Standard Czech contains ten basic vowel phonemes, and three more found only in loanwords. They are /a/, /ɛ/, /ɪ/, /o/, and /u/, their long counterparts /aː/, /ɛː/, /iː/, /oː/ and /uː/, and three diphthongs, /ou̯/, /au̯/ and /ɛu̯/. The latter two diphthongs and the long /oː/ are exclusive to loanwords. Vowels are never reduced to schwa sounds when unstressed. Each word usually has primary stress on its first syllable, except for enclitics (minor, monosyllabic, unstressed syllables). In all words of more than two syllables, every odd-numbered syllable receives secondary stress. Stress is unrelated to vowel length, and the possibility of stressed short vowels and unstressed long vowels can be confusing to students whose native language combines the features (such as English).
Voiced consonants with unvoiced counterparts are unvoiced at the end of a word before a pause, and in consonant clusters voicing assimilation occurs, which matches voicing to the following consonant. The unvoiced counterpart of /ɦ/ is /x/.
Czech consonants are categorized as “hard”, “neutral” or “soft”:
- Hard: /d/, /ɡ/, /ɦ/, /k/, /n/, /r/, /t/, /x/
- Neutral: /b/, /f/, /l/, /m/, /p/, /s/, /v/, /z/
- Soft: /c/, /ɟ/, /j/, /ɲ/, /r̝/, /ʃ/, /ts/, /tʃ/, /ʒ/
This distinction describes the declension patterns of nouns, which is based on the category of a noun’s ending consonant. Hard consonants may not be followed by i or í in writing, or soft ones by y or ý (except in loanwords such as kilogram). Neutral consonants may take either character. Hard consonants are sometimes known as “strong”, and soft ones as “weak”.
The phoneme represented by the letter ř (capital Ř) is considered unique to Czech. It represents the raised alveolar non-sonorant trill (IPA: [r̝]), a sound somewhere between Czech’s r and ž (example: “řeka” (river) (help·info)), and is present in Dvořák. In unvoiced environments, /r̝/ is realized as its voiceless allophone [r̝̊].
The consonants /r/ and /l/ can be syllabic, acting as syllable nuclei in place of a vowel. Strč prst skrz krk (“Stick [your] finger through [your] throat”) is a well-known Czech tongue twister using only syllabic consonants.