Consonants Manner of articulation The symbols below are defined for indeterminate sounds by the
Extensions to the International Phonetic Alphabet (extIPA), which recommends the use of a surrounding circle . Note that these are all
manners of articulation. may also be used for any
voiced sibilant. may be used for any
implosive.
Place of articulation Several symbols are commonly used for indeterminate
places of articulation. may also be used for any
voiceless alveolar, in which case is used for any voiced alveolar. One may prefer to use iconographic
hooks on for certain places.
Proto-Indo-European studies Those reconstructing
Proto-Indo-European phonology use the following cover symbols, some of which differ from the examples above.
Vowels Capitalized vowels are commonly used in discussions of languages with
vowel harmony. They often indicate different harmonic variants of an underlying
archiphonemic vowel.
Syllables In phonotactics, cover symbols for syllable structures are often written with
Greek letters.
Other symbols