Uvulars are consonants articulated with the back of the tongue against or near the uvula, that is, further back in the mouth than velar consonants. Uvulars may be stops, fricatives, nasals, trills, or approximants, though the IPA does not provide a separate symbol for the approximant, and the symbol for the voiced fricative is used instead. Uvular affricates can certainly be made but are rare: they occur in some southern High-German dialects, as well as in a few African and Native American languages. Uvular consonants are typically incompatible with advanced tongue root, and they often cause retraction of neighboring vowels.