In phonetics, a back vowel is a [[vowel sound]] that is produced by raising the back of the tongue towards the soft palate at the back of the mouth. Back vowels are characterized by a low frequency of the first formant (F1) and a high frequency of the second formant (F2). Examples of back vowels in English include /ɑ/ (as in "father"), /ɔ/ (as in "thought"), and /u/ (as in "boot"). Back vowels are important in distinguishing between different vowel sounds in many languages.