What is the difference between /ʌɪ/ and /aɪ/ in English?

Question

Is there any difference between the two diphthongs in English IPA transcriptions?

If I search a word in the Cambridge dictionary, it gives /aɪ/ for both UK English and US English. For example, the word "night" is transcribed as /naɪt/ in Cambridge English dictionary for both UK and US English.

But Lexico (powered by Oxford) gives /nʌɪt/ for "night".

In Cambridge dictionary, I can hear a slight difference between UK and US pronunciation but the IPA symbols are the same.

Dictionary.com also has /aɪ/.

Is there any difference between them? Or can I use /ʌɪ/ and /aɪ/ interchangeably?

Answer 1

The notations /ʌɪ/ and /ɑɪ/ represent a contrastive phonemic difference that some native speakers of English produce and perceive between certain minimal pairs.

For those speakers, the following are minimal pairs differing only in that the first word has the /ʌɪ/ phoneme but the second word has the /ɑɪ/ phoneme:

• writer–rider
• hire–higher
• shire–shyer
• lyre–liar
• bier–buyer
• idle–idol
• ˈhigh school–high ˈschool

Because those are minimal pairs for those speakers, that proves that for them, /ʌɪ/ versus /ɑɪ/ is a phonemic distinction not merely a phonetic one, because changing the sound changes the word in their minds.

This is the phenomenon that has generally come to be known as Canadian raising but it is by no means strictly Canadian. Most native speakers throughout North America make this phonemic distinction, as do some from Northern Ireland.

For such speakers, the raised diphthong /ʌɪ/ occurs in such words as tight, dice, mice, ice, bison, writer, spider, tiger, kind, hire, fire, tire, dire, mire, lyre, bier, sire, shire, choir, pliers, Ireland, inquire, entire, expire, idle, ˈhigh school. However, not all such speakers necessarily have the raised variant in all those terms just listed.

Similarly, for those speakers with this phonemic contrast, the unraised diphthong /ɑɪ/ is (often) found in such words as dyed, dyes, dyer, ire, ion, dine, pine, bind, buys, prize, surmise, rider, scythe, horizon, higher, sigher, shyer, buyer, liar, denier, Oscar Mayer, idol, high ˈschool.

However, if you are referring to allophonic phonetic renditions for the same pair of phonemes, then this requires narrow phonetic transcriptions with complex notation that only specialists are apt to understand.

If so, then the /ʌɪ/ phoneme of ice can variously — depending on the speaker, region, and utterance — be any of [ʌɪ], [ʌ̈ɪ], [äɪ], [ɑ̟i], [äɛ̝̈], [ɐi], [ɐɪ], [ə̠i], [ɛ̈i].

Here are the technical decoded details of what each of those phonetic allophones of the /ʌɪ/ phoneme means:

[ʌɪ]:
 ʌ      open-mid back unrounded vowel           U+028C  LATIN SMALL LETTER TURNED V
 ɪ      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I

[ʌ̈ɪ]:
 ʌ̈      open-mid back unrounded vowel           U+028C  LATIN SMALL LETTER TURNED V
        centralized                             U+0308  COMBINING DIAERESIS
 ɪ      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I

[äɪ]:
 ä      open front unrounded vowel              U+0061  LATIN SMALL LETTER A
        centralized                             U+0308  COMBINING DIAERESIS
 ɪ      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I

[ɑ̟i]:
 ɑ̟      open back unrounded vowel               U+0251  LATIN SMALL LETTER ALPHA
        advanced                                U+031F  COMBINING PLUS SIGN BELOW
 i      close front unrounded vowel             U+0069  LATIN SMALL LETTER I

[äɛ̝̈]:
 ä      open front unrounded vowel              U+0061  LATIN SMALL LETTER A
        centralized                             U+0308  COMBINING DIAERESIS
 ɛ̝̈      open-mid front unrounded vowel          U+025B  LATIN SMALL LETTER OPEN E
        raised                                  U+031D  COMBINING UP TACK BELOW
        centralized                             U+0308  COMBINING DIAERESIS

[ɐi]:
 ɐ      near-open central vowel                 U+0250  LATIN SMALL LETTER TURNED A
 i      close front unrounded vowel             U+0069  LATIN SMALL LETTER I

[ɐɪ]:
 ɐ      near-open central vowel                 U+0250  LATIN SMALL LETTER TURNED A
 ɪ      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I

[ə̠i]:
 ə̠      mid-central vowel                       U+0259  LATIN SMALL LETTER SCHWA
        retracted                               U+0320  COMBINING MINUS SIGN BELOW
 i      close front unrounded vowel             U+0069  LATIN SMALL LETTER I

[ɛ̈i]:
 ɛ̈      open-mid front unrounded vowel          U+025B  LATIN SMALL LETTER OPEN E
        centralized                             U+0308  COMBINING DIAERESIS
 i      close front unrounded vowel             U+0069  LATIN SMALL LETTER I

Compare that set with phonetic realizations of the /ɑɪ/ phoneme of nine, which can be any of [ɑɪ], [ɑˑɪ], [äɪ], [ɑ̈ˑɪ], [ɑ̈ˑɪ̠], [ɑ̟ˑɪ], [äˑɐ], [äˑe̞], [äˑɛ̝̈], [äˑi], [äˑɪ], [ɐˑiˑ], [ɐ̟ˑɪ̠], [ɐˑɪˑ], [ɐi], [ɐiˑ], [ɐɪ], [æˑi], [ɛ̈ˑiˑ], [ɛ̈ĭɪ̠], [ɜ̟ˑiˑ], [ɔ̟ɪ], [ʌ̈ɪ], [ə̟ɪ̝].

Here are the technical decoded details of what each of those phonetic allophones of the /ɑɪ/ phoneme means:

[ɑɪ]:
 ɑ      open back unrounded vowel               U+0251  LATIN SMALL LETTER ALPHA
 ɪ      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I

[ɑˑɪ]:
 ɑˑ     open back unrounded vowel               U+0251  LATIN SMALL LETTER ALPHA
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON
 ɪ      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I

[äɪ]:
 ä      open front unrounded vowel              U+0061  LATIN SMALL LETTER A
        centralized                             U+0308  COMBINING DIAERESIS
 ɪ      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I

[ɑ̈ˑɪ]:
 ɑ̈ˑ     open back unrounded vowel               U+0251  LATIN SMALL LETTER ALPHA
        centralized                             U+0308  COMBINING DIAERESIS
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON
 ɪ      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I

[ɑ̈ˑɪ̠]:
 ɑ̈ˑ     open back unrounded vowel               U+0251  LATIN SMALL LETTER ALPHA
        centralized                             U+0308  COMBINING DIAERESIS
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON
 ɪ̠      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I
        retracted                               U+0320  COMBINING MINUS SIGN BELOW

[ɑ̟ˑɪ]:
 ɑ̟ˑ     open back unrounded vowel               U+0251  LATIN SMALL LETTER ALPHA
        advanced                                U+031F  COMBINING PLUS SIGN BELOW
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON
 ɪ      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I

[äˑɐ]:
 äˑ     open front unrounded vowel              U+0061  LATIN SMALL LETTER A
        centralized                             U+0308  COMBINING DIAERESIS
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON
 ɐ      near-open central vowel                 U+0250  LATIN SMALL LETTER TURNED A

[äˑe̞]:
 äˑ     open front unrounded vowel              U+0061  LATIN SMALL LETTER A
        centralized                             U+0308  COMBINING DIAERESIS
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON
 e̞      close-mid front unrounded vowel         U+0065  LATIN SMALL LETTER E
        lowered                                 U+031E  COMBINING DOWN TACK BELOW

[äˑɛ̝̈]:
 äˑ     open front unrounded vowel              U+0061  LATIN SMALL LETTER A
        centralized                             U+0308  COMBINING DIAERESIS
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON
 ɛ̝̈      open-mid front unrounded vowel          U+025B  LATIN SMALL LETTER OPEN E
        raised                                  U+031D  COMBINING UP TACK BELOW
        centralized                             U+0308  COMBINING DIAERESIS

[äˑi]:
 äˑ     open front unrounded vowel              U+0061  LATIN SMALL LETTER A
        centralized                             U+0308  COMBINING DIAERESIS
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON
 i      close front unrounded vowel             U+0069  LATIN SMALL LETTER I

[äˑɪ]:
 äˑ     open front unrounded vowel              U+0061  LATIN SMALL LETTER A
        centralized                             U+0308  COMBINING DIAERESIS
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON
 ɪ      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I

[ɐˑiˑ]:
 ɐˑ     near-open central vowel                 U+0250  LATIN SMALL LETTER TURNED A
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON
 iˑ     close front unrounded vowel             U+0069  LATIN SMALL LETTER I
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON

[ɐ̟ˑɪ̠]:
 ɐ̟ˑ     near-open central vowel                 U+0250  LATIN SMALL LETTER TURNED A
        advanced                                U+031F  COMBINING PLUS SIGN BELOW
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON
 ɪ̠      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I
        retracted                               U+0320  COMBINING MINUS SIGN BELOW

[ɐˑɪˑ]:
 ɐˑ     near-open central vowel                 U+0250  LATIN SMALL LETTER TURNED A
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON
 ɪˑ     near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON

[ɐi]:
 ɐ      near-open central vowel                 U+0250  LATIN SMALL LETTER TURNED A
 i      close front unrounded vowel             U+0069  LATIN SMALL LETTER I

[ɐiˑ]:
 ɐ      near-open central vowel                 U+0250  LATIN SMALL LETTER TURNED A
 iˑ     close front unrounded vowel             U+0069  LATIN SMALL LETTER I
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON

[ɐɪ]:
 ɐ      near-open central vowel                 U+0250  LATIN SMALL LETTER TURNED A
 ɪ      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I

[æˑi]:
 æˑ     near-open front unrounded vowel         U+00E6  LATIN SMALL LETTER AE
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON
 i      close front unrounded vowel             U+0069  LATIN SMALL LETTER I

[ɛ̈ˑiˑ]:
 ɛ̈ˑ     open-mid front unrounded vowel          U+025B  LATIN SMALL LETTER OPEN E
        centralized                             U+0308  COMBINING DIAERESIS
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON
 iˑ     close front unrounded vowel             U+0069  LATIN SMALL LETTER I
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON

[ɛ̈ĭɪ̠]:
 ɛ̈      open-mid front unrounded vowel          U+025B  LATIN SMALL LETTER OPEN E
        centralized                             U+0308  COMBINING DIAERESIS
 ĭ      close front unrounded vowel             U+0069  LATIN SMALL LETTER I
        extra-short                             U+0306  COMBINING BREVE
 ɪ̠      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I
        retracted                               U+0320  COMBINING MINUS SIGN BELOW

[ɜ̟ˑiˑ]:
 ɜ̟ˑ     open-mid central unrounded vowel        U+025C  LATIN SMALL LETTER REVERSED OPEN E
        advanced                                U+031F  COMBINING PLUS SIGN BELOW
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON
 iˑ     close front unrounded vowel             U+0069  LATIN SMALL LETTER I
        half-long                               U+02D1  MODIFIER LETTER HALF TRIANGULAR COLON

[ɔ̟ɪ]:
 ɔ̟      open-mid back rounded vowel             U+0254  LATIN SMALL LETTER OPEN O
        advanced                                U+031F  COMBINING PLUS SIGN BELOW
 ɪ      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I

[ʌ̈ɪ]:
 ʌ̈      open-mid back unrounded vowel           U+028C  LATIN SMALL LETTER TURNED V
        centralized                             U+0308  COMBINING DIAERESIS
 ɪ      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I

[ə̟ɪ̝]:
 ə̟      mid-central vowel                       U+0259  LATIN SMALL LETTER SCHWA
        advanced                                U+031F  COMBINING PLUS SIGN BELOW
 ɪ̝      near-close near-front unrounded vowel   U+026A  LATIN LETTER SMALL CAPITAL I
        raised                                  U+031D  COMBINING UP TACK BELOW

However, for speakers who have merges in minimal pairs like hire–higher, you should not use different phonemes since those speakers do not make such a distinction.

Dictionaries do not try to represent narrow phonetics. They present broad phonemic transcriptions, virtually always choosing just one of either /ʌɪ/ or /ɑɪ/, and then pretending that everyone says only that version, belying the existence of minimal pairs.

Answer 2

If you click on the U.S. pronunciation in Lexico, it gives /naɪt/ (https://www.lexico.com/en/definition/night).

They represent the same phoneme, and you can pronounce it either way (although it might confuse people if you are not consistent).

The Oxford lexicographers think that [nʌɪt] is becoming the prestigious pronunciation in the U.K., but that the standard pronunciation in the U.S. is still [naɪt]. If you're trying to sound British, you can use the pronunciation [nʌɪt]. If you're trying to speak American English or world English, you should probably use [naɪt]. Much of the rest of the world still uses /naɪt/, although this varies — Australians pronounce it [nɑɪt].

The Cambridge lexicographers haven't bothered changing the pronunciation symbols. There is something to be said for consistency—changing pronunciation symbols confuses people. And even Oxford isn't consistent about changing the symbol when pronunciations change — no dictionaries seem to have changed their IPA symbol for the vowel in nut, even though hardly anybody actually pronounces it [nʌt] anymore.

Many Americans have what is known as "Canadian raising", and use /ʌɪ/ before an unvoiced consonant and /aɪ/ before a voiced consonant, so they would say [nʌɪt] (night) but [raɪd] (ride). Since Americans usually use the same pronunciation for /t/ and /d/ after a stressed syllable and before a vowel, this vowel distinguishes between writer /rʌɪɾər/ and rider /raɪɾər/.

Answer 3

I wouldn’t take tchrist’s answer at face value. As a native speaker of Standard American English (in the Pennsylvania to Colorado belt, so truly the standard) these are at best phonetic differences, certainly not phonemic (plus several of the examples given are clearly triggered by context or simply wrong). Almost none of the examples are truly minimal pairs in my dialect of English, as they assert. Anyway the IPA is for transcribing phonetic rather than phonemic pronunciations so this is ultimately meaningless.