Certainly the i in words like bite and fright represents an /aɪ/ diphthong.
Phonemically, I come up with these:
/aɪ/ as in price, my, high, flight, mice/aʊ/ as in mouth, now, trout/eɪ/ as in face, date, day, they, grey, pain, reign/ɔɪ/ as in choice, boy, hoist/oʊ/ as in goat, toe, tow, soul, rope, cold/juː/ as in cute, few, dew, ewe/jə/ as in onion, union, million, scallion, scullion
Most examples are taken from here. What those all actually work out to phonetically varies a great deal across dialects and speakers. For example, many and perhaps even most North American speakers raise the /aɪ/ in tight to [ʌɪ], but not the one in died. You may wish to check out SoundComparisons.COM, where you can both see and hear the phonetic transcriptions for speakers of many, many different dialects, including words like four, hear, eight, cold, cow, fight.
You could also analyse words like way, yay, wow, yow as triphthongs if you really wanted to, although we don’t tend to do so in English. Instead they tend to have an initial /w/ or /j/ followed by a diphthong in normal notation. (In Spanish though they’d be considered triphthongs, as in cambiáis, which has just two syllables, cam- and -biáis.)
Non-rhotic speakers claim to have others, but I have trouble thinking of those as diphthongs myself. I always analyse diphthongs as having a principal vowel to act as the syllabic nucleus and then a glide either before or after it. If the glide comes before the main vowel, as in /jə/, /juː/, it is a rising diphthong, and if the glide comes after the main vowel, as in /aɪ/, /eɪ/, /aʊ/, /oʊ/, /ɔɪ/, it is a falling diphthong. (Some people consider only the falling ones “real” diphthongs. I’m not sure why, since million has only two syllables for me, not three.)
I know of no diphthongs in English that have no glide in them, although whether you write your glides with /j/ and /w/ or as semivowels makes no great difference. This leads to alternate transcriptions, as in /eɪ/ for /ej/, and /aʊ/ for /aw/.
If there is no glide, I don’t count it as a diphthong. That means that I don’t read /ʊə/ as a single syllable. Rather, it has two syllables, as in the programming language named Lua /ˈlʊːə/. I guess I might write that /ˈlʊː.ə/ if I thought people might misunderstand me. And no, it is not homophonic with monosyllabic lure /ˈl(j)ʊːɹ/.
Non-rhotic speakers sometimes analyse words with words with ‹r› in them as diphthongs, where they substitute /ə/ for /ɹ/, but since that’s not a glide, it’s not going to make a new diphthong in my book; it might make a new syllable, though. Even though I say fire /faɪɹ/, I realize that they say /faɪ.ə/. For me that would then rhyme with the disyllabic maya /ˈmɑjɑ/, /ˈmaɪ.ə/, although it becomes challenging to assign the /j/ to one syllable or the other. I don’t see people writing fire /ˈfajəɹ/, but at least then it would seem like two syllables. But you end up reassigning the glide and changing the word from having an /aɪ/ diphthong in the first syllable to having a /jə/ syllable in the second.
For the record, here’s how I see the following r-bearing words:
- bearer
/ˈbe(ɪ)ɹəɹ/
- tourer
/ˈtʰʊɹəɹ/
- nearer
/ˈniːɹəɹ/
- curer
/ˈkʰjʊɹəɹ/
- layer
/ˈleɪ.əɹ/, /ˈle.jəɹ/
- lair
/leɪɹ/
- fiery
/ˈfaɪɹi/ (two syllables), /ˈfa.jəɹi/ (three syllables)
- fairy
/ˈfeɪɹi/
- Faëry
/ˈfe.jəɹi/ (for trisyllabic rhymes in poetry)
- more
/mo(ʊ)ɹ/, /mɔɹ/
- mower
/ˈmoʊ.əɹ/, /ˈmowəɹ/
In that analysis, ‹r› is never part of a diphthong because /ɹ/ is not a glide, and if you write it as a schwa, you’ve likely introduced another second syllable. Non-rhotic AmE speakers (such as those from the South) always sound like they have have more syllables in their words to those of us from the North. The joke is there is no such thing as a one-syllable word in “Suthun”. For example, more is one syllable in the North’s /mo(ʊ)ɹ/, but two in the South’s /ˈmowə/.
Lastly, I realize that you can write ‹-er› as /ɚ/ or /ɹ̩/, as in murder written as either /ˈmərdər/ or /ˈmɝdɚ/. The problem is that we have only two rhotacized IPA symbols, stressed /ɝ/ and unstressed /ɚ/; for anything else that you want rhotacized, you have to use U+02DE MODIFIER LETTER RHOTIC HOOK, which doesn’t look so hot in most fonts, and doesn’t count as a combining character.
Sure, you should practice pronouncing the diphthongs (and trifthongs as well) correctly. Try phonetics practice exercises.
American English Diphthongs by Rachel's English
Listening to your own speech when you repeat after a native speaker record and try to repeat as close to the native speech as possible is very helpful.
Actually, many people who hesitated whether or not they should improve their pronunciation, decided to improve after listening to their own speech recorded.
Just imagine 3 people from different parts of the world speaking and pronouncing the same words each in their own way, and a poor native English speaker trying to make them out.
Everyone should try to bring their English as close to standard as possible, otherwise the internationally used English will be something totally different from native.
Best Answer
No, they do not.
The diphthongs /ɪə, eə, ʊə/ found in Received Pronunciation stem historically from the sequences of /iː/, /eː/ (now /eɪ/), or /uː/ + /r/. In about the 16th century, /iːr/ etc. started to become realized more like [iːər] etc. Later they became more like [ɪər] etc. At this point it would be unreasonable to posit the diphthongs as phonemes because /iː/ etc. were consistently realized as diphthongs before /r/ (so the diphthongs were merely allophones). But then it became fashionable to drop /r/ after vowels in Britain. This gave rise to the diphthongs /ɪə, eə, ʊə/ as distinct phonemes in British English.
General American didn't go through the r-dropping, so even if the diphthongal realizations were retained (which they kind of are—see below), it would be more theoretically sound to analyze the diphthongs as allophones of the long vowels which they originate from. But in GA, /iː, eɪ, uː/ and /ɪ, e, ʊ/ are neutralized before /r/, meaning there are no minimal pairs of /iːr/ etc. and /ɪr/ etc., in that nearer and mirror rhyme and so do Mary and merry (which they do not in RP). This is why some phonemicize near as /niːr/ and others as /nɪr/. (Often the length mark <ː> is omitted and <ɛ> substitutes for <e> in analyses of AmE, but here they are retained for comparison with BrE.)
/niːr/ and /nɪr/ are both defensible, but the latter is more common because key-ring and hearing typically don't rhyme (some pronounce zero, hero, etc. with /iː/, but these are rare exceptions and in free variation with /ɪ/). And although the vowel is short and monophthongal when followed by a vowel, as in caring or nearer, when preceded by a pause or consonant, as in cared or near, the vowel is often diphthongal and resembles the RP counterpart (except followed by /r/). But that doesn't mean they are phonemes in GA, which requires minimal pairs. (Also note marry /ær/ also merges with Marry, merry /er/.)
See Wells's Accents of English (1982), vol. 1, sections 3.2.1 and 3.3.1 for more.
Those who insist on the existence of centering diphthongs as phonemes in AmE do so either because they think that allows for better comparison with RP, because their model accent is different from what linguists have referred to as "General American", "Network English", etc., or because they don't know what they're talking about.