Extensions to the International Phonetic Alphabet

For the Unicode block, see IPA Extensions. For other extensions to the IPA, see Voice Quality Symbols and Sinological extensions to the IPA.

The Extensions to the International Phonetic Alphabet for Disordered Speech, commonly abbreviated extIPA /ɛkˈstaɪpə/,^[1] are a set of letters and diacritics devised by the International Clinical Phonetics and Linguistics Association to augment the International Phonetic Alphabet for the phonetic transcription of disordered speech. Some of the symbols are used for transcribing features of normal speech in IPA transcription, and are accepted as such by the International Phonetic Association.^[a]

Extended IPA Chart for Disordered Speech, as of 2015

Many sounds found only in disordered speech are indicated with diacritics, though an increasing number of dedicated letters are used as well. Special letters are included to transcribe the speech of people with lisps and cleft palates. The extIPA repeats several standard-IPA diacritics that are unfamiliar to most people but transcribe features that are common in disordered speech. These include preaspiration ⟨ʰ◌⟩, linguolabial ⟨◌̼⟩, laminal fricatives [s̻, z̻], and ⟨*⟩ for a sound (segment or feature) with no available symbol (letter or diacritic). The novel transcription ⟨ɹ̈⟩ is used for an English molar-r, as opposed to ⟨ɹ̺⟩ for an apical r; these articulations are indistinguishable in sound and so are rarely identified in non-disordered speech.

Sounds restricted to disordered speech include velopharyngeals, nasal fricatives (a.k.a. nareal fricatives) and some of the percussive consonants. Sounds sometimes found in the world's languages that do not have symbols in the basic IPA include denasals, the sublaminal percussive, palatal and velar lateral fricatives, and fricatives that are simultaneously lateral and sibilant.

ExtIPA was revised and expanded in 2015; the new symbols were added to Unicode in 2021.^[2]

Letters

The non-IPA letters found in the extIPA are listed in the following table. VoQS letters may also be used, as in ⟨ↀ͡r̪͆⟩ for a buccal interdental trill (a raspberry), as VoQS started off as a subset of extIPA.^[3]

Several letters and superscript forms were added to Unicode 14 and 15. They are included in the free Gentium Plus and Andika fonts.

Category	Letter	Superscript and example		Unicode	Description
Lateral	ʪ	𐞙	[t𐞙]	U+02AA, U+10799	Voiceless grooved lateral alveolar fricative, [ɬ͡s] (a laterally lisped /s/, with simultaneous airflow through the sibilant groove in the tongue and across the side of the tongue), intended for a lateral lisp
	ʫ	𐞚	[d𐞚]	U+02AB, U+1079A	Voiced grooved lateral alveolar fricative, [ɮ͡z] (a laterally lisped /z/)
	ꞎ	𐞝	[ʈ𐞝]	U+A78E, U+1079D	Voiceless retroflex lateral fricative, implicit in standard IPA.
	𝼅	𐞟	[ɖ𐞟]	U+1DF05, U+1079F	Voiced retroflex lateral fricative, implicit in standard IPA.
	𝼆	𐞡	[c𐞡]	U+1DF06, U+107A1	Voiceless palatal lateral fricative. The voiced fricative may be ⟨𝼆̬⟩ or, in standard IPA, ⟨ʎ̝⟩.
	𝼄	𐞜	[k𐞜]	U+1DF04, U+1079C	Voiceless velar lateral fricative. The voiced fricative may be ⟨𝼄̬⟩ or, in standard IPA, ⟨ʟ̝⟩.
Velo­pharyngeal	ʩ	𐞐	[s𐞐]	U+02A9, U+10790	Voiceless velopharyngeal fricative (often occurs with a cleft palate). The voiced fricative is ⟨ʩ̬⟩.
	𝼀	𐞐𐞪	[s𐞐𐞪]	U+1DF00, (U+10790+107AA)	Voiceless velopharyngeal trill or 'snort'. (Velopharyngeal fricative accompanied by uvular trill. [𝼀] may be equivalent to [ʩ𐞪].)
Velo­dorsal	𝼃	–		U+1DF03	Voiceless velodorsal plosive. (The old IPA letter for a velar click, ⟨ʞ⟩, was provided for a voiceless velodorsal plosive from 2008 to 2015.)
	𝼁	–		U+1DF01	Voiced velodorsal plosive
	𝼇	–		U+1DF07	Velodorsal nasal
Pharyn­geal	ꞯ	–		U+A7AF	Voiceless upper-pharyngeal plosive [q˗] or [ʡ̟]
	𝼂	–		U+1DF02	Voiced upper-pharyngeal plosive [ɢ̠] or [ʡ̟̬]
Percussive	ʬ	–		U+02AC	Bilabial percussive (for lips smacking together; cf. non-percussive [ʬ↓] for lips smacking apart)
	ʭ	–		U+02AD	Bidental percussive (gnashing teeth)
	¡	ꜞ	[ǃꜞ], [ǂꜞ]	U+00A1, U+A71E	Sublaminal lower-alveolar percussive (tongue slap). Used with letters for alveolar and palatal clicks to indicate clicks with percussive release, or "clucks", [ǃ¡] and [ǂ¡].

Diacritics

The extIPA has widened the use of some of the regular IPA symbols, such as [ʰp] for pre-aspiration and [tʶ] for uvularization, and has added some new ones. Some of these extIPA diacritics are occasionally used for non-disordered speech, for example for the unusual airstream mechanisms of Damin.

One modification of regular IPA is the use of parentheses around the phonation diacritics to indicate partial phonation; a single parenthesis at the left or right of the voicing indicates that it is partially phonated at the beginning or end of the segment. These conventions may be convenient for representing various voice onset times. Phonation diacritics may also be prefixed or suffixed to represent relative timing beyond the segment (pre- and post-voicing etc.). The following are examples; in principle, any IPA or extIPA diacritic may be parenthesized or displaced in this manner.^[3]

Partial phonation (examples)
s̬᪽	partial/central voicing of [s]	z̥᪽ ʒ̊᪻	partial/central devoicing of [z], [ʒ]	subscript: U+1ABD; superscript: 1ABB
s̬᫃	initial voicing	z̥᫃	initial devoicing	subscript: U+1AC3; superscript: 1AC1
s̬᫄	final voicing	z̥᫄	final devoicing	subscript: U+1AC4; superscript: 1AC2
z̤᪽	partial murmuring of [z]	n͊᪻	partially denasalized [n]
Displaced timing (examples)
ˬz	pre-voiced [z]	zˬ	post-voiced [z]	U+02EC
a˷	[a] with a creaky offglide	p˳	[p] with extended voicelessness	U+02F7 (˷), U+02F3 (˳)

The transcriptions for partial voicing and devoicing may be used in either the sense of degrees of voicing or in the sense that the voicing is discontinuous. For the former, both parentheses indicate the sound is mildly (partially) voiced throughout, and single parentheses mean a partial degree of voicing at the beginning or end of the sound. For the latter, both parentheses mean the sound is (de)voiced in the middle, while the single parentheses mean complete (de)voicing at the beginning or end of the sound. The implication is that such voicing or devoicing is atypical of the language being spoken. For example, ⟨z̥⟩ would be used for the usual devoicing or partial devoicing of the language, while ⟨z̥᪽⟩ would indicate that the transcriber found the devoicing to be atypical, as in pathological speech. Similarly, ⟨z̥᫃⟩ would indicate atypical devoicing at the beginning of the segment.^[4]

Altering the position of a diacritic relative to the letter indicates that the phonation begins before the consonant or vowel does or continues beyond it. The voiceless ring and other phonation diacritics can be used in the same way if needed. For example, ⟨p˳a⟩ indicates that voicelessness continues past the [p], more or less equivalent to ⟨pʰa⟩.

Other extIPA diacritics are:^[3]

Airstream mechanism
ɬ↓, ə↓	U+2193	(after a letter) Ingressive airstream	ʘ↑	U+2191	(after a letter) Egressive airstream[b]
↓		(in isolation) inhalation[4]	↑		(in isolation) exhalation[4]
Phonation
p˭	U+02ED[c]	Unaspirated	ʰp	U+02B0	Pre-aspiration
Nasalization
n͋[d]	U+034B	(on a nasal letter) Nareal fricative	s͌ or s𐞐	U+034C[e] or U+10790	Velopharyngeal friction (especially noisy nasal airstream caused by turbulent airflow through the velopharyngeal port)
v͋		(on an oral letter) nasal fricative escape (audible turbulent airflow through the nostrils, as with a nasal lisp)	m͊	U+034A	Denasal (as with a headcold; complements the nasal diacritic)
Articulatory strength
f͈, h͈	U+0348	Strong articulation (not necessarily fortis); ⟨h͈⟩ may be used for a true glottal fricative	v͉	U+0349	Weak articulation (not necessarily lenis)
Articulation
v͆	U+0346	(on a labial letter) Dentolabial	n̪͆	U+0346  +032A	(on a coronal letter) interdental
t͆		(on a coronal letter) class-3 occlusion (tongue protrudes past upper teeth, as with a severe underbite)	h̪͆		(on a glottal letter) bidental
s͇	U+0347[f]	(on a coronal letter) Alveolar[g]	s͍	U+034D	Labial spreading
f͇		(on a labial letter) labioalveolar (class-2 occlusion, as with a severe overbite)	o͍		(complements the diacritics for rounding – see rounded vowel)[h]
s͎	U+034E	Whistled	s̻ z̻	U+033B	laminal fricatives (including lowered tongue tip)[i]
ɹ̈, ɹ̺	(as IPA)	bunched-r (molar-r), and apical-r, respectively	s͕, s͔	U+0355, U+0354	Offset to the left and right, respectively[j]
Timing
s͢θ  x͢ɕ	U+0362	Slurred/sliding articulation (a consonantal diphthong, moving from one articulation to another within the time of a single segment)	p\p\p	U+005C	Stutter (reiterated articulation)[k]

Diacritics may be placed within parentheses as the voicing diacritics are above. For example, ⟨m͊᪻⟩ indicates a partially denasalized [m].

The arrow for sliding articulation was first used for [wɑət̪s̪͢θ] for 'watch' and [z̪͢ðɪpʊə] for 'zipper'. It is most commonly observed in quick changes from the blade to the tip of the tongue (laminal to apical) in plosives and fricatives, such as [t̪͢t] and [t͢θ], or vice versa, but is not limited to that; the consonants may also be labial or dorsal, e.g. [ɸ͢f] and [k͢q].^[7]

The slit-grooved distinction of the channel shape of front fricatives may be handled with these diacritics, with for example ⟨s̪ z̪⟩ for grooved (sibilant) dental fricatives, and ⟨θ͇ ð͇⟩ for ungrooved (non-sibilant) aveolar fricatives. This is a common topic in speech pathology, though ⟨s̪ z̪⟩ occur in non-pathological speech in some languages.^[7]

Any IPA letter may be used in superscript form as a diacritic, to indicate the onset, release or 'flavor' of another letter. In extIPA, this is provided specifically for the fricative release of a plosive. For example, ⟨k𐞜⟩ is [k] with a lateral-fricative release (similar to the velar lateral affricate [k͜𝼄], but with less frication); ⟨d𐞚⟩ is [d] with lateral-plus-central release. Combining diacritics can be added to superscript diacritics, such as ⟨tʰ̪͆⟩ for [t] with bidental aspiration.

The VoQS (voice-quality symbols) take IPA and extIPA diacritics, as well as several additional diacritics that are potentially available for extIPA transcription. The subscript dot for 'whisper' is sometimes found in IPA transcription,^[8] though in IPA the diacritic has also been used for apical-retroflex articulation.

Prosodic notation and indeterminate sounds

The Extended IPA has adopted bracket notation from conventions transcribing discourse. Parentheses are used to indicate mouthing (silent articulation), as in the common silent sign to hush (ʃːː). Parentheses are also used to indicate silent pauses, for example (...); the length of the pause may be indicated, as in (2.3 sec). A very short (.) may be used to indicate an absence of co-articulation between adjacent segments, for instance [t(.)weɫv̥] rather than [tʷw̥eɫv̥].^[9]

Double parentheses indicate that transcription is uncertain because of extraneous noise or speech, as when one person talks over another. As much detail as possible may be included, as in ⸨2 syll.⸩ or ⸨2σ⸩ for two obscured syllables.^[10] This is also IPA usage.^[11] Sometimes the obscuring noise will be indicated instead, as in ⸨cough⸩ or ⸨knock⸩, as in the illustrative transcription below; this notation may be used for extraneous noise that does not obscure speech, but which the transcriber nonetheless wishes to notate (e.g. because someone says 'excuse me' after coughing, or verbally responds to the knock on the door, and the noise is thus required to understand the speech).

In the extIPA, indistinguishable/unidentifiable sounds are circled rather than placed in single parentheses as in IPA.^[l] An empty circle, ◯, is used for an indeterminate segment, ◯ σ  an indeterminate syllable, Ⓒ a segment identifiable only as a consonant, etc. Full capital letters, such as C in Ⓒ, are used as wild-cards for certain categories of sounds, and may combine with IPA and extIPA diacritics. For example, ◯ P̥   indicates an undetermined or indeterminate voiceless plosive. Regular IPA and extIPA letters may also be circled to indicate that their identification is uncertain. For example, ⓚ indicates that the segment is judged to probably be [k]. This is effectively a copy-edit mark, and may be elongated into an oval for longer strings of symbols. This was illustrated in the 1997 edition of the chart, where the circle was typeset as ( ̲̅) and longer strings as e.g. (a̲̅a̲̅a̲̅). There is no way to typeset this in Unicode that does not require spurious characters between the letters (as here), but it may be graphically approximated with an unused set of brackets, such as ⦇aaa⦈.

Curly brackets with Italian musical terms are used for phonation and prosodic notation, such as [{_falsetto ˈhɛlp _falsetto}] and terms for the tempo and dynamics of connected speech. These are subscripted within a {curly brace} notation to indicate that they are comments on the intervening text. The VoQS conventions use similar notation for voice quality. These may be combined, for example with VoQS ⟨F⟩ for 'falsetto':

{_allegro I {F {_𝆏 didn't _𝆏} know that F} _allegro}

or

[{_allegro ə {F {_𝆏 dɪn _𝆏} nəʊ ðæʔ F} _allegro}]^[9]

Silence
(  )	Silent articulation: (ʃːː) a silent shhh!
(.)	Short pause	(..)	Medium pause	(...)	Long pause	(1.2)	1.2-second pause
Prosody
𝆑	Loud speech ('forte')	[{𝆑 ˈlaʊd 𝆑}]		𝆑𝆑	Louder speech ('fortissimo')	[{𝆑𝆑 ˈlaʊdɚ 𝆑𝆑}]
𝆏	Quiet speech ('piano')	[{𝆏 ˈkwaɪət 𝆏}]		𝆏𝆏	Quieter speech ('pianissimo')	[{𝆏𝆏 ˈkwaɪətɚ 𝆏𝆏}]
allegro	Fast speech	[{allegro ˈfæst allegro}]		lento	Slow speech	[{lento ˈsloʊ lento}]
crescendo, rallentando, and other musical terms may also be used.
Extraneous noise; speech obscured by extraneous noise
⸨  ⸩	⸨2σ⸩ two syllables obscured; ⸨cough⸩ a cough
Unidentified and partially identified sounds in recordings
◯	segment	Ⓒ	consonant	Ⓕ	fricative	Ⓖ	glide/approximant
Ⓚ[m]	click	Ⓛ	liquid (or lateral)	Ⓝ	nasal	Ⓟ	plosive
Ⓡ	rhotic (or resonant)	Ⓢ	sibilant	Ⓣ	tone/accent/stress	Ⓥ	vowel

Chart

Three rows appear in the extIPA chart that do not occur in the IPA chart: "fricative lateral + median" (simultaneous grooved and lateral frication), "fricative nasal" (a.k.a. nareal fricative) and "percussive". A denasal row is added here. Several new columns appear as well, though the linguolabial column is the result of a standard-IPA diacritic. Dorso-velar and velo-dorsal are combined here, as are upper and lower alveolar.

Consonants not appearing on the standard IPA chart

	bi- labial	labio- dental	labio- alveolar	dento- labial	bi- dental	linguo- labial	inter- dental	alveolar (lower alveolar)	retro- flex	pala- tal	velar (velo- dorsal)	velo- phary- ngeal	upper phary- ngeal
Plosive		p̪ b̪	p͇ b͇	p͆ b͆		t̼ d̼	t̪͆ d̪͆				(𝼃 𝼁)		ꞯ 𝼂
Denasal	m͊							n͊	ɳ͊	ɲ͊	ŋ͊
Nasal			m͇	m͆		n̼	n̪͆				(𝼇)
Fricative nasal	m̥͋ m͋							n̥͋ n͋	ɳ̥͋ ɳ͋	ɲ̥͋ ɲ͋	ŋ̥͋ ŋ͋
Trill						r̼	r̪͆					𝼀 (ʩ𐞪)
Median fricative			f͇ v͇	f͆ v͆	h̪͆ ɦ̪͆	θ̼ ð̼	θ̪͆ ð̪͆	θ͇ ð͇				ʩ ʩ̬
Lateral fricative[n]						ɬ̼ ɮ̼	ɬ̪͆ ɮ̪͆		ꞎ 𝼅	𝼆 𝼆̬	𝼄 𝼄̬
Mediolateral fricative								ʪ ʫ
Lateral approximant						l̼	l̪͆
Percussive	ʬ				ʭ			(¡)

Superscript variants

Further information: Superscript IPA letters

The customary use of superscript IPA letters is formalized in the extIPA, specifically for fricative releases of plosives, as can be seen in the lower-left of the full chart.

Speech pathologists also often use superscripting to indicate that a target sound has not been reached – for example, [ˈtʃɪᵏən] for an instance of the word 'chicken' where the /k/ is incompletely articulated. However, due to the ambiguous meaning of superscripting in the IPA, this is not a convention supported by the ICPLA. An unambiguous transcription would mark the consonant more specifically as weakened ([ˈtʃɪk͉ən]) or silent ([ˈtʃɪ(k)ən]).

Sample text

A sample transcription of a written text read aloud, using extIPA and Voice Quality Symbols:^[12]

[ð\ðːə̤ {V̰ ə\ə\ə V̰} ˈhw̥əɹld ˈkʌp ˈf̆\faɪnəlz əv ˈnaɪntin eəti {↓_𝑝ˈtʉ̆ _𝑝↓} ˌɑɹ ˈh\hɛld ɪn sːp\ˈsːp\ʰeᵊn ˈðɪs jəɹ (3 sec) ð͈ːe wɪl ɪnv\ˈv͈ːɔlv ðə tˢˑ\tʴ̥ (.) {_𝑝 tʼ\tʼ _𝑝} ʩ \ {_𝑓 ʩ \ ʩ _𝑓}\ˈt͈ɒ̆p̚ ˈneʃənz əv ðə ˈwəɹld ɪnˑ ə̰ {_𝑝𝑝 tʰˑəʃ\t̆ʰə\təʃ _𝑝𝑝}\ˈt͈ʉɹnəmənt ˈlastɪn ˌoʊvər ˈfɔɹ ˈwiks (..) ˈh͈ɛld ə\ ʔat ˈf\fɔɹtin (...) {_𝑝𝑝 V̰ d\d V̰ _𝑝𝑝} \ ˈdɪfɹənt ˈsɛn{↓təɹʐ↓} ɪn ˈspeᵊn (3 sec) ə̰ (.) ˈɔl əv ðə fˑ\f ˈɔl əv ðə ˈfəɹʂt ˈɹaʉnd ˈɡeᵊmz wɪl bi (..) wɪl bi (.) ɪn ðə (.) w̰̆ə̰ː p\pɹəv\ˈvɪnʃəl {_𝑝 tʼ\tʼ _𝑝} \ {_𝑝𝑝 tʼ\tʼ _𝑝𝑝} (.) tʼ\tʼ (..) {_𝑝𝑝 tʼ\tʼ _𝑝𝑝} ʩ \ ʩ \ {↓ˈtãʉ̃nz↓} wɪð ðə s͢ːsʼ\sʼ\ˈs{↓ɛmi ˈfaɪnəlz↓} and ˈf\faɪnəlz ˈhɛld ɪn (.) ⸨knock on door⸩ bɑɹsə{_𝑝ˈloʊnə and ˈmədɹɪd _𝑝}]

Original text: "The World Cup Finals of 1982 are held in Spain this year. They will involve the top nations of the World in a tournament lasting over four weeks, held at fourteen different centers in Spain. All of the first-round games will be in the provincial towns with the semi-finals, and finals held in Barcelona and Madrid."^[12]

Notes

1. For example, the !Xoon pre-voiced ejective ⟨ˬɡ̥xʼ⟩ in Bennett 2020, p. 102
2. The up-arrow for egressive airflow is no longer present in the 2016 extIPA chart but is mentioned in the accompanying article.
3. Distinct from the mathematical superscript equals sign, U+207C ⟨⁼⟩
4. The symbol for the nareal fricative ⟨n͋⟩ is nearly indistinguishable from the denasal ⟨n͊⟩ at small type sizes. If clarity is needed, a different diacritic such as ⟨n̾⟩ (suggesting nasal escape) might be more distinctive.
5. This diacritic potentially conflicts with the occasional IPA use of a double tilde for a high degree of nasalization, as in Palantla Chinantec /ẽ̃/.^[5] A double (stacked) nasal diacritic may have greater spacing than the single diacritic U+034C, depending on the font. A double nasal diacritic would occur on vowels, while a velopharyngeal diacritic typically occurs on consonants, though not always. For clarity, superscript ⟨◌𐞐⟩ may be used for the velopharyngeal.
6. This diacritic potentially conflicts with the occasional IPA use of a double minus for a highly retracted sound, as in Kwaza [s̠̠].^[6] A double (stacked) minus may be narrower or have greater spacing than the single diacritic U+0347, depending on the font.
7. Normally in the IPA, a transcription with a coronal letter, such as [n], is assumed to be alveolar unless a diacritic is added to indicate otherwise (e.g. dental [n̪] or post-alveolar [n̠]). However, a speech pathologist may need to indicate whether the alveolar target is actually achieved, and so may overtly transcribe an alveolar nasal as [n͇].
8. Occasionally seen on rounded vowel letters to transcribe compressed vowels. This is not an obvious reading of the diacritic and was not the intention of the extIPA.
9. The latter could be specified by doubling the diacritic for extra laminal [s̻̻], [z̻̻].
10. Although not specified by the extIPA, the offset symbols are generally taken to refer to the interlocutor's left and right, not the speaker's.
11. Used in the transcription of Damin.
12. Unicode encodes a combining circle diacritic (U+20DD) that will work with any IPA letter, but as of 2020 it is not widely included in fonts. For example, ⟨ σ⃝ ⟩ combines U+20DD with σ to represent an unidentifiable syllable.
13. Because a formatting trick has been used here, the symbol cannot be copied and pasted from this page. In a supporting font, the combining circle U+20DD will accept the click wildcard letter ⟨Ʞ⟩.
14. The dorsal lateral fricatives will not display unless you have an supporting font installed, such as the free fonts Gentium Plus or Andika.

See also

• Voice Quality Symbols
• Sinological extensions to the International Phonetic Alphabet
• Phonetic symbols in Unicode

References

1. Ball 1993, pp. 39–41
2. Miller, Kirk; Ball, Martin J. (2020). "Unicode request for extIPA support" (PDF). Unicode. L2/20-039.
3. Ball et al. (2018)
4. Duckworth et al. 1990, pp. 277–278
5. Ladefoged 1971, p. 35
6. van der Voort 2005
7. Bernhardt & Ball (1993) Characteristics of Atypical Speech currently not included in the Extensions to the IPA. JIPA 23:1, p. 35–36.
8. Laver 1994
9. Duckworth et al. 1990, p. 279
10. Duckworth et al. 1990, p. 278
11. International Phonetic Association 1999, pp. 176, 192
12. Ball & Lowry 2001, p. 80

Bibliography

• Ball, Martin J. (1993). "Further to Articulatory Force and the IPA Revisions". Journal of the International Phonetic Association. 23 (1): 39–41. doi:10.1017/S0025100300004783. S2CID 143614464.
• Ball, Martin J.; Esling, John H.; Dickson, Craig (December 1995). "The VoQS System for the Transcription of Voice Quality". Journal of the International Phonetic Association. 25 (2): 71–80. doi:10.1017/S0025100300005181. S2CID 145791575.
• Ball, Martin J.; Howard, Sara J.; Miller, Kirk (2018). "Revisions to the extIPA chart". Journal of the International Phonetic Association. 48 (2): 155–164. doi:10.1017/S0025100317000147. S2CID 151863976.
• Ball, Martin J.; Lowry, Orla M. (2001). "Transcribing Disordered Speech". Methods in Clinical Phonetics. London: Whurr. pp. 25–40, 80. doi:10.1002/9780470777879.ch3. ISBN 9781861561848. S2CID 58518097.
• Bennett, William G. (2020). "Click Phonology". In Sands, Bonny (ed.). Click Consonants. Empirical Approaches to Linguistic Theory. Vol. 15. Brill. pp. 74–128. doi:10.1163/9789004424357_003. ISBN 978-90-04-23268-6. S2CID 243697259.
• Duckworth, Martin; Allen, George; Hardcastle, William; Ball, Martin J. (1990). "Extensions to the International Phonetic Alphabet for the transcription of atypical speech". Clinical Linguistics and Phonetics. 4 (4). International Clinical Phonetics and Linguistics Association: 273–280. doi:10.3109/02699209008985489.
• Hesselwood, Barry; Howard, Sara (2008). "Clinical Phonetic Transcription". In Ball, Martin J.; Perkins, Michael R.; Müller, Nicole; Howard, Sara (eds.). The handbook of Clinical Linguistics. Malden, MA: Blackwell. doi:10.1002/9781444301007.ch23. ISBN 9781405135221.
• International Phonetic Association (1999). Handbook of the International Phonetic Association : a guide to the use of the International Phonetic Alphabet. Cambridge, UK: Cambridge University Press. ISBN 9780521637510.
• Ladefoged, Peter (1971). Preliminaries to linguistic phonetics. Chicago, IL: University of Chicago Press. ISBN 0-226-46787-2. LCCN 75-179318.
• Laver, John (1994). Principles of phonetics. Cambridge Textbooks in Linguistics. Cambridge, UK: Cambridge University Press. doi:10.1017/CBO9781139166621. ISBN 9781139166621.
• van der Voort, Hein (2005). "Kwaza in a Comparative Perspective". International Journal of American Linguistics. 71 (4). University of Chicago Press: 365–412. doi:10.1086/501245. S2CID 224808983.

External links

• Chart of extended IPA symbols for disordered speech (PDF, revised to 2015)
• Pronunciation videos of consonants in the main extIPA chart as of 2008