Thai are not in complementary distribution. They occur in the same positions in the minimal pairs above; the phones [p, ph, t, th, k, kh] occur. In English they represent the three phonemes /p,t,k/; in Thai they represent the phonemes /p, ph, t, th, k, kh/. Aspiration is a distinctive feature in Thai; it is a non-distinctive or redundant feature in English.
The phonetic facts alone do not reveal what is distinctive or phonemic. The phonetic representation of utterances shows what speakers know about the pronunciation of utterances; the phonemic representation of utterances shows what the speakers know about the abstract underlying phonology. That pot and spot are transcribed with an identical /p/ reveals the fact that English speakers consider the [ ph] in pot, [phɒt], and the [p] in spot, [spɒt], to be phonetic manifestations of the same phoneme /p/.
In learning a language, a child learns which features are distinctive in that language and which are not. One phonetic features may be distinctive for one class of sounds but predictable or non-distinctive for another class of sounds, as, for example, the feature nasality in English. Aspiration in English, on the other hand, is totally predictable and non-distinctive for any class of sounds.
In chapter 6 we mentioned in the discussion of prosodic features that the length of a segment (whether a consonant or vowel is long or short) may be linguistically important.
In some of the world's languages, including many of the dialects of English, you can change the meaning of a word by sustaining the vowel that is, by making it longer. Vowel length is contrastive in Australian English for the three stressed vowels pairs /ɪ/-/i/, /ʌ/-/a/, and /ʊ/-/ɔ/. We could, if we wished, use the symbols /ɪ/ and /ɪ:/, /ʌ/ and /ʌ:/, /ʊ/ and /ʊ:/ to show the contrast more clearly :
For the /ʌ/-/a/ distinction, lengyh appears to be the sole distinguishing factor. The other twp pairs are aided by slight differences in the tongue position.
In addition to those phonemic differences based on length, there are also some differences at the subphonemic or non-phonemic level. All the English vowels occur slightly longer before voiced consonants than before voiceless one, and also at the end of words, as shown in the following examples (where the half-colon [`] marks a slight increase in length ):
Because the vowels with longer duration are predictable, this degree of vowel lengthening is below our level of awareness and is non-phonemic. So, In Australian English, vowel length is an ambivalent feature: it operates at both subphonemic (non-contrastive) and phonemic (contrastive) levels.
In other languages, too, vowel length is non-predictable, and whether a vowel is long or short in duration can distinguish meanings. Vowel length is phonemic in Danish, Finnish, Arabic, and Korean. Consider the following minimal pairs in Korean :
Vowel length is also phonemic in Japanese, as in the following pairs :
When teaching at a university in Japan, one of the authors of this book inadvertently pronounced Ms Tsuji's name as Tsu:ji-san. (The -san is a suffix used to show respect.) The effect of this error quickly taught him to understan the phonemic nature of power length in Japanese.
Consonant length also contrastive in Japanese. A consonant may be lengthened by prolonging the closure: a long t [t:] or [tt] can be produce by holding the tongue against the alveolar ridge twice as long as foe a short t [t]. The following minimal pairs illustrate that length is a phonemic feature for Japanese consonants :
Luganda, an African language, also contrast long and short consonants; /kkula/ means 'treasure' and /kula/ means 'grow up'. (In both these words the first vowel is produced with a high pitch and the second with a low pitch.) The Italian word for 'Grandfather' is nonno /nonno/, cotrasting with the word for 'ninth', which is nono /nono/.
The phonemic contrast between long and short consonants and vowel can be symbolised by the colon, as in /t:/ or /a:/, or by doubling the segment, as it /tt/ or /aa/. Such long segments are sometimes referred to as geminates. Since phonemic symbols are simply cover symbols for a number of distinctive feature values, it does not matter which symbol one uses. This can be shown by specifying the features that distinguish between /nonno/ or /no:o/ and /nono/; the /nn/ or /n:/ is marked as [+ long] and the /n/ as [- long], whichever symbol is used for length.
