How to pronounce a superscript ə?
This is a very helpful question. Many members here are unsure about what the superscript schwa indicates in dictionaries, and there is a lot of inaccurate information given about it.
The superscript schwa indicates that there are two different pronunciations in common use. One uses a schwa here the other doesn't. So the American version of antonym can be pronounced in the following ways:
- 'æn.tn.ɪm
- 'æn.tə.nɪm
The superscript schwa is not a "small" schwa sound. Neither does it indicate that people disagree about whether there is actually a schwa sound present. It is also not a non-syllabic vowel. As a rule of thumb, whenever we see a syllabic /n, m, l, r/ there will be an alternative pronunciation available with a preceding schwa occurring in the nucleus of the syllable.
Some tips for the production of schwa:
(1) Stand in front of a mirror. Don't close your teeth or open your mouth, just relax your face. Make a sound as if it's coming from your throat or chest (in reality it will be coming from your vocal folds). This should be a schwa sound. In the mirror you should not be able to see your face move at all. If you recorded a video of you practising schwa, but with no sound, we would not know when you were making a sound and when you were silent, because your tongue, jaw and lips - and your face in general - should all be relaxed and not moving at all.
(2) Try to make the sound /b/ as in the word big, but just /b/ on its own. Now try the sound /d/ as in dog and then the sound /g/ as in girl. Do this two or three times. When we say these sounds on their own, we automatically put a little vowel on the end - we have to because they are voiced. If you said the sounds correctly, then you probably said /bə/, /də/ and /gə/. The little vowel that you made by accident after the consonant is a schwa. This is because you were not trying to make any special vowel there.
Schwa only occurs in unstressed syllables. The reason we make schwa like this is because we need to make unstressed syllables shorter than other ones in English. We need the other stressed syllables to be longer and to stand out. The schwa is very quick to make because we do not need to move any of the articulators (the parts of our mouth that we use to make consonants or change the sounds of vowels). If we make a big articulation, a big movement of our mouths, like we do for /æ/ in cat, we need to move our articulators a long way. For /æ/, for example, we have to spread our lips very wide, and drop our jaw very low and move the 'front' (that means the middle) of our tongue so it raises slightly up towards the roof of our mouth. This all takes a lot of time. Because of this, /æ/ is actually quite a long sound, even though it belongs to the so-called 'short vowels'. For a schwa you do not need to move anything! In conclusion then, what you need to do to make a good schwa sound is: nothing!
What it means and what it is are different matters. Making the schwa a superscript here apparently means the sound is non-syllabic. While (except for some diphthongs) you ordinarily have one syllabic sound per syllable, which is the "nucleus" of the syllable, there are some difficult or marginal cases. Syllabic sounds are generally vowels, but liquids like l and r and nasals like n and m can also be syllabic. Syllabic sounds are longer in duration than non-syllabics and acoustically have a "steady state" -- there is a period of time, a few milliseconds, during which the sound doesn't change very much.
Sometimes when a sound that is ordinarily syllabic (a vowel that is) is non-syllabic, that is indicated in a phonetic transcription by making it a superscript. That is perhaps what has been done, here. Schwa is a vowel and is ordinarily syllabic, but in the American pronunciation, the dictionary makers think it is non-syllabic, so they have made it a superscript. Then, comparing the British and American pronunciations given, the British pronunciation has three syllables, "an-to-nym", while the American pronunciation has two syllables, "anton-im". (I am not using phonetic transcriptions here, but rather modified conventional spellings.)
Another possibility here is just some confusion on the part of the dictionary makers. If you click through to this page, http://dictionary.cambridge.org/pronunciation/english/antonym, you'll see another transcription for the American pronunciation that does not have the schwa as a superscript.
As for what the American pronunciation actually is, personally, all I hear in the sound recording is the aspiration after the t, with no vowel sound at all between the t and the n. That is consistent with a syllabification "an-tnym" with just two syllables and the medial vowel lost. Syllable-initial t is aspirated in English, and so aspiration of t would be expected here.
The Cambridge Dictionaries Online has a key where they discuss how they use IPA phonetic symbols. They say:
əl, əm, ən can be pronounced either: əl or ḷ etc.:
Here /ḷ/ stands for a syllabic /l/.
So the IPA stands for two different pronunciations. The t with a vee underneath it is a flapped t. The two pronunciations are:
/ˈæn·təˌnɪm/ or /ˈæn·tṇˌɪm/
where the /t/ is flapped in both pronunciations, and the n with a stroke under it is a syllabic /n/.
The /n/ followed by a flapped /t/ would actually probably be a nasalized flap in real life pronunciations (despite the fact that they're shown as being in different syllables), but Cambridge Dictionaries Online doesn't have a special symbol for that, so they represent it as /nt̬ /.
You really have to ask the editors of the dictionary what they were trying to convey, because choices are inevitably made when applying the IPA. There is even, in fact, a school of thought (that of the Atlas of North American English) that North American English and British English should be transcribed with different systems of vowel notation to account for the fact that North American English does not differentiate vowels in terms of length.