Obsolete and nonstandard symbols in the International Phonetic Alphabet
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The International Phonetic Alphabet (IPA) possesses a variety of obsolete and nonstandard symbols. Throughout the history of the IPA, characters representing phonetic values have been modified or completely replaced. An example is ⟨ɷ⟩ for standard [ʊ]. Several symbols indicating secondary articulation have been dropped altogether, with the idea that they should be indicated with diacritics: ʮ for z̩ʷ is one. In addition, the rare voiceless implosive series ƥ ƭ ƭ̢ ƈ ƙ ʠ has been dropped.
Other characters have been added in for specific phonemes which do not possess a specific symbol in the IPA. Those studying modern Chinese phonology have used ⟨ɿ⟩ to represent the sound of -i in Pinyin hanzi which has been variously described as [ɨ], [ɹ̩], [z̩] or [ɯ]. (See the sections Vowels and Syllabic consonants of the article Standard Chinese phonology.)
There are also unsupported symbols from local traditions that find their way into publications that otherwise use the standard IPA. This is especially common with affricates such as ƛ, and many Americanist symbols.
While the IPA does not itself have a set of capital letters (the ones that look like capitals are actually small capitals), many languages have adopted symbols from the IPA as part of their orthographies, and in such cases they have invented capital variants of these. This is especially common in Africa. An example is Kabiyé of northern Togo, which has Ɔ Ɛ Ŋ Ɣ. Other pseudo-IPA capitals supported by Unicode are Ɓ/Ƃ Ƈ Ɗ/Ƌ Ə/Ǝ Ɠ Ħ Ɯ Ɲ Ɵ Ʃ (capital ʃ) Ʈ Ʊ Ʋ Ʒ. (See Case variants of IPA letters.)
Capital letters are also used as cover symbols in phonotactic descriptions: C=Consonant, V=Vowel, N=Nasal, S=Sonorant, etc.
This list does not include commonplace extensions of the IPA, such as doubling a symbol for a greater degree of a feature ([aːː] extra-long [a], [ˈˈa] extra stress, [kʰʰ] strongly aspirated [k], and [a˞˞] extra-rhotic [a][1]), nor superscripting for a lesser degree of a feature ([ᵑɡ] slightly prenasalized [ɡ], [ᵗs] slightly affricated [s], and [ᵊ] epenthetic schwa). The asterisk, as in [k*] for the fortis stop of Korean, is the convention the IPA uses when it has no symbol for a phone or feature.
For symbols and values which were discarded by 1932, see History of the International Phonetic Alphabet.
Symbol or exemplar |
Name | Meaning | Standard IPA equivalent |
Notes |
---|---|---|---|---|
? | question mark | glottal stop | ʔ | typewriter substitution |
7 | digit seven | glottal stop | ʔ | typewriter substitution |
' | apostrophe | glottal stop | ʔ | typewriter substitution |
q | q | glottal stop | ʔ | used in Maltese, Khmer and Malayo–Polynesian languages transcriptions. |
φ | Greek phi | voiceless bilabial fricative | ɸ | a mistake, typewriter substitution or similarity of shape |
ß | sharp s | voiced bilabial fricative | β | a mistake, typewriter substitution or similarity of shape |
∫, ⌠ ⌡ or |
integral symbol | voiceless postalveolar fricative | ʃ | a mistake, typewriter substitution or similarity of shape |
3 | digit three | voiced postalveolar fricative | ʒ | a mistake, typewriter substitution or similarity of shape; often confused with open-mid central unrounded vowel |
đ | d with stroke | voiced dental fricative | ð | a mistake, typewriter substitution or similarity of shape |
þ | thorn | voiceless dental fricative | θ | a mistake |
ƍ | upside-down lowercase delta | labialized voiced alveolar or dental fricative | ðʷ, zʷ, z͎ | intended for the voiced whistled sibilant, ɀ, of Shona and related languages, withdrawn 1976[2] |
σ | lowercase sigma | labialized voiceless alveolar or dental fricative | θʷ, sʷ, s͎ | intended for the voiceless whistled sibilant, ȿ, of Shona and related languages, withdrawn 1976[2] |
ƺ | ezh with tail | labialized voiced postalveolar fricative | ʒᶣ, ʑʷ | intended for w before front vowels in Twi;[2] may also be used for the lightly rounded English /ʒ/, withdrawn 1976. |
ƪ | backwards esh with top loop | labialized voiceless postalveolar fricative | ʃᶣ, ɕʷ | intended for hw before front vowels in Twi;[2] may also be used for the lightly rounded English /ʃ/, withdrawn 1976. |
ƻ | barred digit two | voiced alveolar affricate | d͡z | withdrawn 1976 |
ƾ or ʢ | upside-down voiced epiglottal trill | voiceless alveolar affricate | t͡s | withdrawn 1976 |
ƞ | lowercase eta | moraic nasal | m, n, ŋ, ɴ̩ | Intended for the moraic nasal /N/ of Japanese.[2] Withdrawn 1976 |
◌̡ | palatal hook | palatalization | bʲ cʲ dʲ fʲ ɡ̟ hʲ k̟ lʲ ɬʲ mʲ nʲ ŋ̟ pʲ rʲ ɹʲ ɾʲ sʲ ɕ tʲ vʲ x̟ zʲ ʑ | Typically used in the transcription of Slavic languages such as Russian. Superseded 1989 |
◌̢ | retroflex hook | voiced alveolar or retroflex approximant | ɹ / ɻ | a mistake; an example like /ᶚ/ was actually [ʒ͡ɻ] |
◌̢ | retroflex hook | r-colored vowels | ɜ˞, ə˞ or ɝ, ɚ | Superseded 1989; MODIFIER LETTER RHOTIC HOOK (U+02DE) is now preferred |
unstressed central rhotic vowel | r-colored vowel in American English | ɜ˞, ə˞ or ɝ, ɚ | Proposed in 1934, MODIFIER LETTER RHOTIC HOOK (U+02DE) is now preferred | |
ʃ ʒ t͡ʃ d͡ʒ | alveolo-palatal consonants | ɕ, ʑ, t͡ɕ, and d͡ʑ; respectively | broad transcription; especially Japanologists and Koreanists | |
a | a | any open vowel | Often a substitute for ɑ in printing when the distinction between a and ɑ is not needed. | |
ɑ | lowercase alpha | any open vowel | Often a substitute for ɑ in printing when the distinction between a and ɑ is not needed. | |
a | backwards a | near-open front unrounded vowel | æ | Proposed in 1989, rejected[3] |
c | c | t͡ʃ, t͡ɕ or sometimes t͡s. | broad transcription | |
nv ligature | close front rounded vowel | y | proposed in 1989, rejected[3] | |
ᵿ˞ | barred horseshoe u with hook | back sulcal vowel | proposed in 1989, rejected[3] | |
w with left hook | voiced labial-velar fricative (labialized voiced velar fricative) | ɣʷ | proposed in 1989, rejected[3] | |
letters with left-swinging top hook | dental consonants | d̪ l̪ n̪ r̪ t̪ | proposed in 1989, rejected[3] | |
long-leg g | voiced velar lateral approximant | ʟ | proposed in 1989, rejected[3] | |
ꝣ | hooktop ezh | voiced velar fricative | ɣ | proposed in 1989, rejected[3] |
double-loop g | voiced velar fricative | ɣ | from 1895 to 1900, [q] represented that consonant before 1895, [ǥ] after 1900 | |
double-loop g | voiced velar plosive | ɡ | standard Unicode Basic Latin/ASCII lower-case g (U+0067) may have a double-loop g glyph. the preferred IPA single-loop g (U+0261) is in the IPA Extensions Unicode block. for a time it was proposed that the double-loop g might be used for [ɡ] and the single-loop g for [ᶃ] (ɡ̟),[2] but the distinction never caught on. | |
double-loop g | voiced postalveolar affricate | d͡ʒ | used in Arabic transcriptions | |
single-loop g with stroke | voiced velar fricative | ɣ | replaced double-loop g in 1900, then replaced by gamma [ɣ] around 1928-1930. the character ǥ may not have the single-loop shape in some fonts. | |
j | j | d͡ʒ, d͡ʑ or sometimes d͡z | ||
ɟ | upside-down f | d͡ʒ or d͡ʑ | ||
k̫ ɡ̫ m̫ x̫ p̫ ʒ̫ etc. | subscript w | labialization | kʷ gʷ mʷ xʷ pʷ ʒʷ etc. | mark may appear above letters with descenders like [ɡ] or [ŋ]. removed 1989 |
ʆ | curly-tail esh | voiceless alveolo-palatal fricative | ɕ | variant, also for Russian щ (now ⟨ɕ⟩). removed 1989 |
ʓ | curly-tail ezh | voiced alveolo-palatal fricative | ʑ | variant, removed 1989 |
ȵ, ȡ, ȶ, ȴ | curly-tail n, d, t, l | alveolo-palatal consonants | n̠ʲ, d̠ʲ, t̠ʲ, l̠ʲ or ɲ̟, ɟ˖, c̟, ʎ̟ | used by some Sinologists. |
ř | r with caron | voiced strident apico-alveolar trill | r̝ | Intended for ř in Czech and related languages. ⟨ř⟩ from 1909, replaced by ⟨ɼ⟩ in 1949, Withdrawn 1989 |
ɼ | long-leg r | voiced strident apico-alveolar trill | r̝ | Intended for ř in Czech and related languages. ⟨ř⟩ from 1909, replaced by ⟨ɼ⟩ in 1949, Withdrawn 1989 |
ɼ | long-leg r | syllabic alveolar trill | r̩ | a mistake |
λ ( |
lowercase lambda | voiced palatal lateral approximant | ʎ | a mistake |
λ ( |
lowercase lambda | voiced alveolar lateral affricate | d͡ɮ | used by Americanists |
ƛ | barred lowercase lambda | voiceless alveolar lateral affricate | t͡ɬ | used by Americanists |
ł | lowercase l with stroke | voiceless alveolar lateral fricative | ɬ | used by Americanists, also a typographic substitute |
ł | lowercase l with stroke | velarized voiced alveolar lateral approximant | ɫ | used by Baltic transcriptions |
ᴫ | small-capital Cyrillic el | voiced uvular lateral approximant | ʟ̠ | |
š č ž | s c z with caron | postalveolar consonants | ʃ t͡ʃ ʒ; ʂ ʈ͡ʂ ʐ | used by Americanists, Uralicists, Semiticists, Slavicists |
ǰ, ǧ, ǯ | j, g, ezh with caron | voiced postalveolar affricate | d͡ʒ; ɖ͡ʐ | used by Americanists, Slavicists |
ć ĺ ń ś ź dź | c l n s z dz with acute accent | alveolo-palatals or palatals and postalveolar consonants | t͡ɕ l̠ʲ n̠ʲ ɕ ʑ d͡ʑ; t͡ʃ ʎ ɲ ʃ ʒ d͡ʒ | used by Slavicists |
x, ɣ | x, latin gamma | voiceless and voiced uvular fricative (or voiced uvular approximant) | χ, ʁ or χ, ʁ̞ | broad transcriptions in Hindi, Arabic and Hebrew transcriptions |
ẋ | x with dot | voiceless uvular fricative | χ | used by Americanists |
X | capital x | voiceless uvular fricative | χ | a mistake |
baby gamma | close-mid back unrounded vowel | ɤ | used from 1921 to 1989, replaced by ramshorn to avoid confusion with gamma ; LATIN SMALL LETTER RAMS HORN (U+0264) now represents both glyphs | |
ρ | rho | bilabial trill | ʙ | common before an official letter was adopted |
ɉ | j with stroke | voiced post-palatal approximant | ȷ̈ | |
ᵻ / ᵿ | barred small capital i / upsilon | near-close central unrounded / rounded vowel | ɨ̞ / ʉ̞, ɪ̈ / ʊ̈ | used by the some English phoneticians, including the Oxford English Dictionary |
ʚ | closed epsilon | open-mid front rounded vowel | œ | alternate symbol from 1904-1920s[4] |
ʚ | closed epsilon | open-mid central rounded vowel | ɞ | removed 1996 |
ɩ | small iota | near-close near-front unrounded vowel | ɪ | longstanding alternate symbol until 1989 |
ı | dotless small i | near-close near-front unrounded vowel | ɪ | a mistake or typographic substitute; or used by Americanists. |
ȸ ȹ | lowercase db and qp ligatures or lowercase footless phi and headless phi | voiced and voiceless labiodential plosives | b̪ p̪ | Used by Africanists. |
0, ∅ or Ø | digit zero, slashed digit zero or uppercase slashed o | null initial | usually used in phonology to mean a spelling with no sound value. however, in Chinese and some Korean linguistics, some scholars use it for a weak glottal stop; the sound value of the first consonant of syllables started by a vowel. | |
ƥ ƭ 𝼉 ƈ ƙ ʠ | hooktop p, t, ʈ, c, k, q | voiceless implosives | ɓ̥ ɗ̥ ᶑ̥ ʄ̊ ɠ̊ ʛ̊ or pʼ↓ tʼ↓ ʈʼ↓ cʼ↓ kʼ↓ qʼ↓ | brief additions to the IPA; removed 1993 |
ʇ | upside-down t | dental click | ǀ | removed 1989; see click letters |
ʗ | stretched (or descended) c | alveolar click | ǃ | removed 1989; see click letters |
ʖ | upside-down pharyngeal fricative | alveolar lateral click | ǁ | removed 1989; see click letters |
ʞ | upside-down k | originally a palatal click, reinterpreted as a velar click | velar articulation was judged impossible.[5] later reanalyzed and found paralinguistically. For several years used for a voiceless velodorsal stop in the extIPA.[6] | |
𝼋 (⨎) | esh with two bars | fricated palatal click | ǂǂ or ǃ͡s | uncommon letter in Ekoka !Kung transcription |
⦀ | triple vertical bar | retroflex lateral click | ǁ˞ | |
ȣ | ou | close-mid back unrounded vowel or voiced velar fricative | ɤ or ɣ | a common mistake |
r | r | alveolar trill | any rhotic sound (including r-colored vowels) | broad transcription |
ʀ or R | small capital or uppercase r | long vowel or prolonged moraic N | ː | used by Japanologists. This symbol represents phonemic long vowel (such as /aʀ/) or /aR/) or rarely prolonged moraic N (hatsuon). |
ᴙ | reversed small capital r | voiced epiglottal trill[citation needed] | ʀ̠ or ʢ | rare |
ɿ | long i with left hook | syllabic denti-alveolar approximant | ɹ̩,[7] ɹ̩, z̩, ◌͡ɯ[8] | used by Sinologists, and by Japanologists specifically for the Miyako language |
ʅ | viby i | syllabic retroflex approximant | ɹ̩,[7] ɻ̩, ʐ̩, ◌͡ɨ | used by Sinologists. See Chinese vowels |
ʮ | long y with left hook | labialized syllabic denti-alveolar approximant | ɹ̩ʷ, z̩ʷ, ◌͡u | used by Sinologists |
ʯ | viby ü or viby y | labialized syllabic retroflex approximant | ɻ̩ʷ, ʐ̩ʷ, ◌͡ʉ | used by Sinologists |
ᴀ | small capital a | open central unrounded vowel | ä, a̠, ɑ̈, ɑ̟, ɐ̞ | used by Sinologists |
Ɐ | small capital turned a | close-mid back unrounded vowel | ɤ | withdrawn in 1928. |
ꬰ | barred alpha | open central unrounded vowel | ä, a̠, ɑ̈, ɑ̟, ɐ̞ | used by Teuthonista |
ᴇ | small capital e | mid front unrounded vowel | e̞, ɛ̝ | Bloch & Trager (1942). Used by Sinologists and some Koreanists |
ꬳ | barred e | close-mid central unrounded vowel | ɘ | used by Teuthonista |
ⱻ | small capital turned e | mid back unrounded vowel | ɤ̞, ʌ̝ | used by some Koreanists who study Gyeongsang dialect, where there is no phonemic differentiation between /ʌ/ (RR eo; Hangul ㅓ) and /ɯ/ (RR eu; Hangul ㅡ).[citation needed] |
ɷ | closed omega | near-close near-back rounded vowel | ʊ | longstanding alternate symbol until 1989 |
ω | lowercase omega | near-close near-back unrounded vowel | ʊ̜ or ɯ̽ | made from obsolete ɷ symbol. |
ω | lowercase omega | near-open back rounded vowel | ɔ̞ or ɒ̝ | used by Sinologists ; also Bloch & Trager (1942). |
ꭥ | small capital omega | mid back rounded vowel | o̞, ɔ̝ | Used by Sinologists and some Koreanists ; also Bloch & Trager (1942). |
ꝋ | barred o | close-mid central rounded vowel | ɵ | used by Teuthonista |
ᴜ | small capital u | near-close near-back rounded vowel | ʊ, ʊ̹ | Americanist notation |
B G Ɠ H I L N Œ R Y | uppercase letters | small сарs | ʙ ɢ ʛ ʜ ɪ ʟ ɴ ɶ ʀ ʏ | often mistaken by typing, uppercase alternatives to symbols shaped like small capitals |
ꞯ | small capital q | pharyngeal stop | ʡ | proposed for the pharyngeal stop of Formosan languages, ExtIPA for same purpose. |
ꞯ | small capital q | sokuon | used by Japanologists. | |
Q | capital Q | used by Japanologists. | ||
l | l | all coronal liquid consonants. | broad transcription, mainly Koreanologists. | |
ꞎ 𝼆 𝼄 | belted letters | voiceless lateral fricatives (retroflex, palatal, velar, and alveolar) | ɭ̥˔ ʎ̥˔ ʟ̥˔ | now in the extIPA[6] |
ʎ | upside-down y | alveolo-palatal lateral approximant | [ʎ̟] or [l̠ʲ] | broad transcription, mainly Koreanologists and Sinologists |
ɲ | n with left hook | alveolo-palatal nasal | [ɲ̟] or [n̠ʲ] | broad transcription, mainly Koreanologists, Sinologists, and Japanologists |
ⱳ | w with hook | bilabial flap | ⱱ̟ | |
𝼈 | turned r with long leg and retroflex hook | retroflex lateral flap | ɭ̆ | |
ɏ | barred y | close central compressed vowel | ÿ | |
barred small capital y | near-close central compressed vowel | ʏ̈ | ||
ұ | barred straight y (Cyrillic straight u) | near-close near-back unrounded vowel | [ʊ̜] or [ɯ̽] | used in Mande studies[9] |
◌̣ | underdot | retroflex or r-colored vowels | ɑ˞ o˞ etc. | |
k', t', etc. | apostrophe | no audible release | k̚, t̚, etc. | removed |
k', t', etc. | apostrophe | palatalization | k̟, tʲ, etc. | common in X-SAMPA |
K T etc. | uppercase letters (not small capitals) | fortis | k͈ t͈, etc. | used by some Koreanologists |
ɔ̩ | vowel with tilted line below | lower-pitched rising / falling tone contour | for languages that distinguish multiple rising or falling tones | |
kʻ tʻ | reversed comma above | weak (sometimes normal) aspiration | k t (sometimes kʰ tʰ) | First symbol may be left single quotation mark (U+2018) or modifier letter apostrophe (U+02BC); second symbol may be single high-reversed-9 quotation mark (U+201B) or modifier letter reversed comma (U+02BD) |
ʦ ʣ ʧ ʤ ꭧ ꭦ ʨ ʥ | ligatures | affricates | t͡s d͡z t͡ʃ d͡ʒ ʈ͡ʂ ɖ͡ʐ t͡ɕ d͡ʑ | formerly acceptable variants[10] |
p′ s′ t′ etc. | prime | palatalization | pʲ sʲ tʲ etc. | traditional Irish phonology transcription |
pʼ sʼ tʼ etc. | combining apostrophe | palatalization | pʲ sʲ tʲ etc. | traditional Russian phonology transcription |
* | asterisk | syntactic gemination | (none) | used in some Italian dictionaries |
˹ | open corner | release/burst | (none) | IPA number 490 |
d d͡ɮ d͡z l ɫ ɬ ɮ n r ɹ ɾ s t t͡ɬ s z | without diacritics | dental consonants | d̪ d̪͡ɮ̪ d̪͡z̪ l̪ ɫ̪ ɬ̪ ɮ̪ n̪ r̪ ð̞ ɾ̪ s̪ t̪ t̪͡ɬ̪ t̪͡s̪ z̪ | broad transcriptions; in some English dialects, /ð̞/ often described as ⟨ɹ̪⟩ for /r⁓ɹ/ |
β ð ʝ ɣ ʁ ʕ or e ø ɘ ɵ ɤ o | without diacritics | approximant consonants or mid vowels | β̞ ð̞ j ɰ ʁ̞ ʕ̞ or e̞ ø̞ ə ɵ̞ ɤ̞ o̞ | broad transcriptions; in Spanish, /j/ and /ɰ/ often described as ⟨ʝ̞⟩ and ⟨ɣ̞⟩ |
ɛ œ ɜ ɞ ʌ ɔ | without diacritics | mid vowels | e̞ ø̞ ə ɵ̞ ɤ̞ o̞ | broad transcriptions; for example in some languages, /e̞/ and /o̞/ maybe described as ⟨ɛ̝⟩ and ⟨ɔ̝⟩, also /ə/ maybe described as ⟨ɘ̞⟩ or ⟨ɜ̝⟩ |
ɪ ʊ a ɒ | without diacritics | central vowels | ɪ̈ ʊ̈ ä ɒ̈ | broad transcriptions; in some English dialects, /ä/ often described as ⟨ɑ̈⟩ in English for /ɑ/ |
c or ȼ | c or stroked c | voiceless alveolar affricate | t͡s | Americanist notation |
ʒ | ezh | voiced alveolar affricate | d͡z | Americanist notation |
y | y | voiced palatal approximant | j | Americanist notation |
ä | a with diaeresis | open front unrounded vowel or near-open front unrounded vowel | a or æ | Uralicist notation |
ö | o with diaeresis | mid front rounded vowel | ø̞ | Americanist and Uralicist notation |
ü | u with diaeresis | close front rounded vowel | y | Americanist and Uralicist notation |
k’ t’ etc. | right single quotation mark | Korean fortis | k͈ t͈ etc. | used by some Koreanists for fortis sounds; equivalent to ⟨k*⟩, etc. above. |
◌⸋ | box | unreleased | ◌̚ | used where IPA ◌̚ would get confused with the corners used to indicate change of pitch in the Japanese pitch accent system |
◌ʱ | breathy/ voiced aspiration | ◌̤ | ||
◌ˀ | creaky voice/ glottalization | ◌̰ | ||
◌̴ | velarization | ◌ˠ | ||
ˉ◌, ˗◌, ˍ◌ | high, mid and low-level tone or intonation | removed | ||
˭◌, ₌◌ | extra-high and extra-low level tone or intonation | removed | ||
ˋ◌, ˴◌, ˎ◌ | falling or high falling, mid falling and low-falling tone or intonation | removed | ||
ˊ◌, [NA], ˏ◌ | (high) rising and low rising tone or intonation | removed | ||
ˇ◌, ˬ◌ | (high) dipping and low dipping (falling-rising) tone or intonation | removed | ||
ˆ◌, ꞈ◌ | peaking (rising-falling) tone or intonation | removed | ||
˜◌, ̰◌ | "wavy" tone or intonation | removed | ||
˙◌, ·◌, .◌ | atonic syllable with high, mid, and low pitch; respectively | removed | ||
◌́, ◌̂, ◌̀, ◌̆ | Acute accent, circumflex, grave accent, breve | stress symbols:
primary stress, weakened primary stress, secondary stress, and no stress; respectively |
ˈˈ◌, ˈ◌, ˌ◌, ◌ | some English phoneticians and phonologists use acute and grave accents as primary and secondary stress symbols. Some linguists[11] use the circumflex as weakened primary stress in compound words and the breve as no stress. these symbols are also written on the English spellings not just other IPA symbols. |
◌̩, ◌̍ | Vertical line below or above | moraic | used by Japanologists. In the standard IPA, these symbols represents syllabic sounds, but Japanologists use them for phonetic variants (except for nasal vowels) of the moraic N ([n̩, ɴ̩, ŋ̍ (or ŋ̩), m̩]). | |
◌̄, ◌́, ◌̌, ◌̀ | Macron, acute accent, caron, grave accent | Chinese tones | ◌́, ◌̌, ◌̀, ◌̂ or similar, depending on dialect and analysis, or Chao tone letters | used by Sinologists with the values the symbols have in Hanyu Pinyin. the standard IPA values of these diacritics are: mid, high, rising, and low tone. |
See also
[edit]Footnotes or references
[edit]- ^ Ladefoged, Peter; Maddieson, Ian (1996). Sounds of the World's Languages. Oxford: Blackwell. pp. 313–314.
- ^ a b c d e f 1949 Principles of the IPA
- ^ a b c d e f g Henton, C. G. (1988). 5. Individual symbols and diacritics. Journal of the International Phonetic Association, 18(02), 85. doi:10.1017/s0025100300003686
- ^ 1912 Principles of the IPA
- ^ An impossible sound
- ^ a b "extIPA Symbols for Disordered Speech (Revised to 2015)" (PDF). Retrieved 15 February 2018.
- ^ a b Lee-Kim, Sang-Im (December 2014). "Revisiting Mandarin 'apical vowels': An articulatory and acoustic study". Journal of the International Phonetic Association. 44 (3): 261–282. doi:10.1017/S0025100314000267. S2CID 16432272.
- ^ Lee, Wai-Sum; Zee, Eric (June 2003). "Standard Chinese (Beijing)". Journal of the International Phonetic Association. 33 (1): 109–112. doi:10.1017/S0025100303001208.
- ^ Roberts, David; Boyd, Ginger; Merz, Johannes; Vydrin, Valentin (2020). "Quantifying written ambiguities in tone languages: A comparative study of Elip, Mbelime, and Eastern Dan". Language Documentation & Conservation. 14: 108–138. hdl:10125/24915.
- ^ Pullum, Geoffrey K.; William A. Ladusaw (1996). Phonetic Symbol Guide (2nd ed.). University of Chicago Press. p. 180. ISBN 0-226-68535-7.
- ^ Trager, George L., and Henry Lee Smith Jr. 1951. An Outline of English Structure. Studies in Linguistics: Occasional Papers 3. Norman, Okla.: Battenburg Press.