There are 10 monophthongal and 3 diphthongal vowel phonemes in Czech: /iː ɪ ɛː ɛ aː a oː o uː u eu̯ au̯ ou̯/. Czech is a quantity language: it differentiates five vowel qualities that occur as both phonologically short and long. The short and long counterparts generally do not differ in their quality, although long vowels may be more peripheral than short vowels.
As for the high front vowel pair /iː/-/i/, there are dialectal differences with respect to phonetic realisation of the contrast: in the Bohemian variety of Czech, the two vowels are differentiated by both quality and duration, while in the Eastern Moravian variety of Czech the primary difference is that of duration. Therefore, in the Bohemian variety, the transcription [iˑ]-[ɪ] more accurately reflects the trade off between the qualitative and the durational difference in these vowels, while in the Eastern Moravian variety of Czech, the transcription [iː]-[i] captures the primary durational difference. 
Besides length, Czech differentiates three degrees of height and three degrees of backness. 
Vowel modifications such as nasalization do not occur in Czech. The vowels are never reduced and undergo no assimilations. Vowel length and quality is independent of the stress.
Short vowels 
- /ɪ/ is spelled as i and y
- /ɛ/ is spelled as e and ě
- /a/ is spelled as a
- /o/ is spelled as o
- /u/ is spelled as u
Long vowels 
- /iː/ is spelled í and ý
- /ɛː/ is spelled as é
- /aː/ is spelled as á
- /oː/ is spelled as ó (this phoneme occurs almost exclusively in words of foreign origin)
- /uː/ is spelled as ú and ů
- /au̯/ is spelled as au (occurs almost exclusively in words of foreign origin)
- /eu̯/ is spelled as eu (occurs in words of foreign origin only)
- /ou̯/ is spelled as ou
The phonemes /o/ and /oː/ are sometimes referred to as /ɔ/ and /ɔː/. This transcription describes the pronunciation in Central Bohemia and Prague, which is more open. The standard pronunciation is something between [o(ː)] and [ɔ(ː)], i.e. mid back vowel.
Note that ě is not a separate vowel. It simply denotes [ɛ] after a palatal stop or nasal (e.g. něco [ɲɛtso]) and [jɛ] after other consonants (e.g. bě [bjɛ]).
Vowel groups ia, ie, ii, io, and iu in foreign words are not regarded as diphthongs, they are pronounced with /j/ between the vowels [ɪja, ɪjɛ, ɪjɪ, ɪjo, ɪju].
The following chart shows a complete list of the consonant phonemes of Czech:
|Stop||p b||t d||c ɟ||k (ɡ)|
|Affricate||t͡s (d͡z)||t͡ʃ (d͡ʒ)|
|Fricative||(f) v||s z||ʃ ʒ||x||ɦ|
The phoneme /r̝/, written ⟨ř⟩, is a raised alveolar non-sonorant trill. (Listen: Antonín Dvořák [ˈantoɲiːn ˈdvor̝aːk] (help·info)) Its rarity makes it difficult to produce for foreign learners of Czech, who may pronounce it as /rʒ/; however, it contrasts with /rʒ/ in words like ržát /rʒaːt/, which is pronounced differently from řád /r̝aːt/. The basic realization of this phoneme is voiced, but it is voiceless [r̝̊] when preceded or followed by a voiceless consonant or at the end of a word.
/t/ and /d/ can be pronounced as dental stops.
The voiceless realization of the phoneme /ɦ/ is velar [x].
Secondary articulations (aspiration, labialization, velarization, palatalization, etc.) are not used in Czech.
Glottal stop 
The glottal stop is not a separate phoneme. Its use is optional and it may appear as the onset of an otherwise vowel-initial syllable. The pronunciation with or without the glottal stop does not affect the meaning and is not distinctive.
The glottal stop has two functions in Czech:
- The emphasis on the boundaries between words or in composite words is usually inserted between two vowels which do not form a diphthong, e.g. používat [poʔuʒiːvat] (to use), táta a máma [taːta ʔa maːma] (dad and mum); in words beginning with a vowel, it separates prepositions from words beginning with a vowel, e.g. z okna [s ʔokna] (out of the window); it is also inserted before initial vowels of the second part of composite words, e.g. trojúhelník [trojʔuːɦɛlɲiːk] (triangle). This usage of the glottal stop is usual in Bohemia. Pronunciation without it is typical of Moravian regions, e.g. [trojuːɦɛlɲiːk], [zokna]. Both variants are regarded as correct.
- Certain words can be emphasized by the use of the glottal stop.
In the standard pronunciation, the glottal stop is never inserted between two vowels in words of foreign origin, e.g. in the word koala.
Marginal consonant phonemes 
The phonemes /f/, /ɡ/, and the affricates /d͡z/ and /d͡ʒ/ occur in words of foreign origin or dialects only. (However, [f] and [g] may also occur as a result of voicing assimilation of /v/ and /k/ respectively, see "assimilation of voice" below.) Phonetically, the affricates can occur at morpheme boundaries (see consonant merging below). [f] also appears in the verb doufat and its derivatives (as a result of contraction of Proto-Slavic *upvati), and in some words of onomatopoeic origin (foukat).
Consonants in the script 
Other consonants are represented by the same characters (letters) as in the IPA.
Consonant assimilation 
Realizations of consonant phonemes are influenced by their surroundings. The position of phonemes in words can modify their acoustic realizations without a change of the meaning.
Assimilation of the place of articulation 
- Labiodental [ɱ] is a realization of /m/ before labiodental fricatives /f/ and /v/, e.g. in the word tramvaj [traɱvaj] (tramway).
- Velar [ŋ] is a realization of /n/ before velar stops /k/ and /ɡ/, e.g. in the word banka [baŋka] (bank).
The former assimilation is optional. Realization as [tramvaj] is possible, especially in more prestigious registers.
Assimilation of voice 
Assimilation of voice is an important feature of Czech pronunciation. Voiced obstruents are, in certain circumstances, realized voiceless and vice versa. It is not represented orthographically where more etymological principles are applied. Assimilation of voice applies in these circumstances:
- In consonant groups – all obstruents in the group are realized either voiced or voiceless. It is mostly given by the last consonant in the group (regressive assimilation), e.g. roztok [rostok] ('solution').
- Voiced obstruents are realized voiceless in the final position in words (final devoicing). Compare led (ice) – ledu [lɛdu] (genitive form) vs. let (flight) – letu [lɛtu] (genitive form) – the nominative forms of the both words (led – let) have the same realization [lɛt] due to the final devoicing. But in the other inflection forms their pronunciation differs.
Voiced and voiceless obstruents form pairs in which the assimilation of voice applies (see table):
Sonorants (/m/, /n/, /ɲ/, /j/, /r/ and /l/) have no voiceless counterparts and are never devoiced. They do not cause the voicing of voiceless consonants in standard pronunciation, e.g. sledovat [slɛdovat] (to watch).
There are some exceptions to the rules described above:
- The phoneme /v/ also does not cause the voicing of preceding voiceless consonants (that is, it acts as a sonorant before vowels), e.g. světlo [svjɛtlo] (light). However, /v/ followed by a voiceless consonant is also realized voiceless, e.g. vsadit [fsaɟɪt] (to bet).
- The phonemes /x/ (written <ch>), and /ɦ/ (written <h>) form a special voice pair even though the places of articulation differ, e.g. vrh [vrx] (a throw) – vrhu [vrɦu] (genitive form). The phoneme /x/ followed by a voiced obstruent can by realized as either [ɦ] or [ɣ], e.g. abych byl [abɪɣ.bɪl] (so that I would ... (conditional)). The phoneme /ɦ/ undergoes progressive assimilation after /s/ in Bohemian pronunciation, e.g. na shledanou [na sxlɛdanou̯] (good-bye), meanwhile standard regressive assimilations are typical of Moravian pronunciation, [na zɦlɛdanou̯].
- The phoneme /r̝/ does not cause assimilations of adjacent consonants, but it undergoes progressive as well as regressive assimilation according to its surroundings, e.g. při [pr̝̊ɪ] (by, during). Its basic realization is voiced. In final positions, it is voiceless.
Consonant merging 
Two identical consonant phonemes (or allophones) can meet in morpheme boundaries during word formation. In many cases, especially in suffixes, two identical consonant sounds merge in one sound in the pronunciation, e.g. cenný [t͡sɛniː] (valuable), měkký [mɲɛkiː] (soft).
In prefixes and composite words, lengthened or doubled pronunciation (gemination) is obvious. It is necessary in cases of different words: nejjasnější [nɛjjasɲɛjʃiː] (the clearest, the brightest) vs. nejasnější [nɛjasɲɛjʃiː] (more unclear). Doubled pronunciation is perceived as hypercorrect in cases like [t͡sɛnniː] or [mɲɛkkiː].
Combinations of stops (/d/, /t/, /ɟ/, /c/) and fricatives (/s/, /z/, /ʃ/, /ʒ/) usually produce affricates ([t͡s, d͡z, t͡ʃ, d͡ʒ]): dětský [ɟɛt͡skiː] (children’s). Both phonemes are pronounced separately in careful pronunciation: [ɟɛt.skiː].
Consonant merging is perceived as careless[clarification needed] at word boundaries, e.g. pojď sem (come here) realized as [pot͡sɛm]. It is necessary to pronounce all phonemes clearly and separately: [pojc.sɛm].
The stress is always fixed to the first syllable of a word. The exceptions are following:
- One-syllabic prepositions usually form a unit with following words. Therefore, the stress moves to the prepositions, ˈPraha (Prague) → ˈdo Prahy (to Prague). This rule is not usually applied in words which have four or more syllables: e.g., na ˈkoloˌnádě (on the colonnade).
- Some one-syllabic words (e.g. mi (me), ti (you), to (it), se, si (oneself), jsem (am), jsi (are), etc.) are clitics—they are not stressed and form a unit with preceding words, therefore they cannot be the first words in sentences. Example: ˈNapsal jsem ti ten ˈdopis (I have written the letter to you). (See Czech word order for details.)
Long words can have the secondary stress which is usually placed on every odd syllable, e.g. ˈnej.krás.ˌněj.ší (the most beautiful).
The stress has no lexical or phonological function; it denotes boundaries between words but does not distinguish word meanings. It has also no influence on the quality or quantity of vowels, i.e. the vowels are not reduced in unstressed syllables and can be both short and long regardless of the stress. Thus, the Czech rhythm can be considered as isosyllabic.
Czech is not a tonal language. Tones or melodies are not lexical distinctive features. However, intonation is a distinctive feature on the level of sentences. Tone can differentiate questions from simple messages, as it need not necessarily be indicated by the word order:
- On to udělal. (He did it.)
- On to udělal? (Did he do it?)
- On to udělal?! (He did it?!)
All these sentences have the same lexical and grammatical structure. The differences are in their intonation.
Open syllables of type CV are the most abundant in Czech texts. It is supposed that all syllables were open in the Proto-Slavic language. Syllables without consonant onset occur with a relatively little frequency. Using the glottal stop as a preture in such syllables confirms this tendency in the pronunciation of Bohemian speakers. In Common Czech, the most widespread Czech intedialect, prothetic v– is added to all words beginning with o– in standard Czech, e.g. voko instead of oko (eye).
The general structure of Czech syllables is:
- C – consonant
- V – vowel or syllabic consonant
Thus, Czech word can have up to four consonants in the initial group and three consonants in the final group (not including syllabic consonants). The syllabic nucleus is usually formed by vowels or diphthongs, but in some cases syllabic sonorants (/r/ and /l/, rarely also /m/ and /n/) can be found in the nucleus, e.g. vlk [vl̩k] (wolf), krk [kr̩k] (neck), osm [osm̩] (eight).
Vowel groups can occur in the morpheme boundaries. They cannot include more than two vowels. Both vowels in the groups are separate syllabic nuclei and do not form diphthongs.
Phoneme alternations in morphophonemes (changes which do not affect morpheme meaning) are frequently applied in inflections and derivations. They are divided into vowel and consonant alternations. Both types can be combined in a single morpheme:
- kniha /kɲɪɦa/ [kɲɪɦa] (book)
- v knize /vkɲɪzɛ/ [fkɲɪzɛ] (in a book)
- knížka /kɲiːʒka/ [kɲiːʃka] (little book)
Vowel alternations 
The most important alternations are those of short and long phonemes. Some of these alternations are correlative, i.e. the phonemes in pairs differ in their length only. Due to historical changes in some phonemes (/oː/ → /uː/, /uː/ → /ou̯/), some alternations are disjunctive, i.e. the phonemes in pairs are different in more features. These alternations occur in word roots during inflections and derivations, and they also affect prefixes in derivations.
|Short phoneme||Long phoneme||Examples, notes|
|/a/||/aː/||zakladatel (founder) – zakládat (to found)|
|/ɛ/||/ɛː/||letadlo (airplane) – létat (to fly)|
|/ɪ/||/iː/||litovat (be sorry) – lítost (regret)
vykonat (to perform) – výkon (performance)
|/o/||/uː/||koně (horses) – kůň (horse)|
|/u/||/uː/||učesat (to comb) – účes (hair style)
(in initial positions in morphemes only)
|/u/||/ou̯/||kup! (buy!) – koupit (to buy)
(in other positions)
Some other disjunctive vowel alternations occur in word roots during derivations (rarely also during inflections):
- |a/ɛ|: šťastný (happy) – štěstí (happiness); vejce (egg) – vajec (gen. pl.)
- |ɛ/o|: veze (is carrying) – vozí (carries)
- |aː/iː|: hřát (to warm) – zahřívat (to warm up)
- |aː/ɛ|: otřást (to shake) – otřes (tremor)
- |aː/o|: vyrábět (to produce) – výroba (production)
- |ɛ/iː|: zaječice (doe) – zajíc (hare)
Emergence/disappearance alternations also take place, i.e. vowels alternate with null phonemes. In some allomorphs, /ɛ/ is inserted between consonants in order to make the pronunciation easier:
- |ɛ/∅|: matka (mother) – matek (gen. pl.); lež (lie) – lži (lies)
It also occurs in some prepositions which have vocalised positional variants: v domě – (in a house) – ve vodě (in water); s tebou (with you) – se mnou (with me), etc.
Some other alternations of this type occur, but they are not so frequent:
- |ɪ/∅|: vypsat (to write out, to extract) – výpis (abstract, extract)
- |ɪː/∅|: vytknout (to reproach once) – vytýkat (to reproach); ubrat (to take away once) – ubírat (to take away)(examples of verb pairs with perfective and imperfective aspects)
- |u/∅|: suchý (dry) – schnout (to become dry)
Consonant alternation 
Alternations of hard and soft consonants represent the most abundant type. They occur regularly in word-stem final consonants before certain suffixes (in derivations) and endings (in inflections). Hard consonants are softened if followed by soft /ɛ/ (written <e/ě>), /ɪ/, or /iː/ (written <i> and <í>, not <y> and <ý>). These changes also occur before some other suffixes (e.g. –ka). Softening can be both correlative and disjunctive.
|/d/||/ɟ/||mladý (young – masc. sg.) – mladí (young masc. anim. pl.)|
|/t/||/c/||plat (pay, wages) – platit (to pay)|
|/n/||/ɲ/||žena (woman) – ženě (woman – dat.)|
|/r/||/r̝̊/||dobrý (good – adj.) – dobře (good – adv., well)|
|/s/||/ʃ/||učesat (to comb) – učešu (I will comb)|
|/z/||/ʒ/||ukázat (to show) – ukážu (I will show)|
|/t͡s/||/t͡ʃ/||ovce (sheep) – ovčák (shepherd)|
|/ɡ/||/ʒ/||Riga – rižský (adj.)|
|/z/||v Rize (in Riga)|
|/ɦ/||/ʒ/||Praha (Prague) – Pražan (Prague citizen)|
|/z/||v Praze (in Prague)|
|/x/||/ʃ/||prach (dust) – prášit (to raise dust)|
|/s/||smíchat (to mix) – směs (mixture)|
|/k/||/t͡ʃ/||vlk (wolf) – vlček (little wolf)|
|/sk/||/ʃc/||britský (British – masc. sg.) – britští (British – masc. anim. pl.)|
|/t͡sk/||/t͡ʃc/||anglický (English – adj.) – angličtina (English – language)|
|/b/||/bj/||nádoba (vessel) – v nádobě (in a vessel)
bílý (white) – bělásek (cabbage white butterfly)
|/p/||/pj/||zpívat (to sing) – zpěvák (singer)
|/v/||/vj/||tráva (grass) – na trávě (on the grass)
vím (I know) – vědět (to know)
|/f/||/fj/||harfa (harp) – na harfě (on the harp)|
|/m/||/mɲ/||dům (house) – v domě (in a house)
smích (laughter) – směšný (laughable)
The last four examples are emergence alternations. A phoneme (/j/ or /ɲ/) is inserted in the pronunciation, but for the historical reasons, these changes are indicated by <ě> in the orthography (see the orthographic notes below). These alternations are analogical with softening alternations, therefore they are mentioned here. They also occur in word roots together with vowel alternations (usually |ɛ/iː|).
Some other alternations occur but they are not so frequent. They are often little evident:
- |p/∅|: topit se – tonout (to be drowning – both words)
- |b/∅|: zahýbat (to be turning) – zahnout (to take a turn)
- |p/∅|: vléct (to lug) – obléct (to dress)
Orthographic notes 
|This section requires expansion. (May 2013)|
|dy [dɪ]||ty [tɪ]||ny [nɪ]|
|di [ɟɪ]||ti [cɪ]||ni [ɲɪ]|
|dí [ɟiː]||tí [ciː]||ní [ɲiː]|
|dě [ɟɛ]||tě [cɛ]||ně [ɲɛ]|
See also 
|Wikimedia Commons has media related to: Czech pronunciation|
- Czech alphabet
- Czech declension
- Czech language
- Czech orthography
- Czech verb
- History of the Czech language
- Kučera, H. (1961). The Phonology of Czech. s’ Gravenhage: Mouton & Co.
- Šimáčková, Š., Podlipský, V. J., & Chládková, K. (2012). Czech spoken in Bohemia and Moravia. Journal of the International Phonetic Association, 42 (2), 225–232. DOI: 10.1017/S0025100312000102
- Kučera, H. (1961). The Phonology of Czech. s’ Gravenhage: Mouton & Co.
- Dankovičová, J. (1999). Czech. In Handbook of the International Phonetic Association. Cambridge University Press. pages=70–74.
- Šiška Z. Fonetika a fonologie. Univerzita Palackého v Olomouci, 2. vyd., Olomouc 2005. ISBN 80-244-1044-3.
- Duběda T. Jazyky a jejich zvuky. Univerzálie a typologie ve fonetice a fonologii. Karolinum, Praha 2005. ISBN 80-246-1073-6.
- Karlík P., Nekula M., Pleskalová J. (eds.). Encyklopedický slovník češtiny. Nakl. Lidové noviny. Praha 2002. ISBN 80-7106-484-X.
- Karlík P., Nekula M., Rusínová Z. (eds.) Příruční mluvnice češtiny. Nakladatelství Lidové noviny, Praha 1995. ISBN 80-7106-134-4.
- Čermák F. Jazyk a jazykověda. Karolinum, Praha 2004. ISBN 80-246-0154-0.